Effect of isoenergetic intake of three or nine meals on plasma lipoproteins and glucose metabolism

Chronomedicine Insights: Evaluating the Impact of Time-Restricted Meal Intake on Lipid Profile Parameters Among Individuals With Type 2 Diabetes in Northern India

INTRODUCTION

Time-restricted meal intake (TRM) has shown potential benefits such as enhanced insulin sensitivity, lowered blood sugar levels, and possible weight loss in individuals with type 2 diabetes mellitus (T2DM). Our study aimed to investigate the impact of TRM on lipid profile parameters such as total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL) in fasting conditions in T2DM patients.

METHODS

In total, 400 patients from the endocrinology department at King George's Medical University (KGMU), Lucknow were enrolled in this study, adhering to the guidelines of the American Diabetes Association (ADA). Male and female patients with recently diagnosed T2DM (in the past five years), aged between 25 to 60 years, on oral anti-diabetic therapy excluding insulin, expressing willingness to provide written consent and to adhere to TRM were included in the TRM group. It was a longitudinal study as diabetic dyslipidemia is primarily caused by insulin resistance and nutritional reasons and we wanted to assess the effect of TRM on lipid profile in T2DM patients. Patients were enrolled via simple random sampling using the random number table method (computerized). The TRM group had an early dinner at 7 pm whereas the control group was of non-TRM/late-night eaters. TRM group was given comprehensive guidance including strategies to manage hunger, permissible beverage options (water and prescribed medication) during the fasting period, and daily maintenance of a diary documenting their timing, type, and quantity of food intake which they were requested to bring fortnightly. Emphasis was placed on recording even minor dietary items consumed throughout the day. The TRM group consumed food ad libitum during a 12-hour eating window from breakfast at 7 am to dinner at 7 pm. Data distribution was non-parametric. Mann-Whitney U test compared TRM and control group using mean values at baseline and follow-ups. Analysis used GraphPad Prism 9.2.0 software (GraphPad Inc., La Jolla, CA). A p-value less than 0.05 (p < 0.05) was considered statistically significant.

RESULTS

A total of 127 patients were lost to follow-up, resulting in 273 patients who completed the study. The mean value of TC in the TRM and non-TRM groups using the Mann-Whitney U test registered a highly significant p-value <0.0001 at 18 months, with a decrease of 14.17% from baseline in the TRM group and a decrease of 1.53% from baseline in the non-TRM group. The TRM group had a decrease of 24.75% in TG from a baseline value of 145.4±41.9, whereas the non-TRM group showed a decrease of 2.2% from a baseline value of 154.7±37.30 (p-value <0.0001). The TRM group showed an increase of 9.25% in HDL from a baseline value of 50.14±8.58; the non-TRM group showed an increase of 0.82% from a baseline value of 48.62±9.31 (p-value <0.0001). TRM group showed a decrease of 8.62% in LDL from a baseline value of 68.20±16.2 while the non-TRM group showed an increase of 1.54% from a baseline value of 65.38±19.3 (p-value <0.0002). The TRM group showed a decrease of 13.97% in VLDL from a baseline value of 32.20±18.7; the non-TRM group showed an increase of 4% from a baseline value of 30.16±24.2 (p-value <0.0001).

CONCLUSION

Our study's promising results underscore the potential of TRM as an effective strategy for managing dyslipidemia in individuals with T2DM, even over prolonged periods.

The effects of eating frequency on changes in body composition and cardiometabolic health in adults: a systematic review with meta-analysis of randomized trials

BACKGROUND

Eating frequency may affect body weight and cardiometabolic health. Intervention trials and observational studies have both indicated that high- and low-frequency eating can be associated with better health outcomes. There are currently no guidelines to inform how to advise healthy adults about how frequently to consume food or beverages.

AIM

To establish whether restricted- (≤ three meals per day) frequency had a superior effect on markers of cardiometabolic health (primary outcome: weight change) compared to unrestricted-eating (≥ four meals per day) frequency in adults.

METHODS

We searched Medline (Ovid), Embase, CINAHL (EBSCO), Cochrane Central Register of Controlled Trials (CENTRAL), CAB Direct and Web of Science Core Collection electronic databases from inception to 7 June 2022 for clinical trials (randomised parallel or cross-over trials) reporting on the effect of high or low-frequency eating on cardiometabolic health (primary outcome: weight change). Trial interventions had to last for at least two weeks, and had to have been conducted in human adults. Bias was assessed using the Cochrane Risk of Bias tool 2.0. Standardized mean differences (SMD) and 95% confidence intervals were calculated for all outcomes. Certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

Seventeen reports covering 16 trials were included in the systematic review. Data from five trials were excluded from meta-analysis due to insufficient reporting. 15 of 16 trials were at high risk of bias. There was very low certainty evidence of no difference between high- and low-frequency eating for weight-change (MD: -0.62 kg, CI95: -2.76 to 1.52 kg, p = 0.57).

CONCLUSIONS

There was no discernible advantage to eating in a high- or low-frequency dietary pattern for cardiometabolic health. We cannot advocate for either restricted- or unrestricted eating frequency to change markers of cardiometabolic health in healthy young to middle-aged adults.

PROTOCOL REGISTRATION

CRD42019137938.

Understanding the link between frequency of eating and cardiometabolic health outcomes in Americans who "snack"

On average, Americans ages 2 yr and older eat 5 or more times per day and consume nearly a quarter of their daily energy outside of breakfast, lunch, and dinner. Frequency of eating (FOE) has been identified by both the 2020 Dietary Guidelines for Americans Scientific Advisory Committee and the American Heart Association as an important area of study to improve the dietary patterns and overall health of the American public. However, the current evidence on FOE is conflicting; it does not indicate whether eating more frequently is a healthful behavior or not. Clinical and prospective studies have shown that FOE has an inverse relationship with some cardiometabolic health markers, including total cholesterol and low-density lipoprotein cholesterol concentrations, but the relationship between FOE and other health markers such as high-density lipoprotein cholesterol concentrations, blood pressure, obesity, and coronary heart disease incidence remains unclear. Several factors may affect the relationship between FOE and cardiometabolic health including the types of foods consumed, time of day, motivation to eat, cultural background, age, sex, and food security status. Another factor affecting both the relationship between FOE and health as well as the research on FOE and health is how eating occasions are labeled. Many definitions have been proposed and used in research to delineate between meals and snacks, but a consistent definition is not currently used for "snacks," even in official dietary guidance. With the current limitations in the body of research, conclusions about the healthfulness of frequent eating cannot be drawn. In addition, conclusions cannot be drawn on the healthfulness of eating snacks (as an eating occasion) or more than 3 meals per day. More directed research is required to understand the relationships between the labels used for an eating occasion and cardiometabolic health outcomes as well as the health impacts of frequent food and beverage consumption and how and why they may vary among different population groups.

Effects of Diet, Lifestyle, Chrononutrition and Alternative Dietary Interventions on Postprandial Glycemia and Insulin Resistance

As years progress, we are found more often in a postprandial than a postabsorptive state. Chrononutrition is an integral part of metabolism, pancreatic function, and hormone secretion. Eating most calories and carbohydrates at lunch time and early afternoon, avoiding late evening dinner, and keeping consistent number of daily meals and relative times of eating occasions seem to play a pivotal role for postprandial glycemia and insulin sensitivity. Sequence of meals and nutrients also play a significant role, as foods of low density such as vegetables, salads, or soups consumed first, followed by protein and then by starchy foods lead to ameliorated glycemic and insulin responses. There are several dietary schemes available, such as intermittent fasting regimes, which may improve glycemic and insulin responses. Weight loss is important for the treatment of insulin resistance, and it can be achieved by many approaches, such as low-fat, low-carbohydrate, Mediterranean-style diets, etc. Lifestyle interventions with small weight loss (7-10%), 150 min of weekly moderate intensity exercise and behavioral therapy approach can be highly effective in preventing and treating type 2 diabetes. Similarly, decreasing carbohydrates in meals also improves significantly glycemic and insulin responses, but the extent of this reduction should be individualized, patient-centered, and monitored. Alternative foods or ingredients, such as vinegar, yogurt, whey protein, peanuts and tree nuts should also be considered in ameliorating postprandial hyperglycemia and insulin resistance. This review aims to describe the available evidence about the effects of diet, chrononutrition, alternative dietary interventions and exercise on postprandial glycemia and insulin resistance.

Meal Timing and Glycemic Control during Pregnancy-Is There a Link?

Hyperglycemia during pregnancy and gestational diabetes mellitus (GDM) constitute an important public health problem due to their prevalence and long-term health consequences both for the mother and offspring. Results from studies in rodents and some clinical investigations suggest that meal time manipulation may be a potential lifestyle approach against conditions involving perturbations in glucose homeostasis (e.g., hyperglycemia, insulin resistance, diabetes, etc.). The purpose of this review is to summarize and critically evaluate the current literature on the role of meal timing and daily nutrient distribution on glycemic control during pregnancy. Only a small number of mostly observational studies have assessed the role of meal timing in glucose homeostasis during pregnancy. Food consumption earlier in the day and short-term fasting with adequate nutrient intake may improve glycemic control during the second and third trimester of gestation. Considering that the field of chrononutrition is still in its infancy and many questions remain unanswered, future prospective and carefully designed studies are needed to better understand the role of meal timing in metabolic homeostasis and maternal and fetal health outcomes during pregnancy.

Snacking patterns throughout the life span: potential implications on health

Eating outside the three main meals - in other words, snacking - is a part of the dietary pattern of individuals in all stages of life. The quality and pattern of snacking have an impact on health during the life span. Thus, the aim of this review was to evaluate various patterns and health outcomes of the snacking habits of different demographical groups, from children to the elderly, throughout their life span. We discuss the snacking pattern among children and adolescents, which is characterized by consuming high energy foods with low nutrient value, and which is associated with increased risk of obesity. During university years, study stress and lack of time were obstacles to a healthy dietary pattern involving nutritious snacks, although awareness of the importance of healthy snacks was higher in this group than among younger age groups. Employment status and skipping regular meals were important factors affecting snacking quality and patterns in adulthood. Unhealthy snacks, high in energy, sugar, and salt and low in nutrients, were demonstrated to have a negative impact on individuals' health, such as oral health, blood pressure, obesity, and diabetes. In conclusion, encouraging individuals to consume healthy snacks that are high in nutrients through education to help them plan for their snacks is important to enhance health and reduce disease risk.

The effect of meal frequency on biochemical cardiometabolic factors: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although several randomized controlled trials (RCTs) have supported the beneficial effects of higher meal frequency (MF) on cardiometabolic risk factors, the putative effects of higher MF on health remain inconclusive. This study systematically reviewed the evidence from RCTs of the effect of higher compared with lower MF on the blood lipid profile, glucose homeostasis, and adipokines.

METHODS

PubMed, Scopus, ISI Web of Science, and the Cochrane database were searched up to October 2020 to retrieve relevant RCTs. A DerSimonian and Laird random effects model was used to pool mean differences and 95% CI for each outcome. The quality of studies and evidence was assessed through standard methods.

RESULTS

Twenty-one RCTs (686 participants) were included in this meta-analysis. Overall results showed a significant improvement in total cholesterol [weighted mean difference (WMD) = -6.08 mg/dl; 95% CI: -10.68, -1.48; P = 0.01; I² = 88%], and low-density cholesterol (LDL-C) (WMD = -6.82 mg/dl; 95% CI: -10.97, -1.60; P = 0.009; I² = 85.7%), while LDL-C to high-density cholesterol ratio (LDL-C: HDL-C) increased (WMD = 0.22; 95% CI: 0.07, 0.36; P = 0.003; I² = 0.0%) in higher MF vs. lower MF. No significant effects were found on measures of glycemic control, apolipoproteins-A1 and B, or leptin. In subgroup analyses, higher MF significantly reduced serum triglyceride (TG), and increased HDL-C, compared with lower MF in interventions > 12 weeks, and decreased serum TC and LDL-C in healthy participants. A significant reduction in LDL-C also was observed in studies where the same foods given both arms, simply divided into different feeding occasions, and in feeding studies, following higher MF compared to lower MF.

CONCLUSION

Our meta-analysis found that higher, compared with lower MF may improve total cholesterol, and LDL-C. The intervention does not affect measures of glycemic control, apolipoproteins-A1 and B, or leptin. However, the GRADE ratings of low credibility of the currently available evidence highlights the need for more high-quality studies in order to reach a firm conclusion.

Impact of Meal Frequency on Anthropometric Outcomes: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials

The relation between meal frequency and measures of obesity is inconclusive. Therefore, this systematic review and network meta-analysis (NMA) set out to compare the isocaloric effects of different meal frequencies on anthropometric outcomes and energy intake (EI). A systematic literature search was conducted in 3 electronic databases (Medline, Cochrane Library, Web of Science; search date, 11 March 2019). Randomized controlled trials (RCTs) were included with ≥2 wk intervention duration comparing any 2 of the eligible isocaloric meal frequencies (i.e., 1 to ≥8 meals/d). Random-effects NMA was performed for 4 outcomes [body weight (BW), waist circumference (WC), fat mass (FM), and EI], and surface under the cumulative ranking curve (SUCRA) was estimated using a frequentist approach (P-score: value is between 0 and 1). Twenty-two RCTs with 647 participants were included. Our results suggest that 2 meals/d probably slightly reduces BW compared with 3 meals/d [mean difference (MD): -1.02 kg; 95% CI: -1.70, -0.35 kg) or 6 meals/d (MD: -1.29 kg; 95% CI: -1.74, -0.84 kg; moderate certainty of evidence). We are uncertain whether 1 or 2 meals/d reduces BW compared with ≥8 meals/d (MD1 meal/d vs. ≥8 meals/d: -2.25 kg; 95% CI: -5.13, 0.63 kg; MD2 meals/d vs. ≥8 meals/d: -1.32 kg; 95% CI: -2.19, -0.45 kg) and whether 1 meal/d probably reduces FM compared with 3 meals/d (MD: -1.84 kg; 95% CI: -3.72, 0.05 kg; very low certainty of evidence). Two meals per day compared with 6 meals/d probably reduce WC (MD: -3.77 cm; 95% CI: -4.68, -2.86 cm; moderate certainty of evidence). One meal per day was ranked as the best frequency for reducing BW (P-score: 0.81), followed by 2 meals/d (P-score: 0.74), whereas 2 meals/d performed best for WC (P-score: 0.96). EI was not affected by meal frequency. In conclusion, our findings indicate that there is little robust evidence that reducing meal frequency is beneficial.

Impact of Bean Consumption on Nutritional Outcomes amongst Adolescents

Brazilian adolescents have undergone a noteworthy nutritional epidemiological transition. There is an increase in the prevalence of overweight and high consumption of ultra-processed foods in parallel with patterns of traditional meals that include beans. This study analyzed associations between bean consumption in the diet of adolescents and nutrition outcomes. Multiple regression analysis showed a significant reduction in body mass index (BMI), body fat percentage (%BF) and LDL-cholesterol (LDL-c) values among those with bean consumption equal to or greater than five times a week. Adolescents who had lunch outside the home and those who did not have the habit of having lunch showed a significantly higher BMI. There was an increase in the %BF among married adolescents and those who did not have lunch. There was a reduction of LDL-c among those with intermediate per capita income and those who consumed processed juice less than 5 times a week, and an increase among those who did not have breakfast. There were significant interactions between sexual maturation, energy consumption, physical activity and energy consumption. Thus, in the context of this study, the presence of beans in the diet, at frequencies equal to or greater than five times a week, can be considered a proxy for healthy eating.

Effects of 6 vs 3 eucaloric meal patterns on glycaemic control and satiety in people with impaired glucose tolerance or overt type 2 diabetes: A randomized trial

BACKGROUND/OBJECTIVES

The study aimed to compare the effects of two eucaloric meal patterns (3 vs 6 meals/day) on glycaemic control and satiety in subjects with impaired glucose tolerance and plasma glucose (PG) levels 140-199mg/dL at 120min (IGT-A) or PG levels 140-199mg/dL at 120min and >200mg/dL at 30/60/90min post-oral glucose load on 75-g OGTT (IGT-B), or overt treatment-naïve type 2 diabetes (T2D).

SUBJECTS/METHODS

In this randomized crossover study, subjects with IGT-A (n=15, BMI: 32.4±5.2kg/m²), IGT-B (n=20, BMI: 32.5±5kg/m²) or T2D (n=12, BMI: 32.2±5.2kg/m²) followed a weight-maintenance diet (45% carbohydrates, 20% proteins, 35% fats) in 3 or 6 meals/day (each intervention lasting 12 weeks). Anthropometrics, diet compliance and subjective appetite were assessed every 2 weeks. OGTT and measurements of HbA1c and plasma lipids were performed at the beginning and end of each intervention period.

RESULTS

Body weight and physical activity levels remained stable throughout the study. In T2D, HbA1c and PG at 120min post-OGTT decreased with 6 vs 3 meals (P<0.001 vs P=0.02, respectively). The 6-meal intervention also improved post-OGTT hyperinsulinaemia in IGT-A subjects and hyperglycaemia in IGT-B subjects. In all three groups, subjective hunger and desire to eat were reduced with 6 vs 3 meals/day (P<0.05). There were no differences in HOMA-IR or plasma lipids between interventions.

CONCLUSION

Although weight loss remains the key strategy in hyperglycaemia management, dietary measures such as more frequent and smaller meals may be helpful for those not sufficiently motivated to adhere to calorie-restricted diets. Our study shows that 6 vs 3 meals a day can increase glycaemic control in obese patients with early-stage T2D, and may perhaps improve and/or stabilize postprandial glucose regulation in prediabetes subjects.

Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention: A Scientific Statement From the American Heart Association

Eating patterns are increasingly varied. Typical breakfast, lunch, and dinner meals are difficult to distinguish because skipping meals and snacking have become more prevalent. Such eating styles can have various effects on cardiometabolic health markers, namely obesity, lipid profile, insulin resistance, and blood pressure. In this statement, we review the cardiometabolic health effects of specific eating patterns: skipping breakfast, intermittent fasting, meal frequency (number of daily eating occasions), and timing of eating occasions. Furthermore, we propose definitions for meals, snacks, and eating occasions for use in research. Finally, data suggest that irregular eating patterns appear less favorable for achieving a healthy cardiometabolic profile. Intentional eating with mindful attention to the timing and frequency of eating occasions could lead to healthier lifestyle and cardiometabolic risk factor management.

Daily meal frequency and associated variables in children and adolescents

OBJECTIVE

To investigate the frequency distribution of daily meals and its relation to demographic, socioeconomic, behavioral, anthropometric and biochemical factors in children and adolescents.

METHODS

This was a cross-sectional study with a representative sample of 708 schoolchildren aged 7-14 years. Data on personal information, socioeconomic status, physical activity and number of meals were obtained through semi-structured questionnaire and consumption by 24-h recall and food record. Weight and height measurements were also performed to calculate the body mass index. Finally, blood samples were collected for analysis of total cholesterol, high- and low density lipoprotein, triglyceride, and glucose levels. Descriptive statistics, the Mann-Whitney test, and Poisson regression were used in statistical analysis.

RESULTS

Meal frequency <4 was associated in children, family income <3 Brazilian minimum wages (PR=5.42; 95% CI: 1.29-22.77; p=0.021) and adolescents, the number of sons in the family >2 (PR=1.53; 95% CI: 1.11-2.11; p=0.010). Even in the age group of 10-14 years, <4 meals was related to higher prevalence of body mass index (PR=1.33; 95% CI: 1.02-1.74; p=0.032) and low-density lipoprotein (PR=1.39; 95% CI: 1.03-1.87; p=0.030) higher after adjustments.

CONCLUSION

Lower frequency of meals was related to lower income in children and adolescents, larger number of sons in the family, and increased values of body mass index and low-density lipoprotein.

Randomized Trial Testing the Effects of Eating Frequency on Two Hormonal Biomarkers of Metabolism and Energy Balance

BACKGROUND

Eating frequency (EF) may influence obesity-related disease risk by attenuating postprandial fluctuations in hormones involved in metabolism, appetite regulation, and inflammation.

MATERIALS/METHODS

This randomized crossover intervention trial tested the effects of EF on fasting plasma insulin-like growth factor-I (IGF-1) and leptin. Fifteen subjects (4 males, 11 females) completed two eucaloric intervention phases lasting 21 days each: low EF ("low-EF"; 3 eating occasions/day) and high EF ("high-EF"; 8 eating occasions/day). Subjects were free-living and consumed their own meals using individualized structured meal plans with instruction from study staff. Subjects completed fasting blood draws and anthropometry on the first and last day of each study phase. The generalized estimated equations modification of linear regression tested the intervention effect on fasting serum IGF-1 and leptin.

RESULTS

Mean (± SD) age was 28.5 ± 8.70 years, and mean (± SD) Body Mass Index was 23.3 (3.4) kg/m². We found lower mean serum IGF-1 following the high-EF condition compared to the low-EF condition (P < 0.001). There was no association between EF and plasma leptin (P = 0.83).

CONCLUSION

These results suggest that increased EF may lower serum IGF-1, which is a hormonal biomarker linked to increased risk of breast, prostate, and colorectal cancer.

Dietary Factors in Reducing Risk of Cardiovascular Diseases

Diet influences many modifiable risk factors for cardiovascular diseases (CVDs). Considering this, moderation of total dietary fat, particularly trans and saturated fats, as well as cholesterol is recommended. Dietary fats should come mainly from plants and fatty fish, providing monounsaturated and polyunsaturated (including omega-3) fatty acids. Carbohydrate sources to emphasize include whole grains, legumes, vegetables, fruits, and other fiber-rich sources, rather than sugars. Although vitamins such as E, C, and some B vitamins are associated with reduced CVD risk, data do not support the use of supplements, but foods rich in these nutrients are advocated. Dietary minerals such as potassium, magnesium, and calcium may be beneficial to heart health, while reduction of dietary sodium decreases risk of hypertension. A large variety of phytonutrients are also associated with reduced CVD risk. Other dietary factors receiving research attention regarding CVD risk. Other dietary factors receiving research attention regarding CVD risk include caffeine, alcobol, and meal frequency, although more work is needed in these areas. In contrast, data are quite robust to support the importance of healthy body weight management in cardiovascular health. In general, diets based on a variety of less processed foods, mainly of plant origin, in the context of an active lifestyle, are conducive to heart health.

Eating frequency predicts new onset hypertension and the rate of progression of blood pressure, arterial stiffness, and wave reflections

BACKGROUND

Cross-sectional evidence indicates that eating frequency correlates with blood pressure, hypertension, and related target organ damage. The aim of the present study was to prospectively assess eating frequency as a predictor of arteriosclerosis progression and new onset hypertension over a follow-up period of 5 years in adults without cardiovascular disease.

METHODS

Eating frequency among other dietary parameters was evaluated in 115 nondiabetic study participants from a general population sample (54 ± 9.1 years, 45 women) at a baseline visit. Metabolic parameters known to be associated with eating frequency, markers of arteriosclerosis, including augmentation index, pulse wave velocity, SBP, and DBP were evaluated in all volunteers at baseline and after a 5-year follow-up.

RESULTS

By applying linear mixed models analysis, it was found that a high eating frequency at baseline significantly correlated with the rate of progression of pulse wave velocity (β = 0.521, P = 0.004), augmentation index (β = 0.503, P = 0.01), SBP (β = 0.694, P < 0.001), and DBP (β = 0.477, P = 0.009) and the incidence of new onset hypertension (odds ratio = 8.89, P < 0.001). After adjustment traditional cardiovascular risk factors, heart rate, homeostasis model assessment index of insulin resistance and total energy intake, the associations with augmentation index, SBP, DBP, and new onset hypertension remained significant.

CONCLUSION

In a population of nondiabetic adults without cardiovascular disease, eating frequency is associated with the rate of progression of wave reflections, blood pressure and of new onset hypertension. Interventional studies should confirm these data and possibly further assess the utility of eating behavior in the prevention of new onset hypertension and related target organ damage.

Energy and Nutrient Timing for Weight Control: Does Timing of Ingestion Matter?

Over the past 40 years, meal skipping and snacking in US adults have increased, and currently most eating occasions occur later in the day than previously. Whether these changes have played a causal role in the obesity epidemic is poorly understood. Observational studies are largely inconclusive due to methodological limitations. Experimental evidence does not support a causal role for eating frequency or breakfast skipping in weight control. Emerging evidence suggests that eating irregularity and eating later in the day may be detrimental for weight control, but more studies are needed. This article summarizes studies and highlights areas needing attention.

Sleep, circadian rhythm and body weight: parallel developments

Circadian alignment is crucial for body-weight management, and for metabolic health. In this context, circadian alignment consists of alignment of sleep, meal patterns and physical activity. During puberty a significant reduction in sleep duration occurs, and pubertal status is inversely associated with sleep duration. A consistent inverse association between habitual sleep duration and body-weight development occurs, independent of possible confounders. Research on misalignment reveals that circadian misalignment affects sleep-architecture and subsequently disturbs glucose–insulin metabolism, substrate oxidation, leptin- and ghrelin concentrations, appetite, food reward, hypothalamic–pituitary–adrenal-axis activity and gut-peptide concentrations enhancing positive energy balance and metabolic disturbance. Not only aligning meals and sleep in a circadian way is crucial, also regular physical activity during the day strongly promotes the stability and amplitude of circadian rhythm, and thus may serve as an instrument to restore poor circadian rhythms. Endogenicity may play a role in interaction of these environmental variables with a genetic predisposition. In conclusion, notwithstanding the separate favourable effects of sufficient daily physical activity, regular meal patterns, sufficient sleep duration and quality sleep on energy balance, the overall effect of the amplitude and stability of the circadian rhythm, perhaps including genetic predisposition, may integrate the separate effects in an additive way.

Effects of meal frequency on weight loss and body composition: a meta-analysis

It has been hypothesized that eating small, frequent meals enhances fat loss and helps to achieve better weight maintenance. Several observational studies lend support to this hypothesis, with an inverse relationship noted between the frequency of eating and adiposity. The purpose of this narrative review is to present and discuss a meta-analysis with regression that evaluated experimental research on meal frequency with respect to changes in fat mass and lean mass. A total of 15 studies were identified that investigated meal frequency in accordance with the criteria outlined. Feeding frequency was positively associated with reductions in fat mass and body fat percentage as well as an increase in fat-free mass. However, sensitivity analysis of the data showed that the positive findings were the product of a single study, casting doubt as to whether more frequent meals confer beneficial effects on body composition. In conclusion, although the initial results of this meta-analysis suggest a potential benefit of increased feeding frequencies for enhancing body composition, these findings need to be interpreted with circumspection.

Evidence for efficacy and effectiveness of changes in eating frequency for body weight management

In self-reported diets of free living individuals, frequent eating is associated with higher energy intake, yet beliefs about the possible beneficial effect of higher eating frequency for managing body weight persist. Prospective cohort studies and controlled trials of manipulation of eating frequency published by 31 December 2012 were reviewed to assess whether variation in eating frequency may be an adjunct to weight management. Four prospective cohort studies were identified; 2 of these included adults followed for 10 y and 2 followed pre-adolescent/adolescent girls for 6 or 10 y. Within each age category, the findings of the 2 studies were contradictory. Six controlled trials with adult subjects serving as their own controls found no significant changes in body weight due to manipulation of eating frequency interventions lasting 6-8 wk. In 6 additional intervention trials of 8-52 wk duration, free-living adults were counseled to change the eating frequency of self-selected food intake with no significant differences in weight loss attributable to eating frequency. Overall, the consistency of the null findings from controlled trials of manipulation of eating frequency for promoting weight loss suggests that beliefs about the role of higher eating frequency in adult weight management are not supported by evidence. Interpretation of the evidence from published observational studies is complicated by differences in definition of eating frequency and limited knowledge of systematic and random errors in measurement of eating frequency.

The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults

BACKGROUND

Popular beliefs that breakfast is the most important meal of the day are grounded in cross-sectional observations that link breakfast to health, the causal nature of which remains to be explored under real-life conditions.

OBJECTIVE

The aim was to conduct a randomized controlled trial examining causal links between breakfast habits and all components of energy balance in free-living humans.

DESIGN

The Bath Breakfast Project is a randomized controlled trial with repeated-measures at baseline and follow-up in a cohort in southwest England aged 21-60 y with dual-energy X-ray absorptiometry-derived fat mass indexes ≤11 kg/m² in women (n = 21) and ≤7.5 kg/m² in men (n = 12). Components of energy balance (resting metabolic rate, physical activity thermogenesis, energy intake) and 24-h glycemic responses were measured under free-living conditions with random allocation to daily breakfast (≥700 kcal before 1100) or extended fasting (0 kcal until 1200) for 6 wk, with baseline and follow-up measures of health markers (eg, hematology/biopsies).

RESULTS

Contrary to popular belief, there was no metabolic adaptation to breakfast (eg, resting metabolic rate stable within 11 kcal/d), with limited subsequent suppression of appetite (energy intake remained 539 kcal/d greater than after fasting; 95% CI: 157, 920 kcal/d). Rather, physical activity thermogenesis was markedly higher with breakfast than with fasting (442 kcal/d; 95% CI: 34, 851 kcal/d). Body mass and adiposity did not differ between treatments at baseline or follow-up and neither did adipose tissue glucose uptake or systemic indexes of cardiovascular health. Continuously measured glycemia was more variable during the afternoon and evening with fasting than with breakfast by the final week of the intervention (CV: 3.9%; 95% CI: 0.1%, 7.8%).

CONCLUSIONS

Daily breakfast is causally linked to higher physical activity thermogenesis in lean adults, with greater overall dietary energy intake but no change in resting metabolism. Cardiovascular health indexes were unaffected by either of the treatments, but breakfast maintained more stable afternoon and evening glycemia than did fasting.

Chronobiology, endocrinology, and energy- and food-reward homeostasis

Energy- and food-reward homeostasis is the essential component for maintaining energy balance and its disruption may lead to metabolic disorders, including obesity and diabetes. Circadian alignment, quality sleep and sleep architecture in relation to energy- and food-reward homeostasis are crucial. A reduced sleep duration, quality sleep and rapid-eye movement sleep affect substrate oxidation, leptin and ghrelin concentrations, sleeping metabolic rate, appetite, food reward, hypothalamic-pituitary-adrenal (HPA)-axis activity, and gut-peptide concentrations, enhancing a positive energy balance. Circadian misalignment affects sleep architecture and the glucose-insulin metabolism, substrate oxidation, homeostasis model assessment of insulin resistance (HOMA-IR) index, leptin concentrations and HPA-axis activity. Mood disorders such as depression occur; reduced dopaminergic neuronal signaling shows decreased food reward. A good sleep hygiene, together with circadian alignment of food intake, a regular meal frequency, and attention for protein intake or diets, contributes in curing sleep abnormalities and overweight/obesity features by preventing overeating; normalizing substrate oxidation, stress, insulin and glucose metabolism including HOMA-IR index, and leptin, GLP-1 concentrations, lipid metabolism, appetite, energy expenditure and substrate oxidation; and normalizing food reward. Synchrony between circadian and metabolic processes including meal patterns plays an important role in the regulation of energy balance and body-weight control. Additive effects of circadian alignment including meal patterns, sleep restoration, and protein diets in the treatment of overweight and obesity are suggested.

Less frequent eating predicts greater BMI and waist circumference in female adolescents

BACKGROUND

Little is known about the effect of eating frequency on adiposity.

OBJECTIVE

The study aim was to assess the prospective relation of an objective measure of eating frequency with adiposity in girls from ages 9-10 to 19-20 y.

DESIGN

By using data from 3-d diet records collected from 2372 girls in the National Heart, Lung, and Blood Institute Growth and Health Study, meal, snack, and total eating frequencies aggregated over the first 2 study years were examined in relation to 10-y change in BMI and waist circumference (WC).

RESULTS

Eating frequency was lower in black and older girls than in white and younger girls (P < 0.0001). In whites, lower initial snack and total eating frequencies were related to greater 10-y increases in BMI (P = 0.023 and 0.012, respectively) and WC (P = 0.030 and 0.015, respectively). In blacks, lower initial meal and snack frequencies were related to greater increases in BMI (P = 0.004 and 0.022, respectively) and WC (P = 0.052 and 0.005, respectively). Also, in blacks, lower initial total eating frequency was related to greater increases in WC (P = 0.010). After adjustment for baseline adiposity measure, race, parental education, physical activity, television and video viewing, total energy intake, and dieting for weight loss, lower initial total eating frequency remained related to greater 10-y increases in BMI (P = 0.013) and WC (P = 0.036).

CONCLUSIONS

A lower eating frequency predicts a greater gain in adiposity in adolescent females. Intervention trials are needed to test if changing the frequency of eating can affect obesity risk.

Bath Breakfast Project (BBP)--examining the role of extended daily fasting in human energy balance and associated health outcomes: study protocol for a randomised controlled trial [ISRCTN31521726]

BACKGROUND

Current guidance regarding the role of daily breakfast in human health is largely grounded in cross-sectional observations. However, the causal nature of these relationships has not been fully explored and what limited information is emerging from controlled laboratory-based experiments appears inconsistent with much existing data. Further progress in our understanding therefore requires a direct examination of how daily breakfast impacts human health under free-living conditions.

METHODS/DESIGN

The Bath Breakfast Project (BBP) is a randomised controlled trial comparing the effects of daily breakfast consumption relative to extended fasting on energy balance and human health. Approximately 70 men and women will undergo extensive laboratory-based assessments of their acute metabolic responses under fasted and post-prandial conditions, to include: resting metabolic rate, substrate oxidation, dietary-induced thermogenesis and systemic concentrations of key metabolites/hormones. Physiological and psychological indices of appetite will also be monitored both over the first few hours of the day (i.e. whether fed or fasted) and also following a standardised test lunch used to assess voluntary energy intake under controlled conditions. Baseline measurements of participants' anthropometric characteristics (e.g. DEXA) will be recorded prior to intervention, along with an oral glucose tolerance test and acquisition of adipose tissue samples to determine expression of key genes and estimates of tissue-specific insulin action. Participants will then be randomly assigned either to a group prescribed an energy intake of ≥3000 kJ before 1100 each day or a group to extend their overnight fast by abstaining from ingestion of energy-providing nutrients until 1200 each day, with all laboratory-based measurements followed-up 6 weeks later. Free-living assessments of energy intake (via direct weighed food diaries) and energy expenditure (via combined heart-rate/accelerometry) will be made during the first and last week of intervention, with continuous glucose monitors worn both to document chronic glycaemic responses to the intervention and to verify compliance.

Eating frequency and energy regulation in free-living adults consuming self-selected diets

The relative importance of eating frequency to weight control is poorly understood. This review examines the evidence to date on the role of eating frequency in weight control in free-living adults. The majority of cross-sectional studies in free-living adults show an inverse relationship between eating frequency and adiposity; however, this is likely an artifact produced by the underreporting of eating frequency concurrent with underreporting of energy intake. When implausible energy intake reporting (which is mostly underreporting) is taken into account, the association between eating frequency and adiposity becomes positive. In studies in which eating frequency is prescribed and food intake is mostly self-selected, there is either no effect or a minor positive effect of eating frequency on energy intake. Most of those studies have been short-term and lack the necessary dietary biomarkers to validate reported energy intakes and eating frequencies. In conclusion, there is some suggestion from cross-sectional studies in which energy intake underreporting is taken into account and from experimental studies to date that greater eating frequency may promote positive energy balance. However, experimental studies of longer-term duration that include objective dietary biomarkers are necessary before firm conclusions about the relative importance of eating frequency in weight control can be made.

Chronobiological aspects of food intake and metabolism and their relevance on energy balance and weight regulation

Overweight and obesity are the result of a chronic positive energy balance, and therefore the only effective therapies are a diet which, on the long term, provides lower calories than the daily expended energy and exercise. Because nearly every physiological and biochemical function of the body shows circadian variations it can be suggested that also different chronobiological aspects of food intake, like time of day, meal frequency and regularity, and also circadian desynchronizations like in shift work may affect energy metabolism and weight regulation. The aim of this review is therefore to summarize and discuss studies that have addressed these issues in the past and to also provide an overview about circadian variations of selected aspects of metabolism, gut physiology and also factors that may influence overall energy regulation. The results show that a chronic desynchronization of the circadian system like in shift work and also sleep deprivation can favour the development of obesity. Also, regarding energy balance, a higher meal frequency and regular eating pattern seem to be more advantageous than taking the meals irregularly and seldom. Additional studies are required to conclude whether time of day-dependent food intake significantly influences weight regulation in humans.

Frequent cholesterol intake up-regulates intestinal NPC1L1, ACAT2, and MTP

Dietary cholesterol elevates plasma total cholesterol (TC) level. However, no study to date has examined how cholesterol intake frequency interacts with the gene of sterol transporters, receptors, and enzymes involved in cholesterol metabolism. Thirty-three hamsters were divided into three groups with the control hamsters being given daily 9 mg of cholesterol in the diet (CD), whereas the second group being gavage-administered 3 mg of cholesterol three times per day (C-3) and the third group being gavage-administered 9 mg of cholesterol one time per day (C-1). The experiment lasted for 6 weeks. The hamsters were killed under carbon dioxide suffocation. Data demonstrated that plasma TC, non-high-density lipoprotein cholesterol, and triacylglycerols were elevated with the increasing cholesterol intake frequency. Western blotting analyses revealed that the intake frequency had no effect on protein mass of hepatic sterol regulatory element binding protein-2, liver X receptor-alpha, 3-hydroxy-3-methylglutaryl-CoA reductase, LDL receptor, and cholesterol-7alpha-hydroxylase. However, the frequent cholesterol intake down-regulated the mRNA level of hepatic LDL receptor. In contrast, the frequent cholesterol intake up-regulated the mRNA levels of intestinal Niemann-Pick C1-like 1 (NPC1L1), acyl coenzyme A:cholesterol acyltransferase 2 (ACAT2), and microsomal triacylglycerol transport protein (MTP). It was concluded that the cholesterol intake frequency-induced elevation in plasma TC was associated with greater cholesterol absorption, possibly mediated by up-regulation of NPC1L1, ACAT2, and MTP.

Nibbling versus feasting: which meal pattern is better for heart disease prevention?

Dietary interventions that limit saturated fat, cholesterol, and energy are generally implemented as the first line of therapy to reduce the risk of coronary heart disease (CHD). Another form of diet therapy that may be effective in protecting against CHD is altering meal frequency without limiting energy. Meal-frequency regimens are classified into two major forms: 1) feasting, i.e., consuming all energy needs in one meal/day, and 2) nibbling, i.e., consuming all energy needs in three, six, nine, 12, or 17 regimented meals/day. Whether one meal pattern, feasting or nibbling, is more effective at improving indicators of CHD risk than the other, remains unresolved. Moreover, whether a dose-dependent relationship exists between biomarker improvement and the number of meals consumed per day also remains unknown. The objective of the present review was to determine which meal pattern, nibbling or feasting, is more effective at improving key indicators of CHD risk in normal-weight and obese, non-diabetic individuals.

Association between eating frequency, weight, and health

There is speculation amongst health professionals, the media, and the public regarding eating frequency (EF) and its impact on weight and health. Nutritional weight-loss and -maintenance interventions of longer than 1 week's duration were reviewed for associations between EF and weight and health. Of the 176 studies identified, 25 relevant studies matched the criteria and only 10 of these were weight-loss interventions. Generally, sample sizes were small, interventions were short-term, and a wide array of definitions was used to define an eating occasion. Several key outcomes such as physical activity, adherence to assigned EF, and hunger were often not measured. The limited evidence available suggests there is no association between EF and weight or health in either weight-loss or -maintenance interventions, with a possible inverse association between EF and lipids in weight-maintenance interventions. Longer term, larger studies that include important weight and health outcomes are needed.

Diabetes risk, low fitness, and energy insufficiency levels among children from poor families

BACKGROUND

Low-income populations have higher rates of type 2 diabetes and it is the hope of the investigators to increase support for the dissemination of evidence-based prevention programs aimed at children from poor families.

OBJECTIVE

To determine the prevalence of high blood glucose, obesity, low fitness, and energy insufficiency levels among children from poor families.

DESIGN

The cross-sectional study conducted in fall 2001 used fasting capillary glucose, body mass index, body fat, step test, and three 24-hour dietary recalls to assess diabetes risk factor levels.

SUBJECTS

Participants were 1,402 fourth-grade students aged 8 to 10 years. The racial/ethnic backgrounds were 80% Mexican American, 10% African American, 5% Asian American, and 5% non-Hispanic white.

STATISTICAL ANALYSIS PERFORMED

All data were analyzed for descriptive statistics and frequencies of distribution. Means were computed by sex for all diabetes risk factors and t test conducted to determine differences between sexes.

RESULTS

Nearly 75% of participants lived in households with <USD 20,400 annual income. Although 44% of students were energy insufficient, 33% were obese, and 7% had high blood glucose levels. Most of these students had marginal to unacceptable fitness levels and consumed high energy-dense and low nutrient-dense foods.

CONCLUSIONS

Children living in poverty have high levels of diabetes risk factors and need early detection and intervention programs. Prudent advice might be to increase physical activity and intake of nutrient-dense foods rather than to restrict energy intake.

Eating meals irregularly: a novel environmental risk factor for the metabolic syndrome

BACKGROUND

Skipping meals is a common practice in our current society; however, it is not clear whether eating meals regularly is associated with the metabolic syndrome.

OBJECTIVE

Our aim was to assess the association of eating meals regularly with parameters of the metabolic syndrome and insulin resistance in a representative population-based cohort of 60-year-old men and women.

METHODS AND PROCEDURES

A population-based cross-sectional study of 3,607 individuals (1,686 men and 1,921 women), aged 60 years, was conducted in Stockholm County, Sweden. Medical history, socioeconomic factors, and lifestyle data were collected by a questionnaire and a medical examination, which included laboratory tests.

RESULTS

Of the subjects who were regular eaters, 20% fulfilled the criteria for the metabolic syndrome vs. 27% of subjects who were irregular eaters (P < 0.0001). The adjusted odds ratio (OR) for having the greatest number of components of the metabolic syndrome in subjects who were regular eaters was 0.27 (95% confidence interval (CI), 0.13-0.54) using subjects who did not fulfill any criteria for the metabolic syndrome as a reference group. Eating meals regularly was also inversely related to insulin resistance (OR, 0.68 (95% CI, 0.48-0.97)) and to gamma-glutamyl transferase (OR, 0.52 (95% CI, 0.33-83)) after full adjustment.

DISCUSSION

Eating meals regularly is inversely associated to the metabolic syndrome, insulin resistance and (high) serum concentrations of gamma-glutamyl transferase. These findings suggest that eating meals irregularly may be part of several potential environmental risk factors that are associated with the metabolic syndrome and may have future implications in giving dietary advice to prevent and/or treat the syndrome.

Nutrition Review: Diet and Metabolic Syndrome

Since most components of metabolic syndrome are related to lifestyle, exercise and diet are critical aspects of treatment. Most patients will need to reduce body weight. Some flexibility in dietary macronutrients is allowed, depending on the patient's metabolic profile and responsiveness. Types of fats and carbohydrates are particularly important. Artificial trans fats should be eliminated as much as possible and saturated fats minimized. Carbohydrates should be mainly unrefined and unprocessed, emphasizing fiber and low glycemic index, while keeping added sugars low. Monounsaturated fats are the best replacements for saturated fats and refined carbohydrates within energy and total fat limits. Micronutrients that may be beneficial for metabolic syndrome include vitamin D, calcium, magnesium, and potassium from whole food sources. Excess sodium chloride, as well as meal skipping, should be avoided.

Effect of nibbling and gorging dietary regimens on weight and lipid profile in rat

To investigate the effects of nibbling and gorging dietary regimens on weight and lipid profiles in rat, thirty female Wistar rats, after 10 day acclimatization period, were weighed and randomly assigned into two equal groups. They were fed the same food for 60 days as eight meals at 2 h intervals starting from 6 pm (nibbling group) or as two meals at 9 pm and 6 am (gorging group). The serum lipid levels and weight of animals were determined before and after the intervention. The body weight in two groups increased significantly (p < 0.001) during the period of study but there was no significant (p > 0.05) difference between two groups before and after the intervention. Nibbling regimen caused a reduction in the serum Total Cholesterol (TC), triglyceride and LDL-C levels, whereas these parameters increased during gorging diet. However, none of these changes were significant. There was a significant decrease (p < 0.05) in TC and LDL-C levels in nibbling diet compared to gorging one. According to obtained results, nibbling regimen has better effect on lipid profile than gorging one in rat.

Carbohydrate digestibility and metabolic effects

There is a history of interest in the metabolic effects of alterations in small intestinal digestion and colonic fermentation of carbohydrate. It is believed that the rate of digestion of carbohydrate determines the place and form in which carbohydrate is absorbed. Slowly absorbed or lente carbohydrate sources may reduce postprandial glucose surges and the need for insulin with important implications for lowering coronary heart disease risk and reducing diabetes incidence. Carbohydrates that are not digested in the small intestine will enter the colon, and those that are fermentable will be salvaged as short-chain fatty acids in the colon and at the same time may stimulate colonic microflora, such as bifidobacteria. This process may have metabolic effects in the gut and throughout the host, possibly related to short-chain fatty acid products, although these effects are less well documented. One important aspect of colonic fermentation is the stimulation of certain populations of the colonic microflora, which may assist in the biotransformation of bioactive food components including the cleaving of plant phenolics from their glycone to produce the more rapidly absorbed aglycone. However, human studies have been limited. Therefore, further studies are required to explore these important aspects of metabolism related to the rate of carbohydrate absorption and fermentation and their implications in health and disease.

Should snacks be recommended in obesity treatment? a 1-year randomized clinical trial

OBJECTIVE

To study the effect to recommend no snacks vs three snacks per day on 1-year weight loss. The hypothesis was that it is easier to control energy intake and lose weight if snacks in between meals are omitted.

SUBJECTS/METHOD

In total 140 patients (36 men, 104 women), aged 18-60 years and body mass index>30 kg/m(2) were randomized and 93 patients (27 men, 66 women) completed the study. A 1-year randomized intervention trial was conducted with two treatment arms with different eating frequencies; 3 meals/day (3M) or 3 meals and 3 snacks/day (3+3M). The patients received regular and individualized counseling by dieticians. Information on eating patterns, dietary intake, weight and metabolic variables was collected at baseline and after 1 year.

RESULTS

Over 1 year the 3M group reported a decrease in the number of snacks whereas the 3+3M group reported an increase (-1.1 vs +0.4 snacks/day, respectively, P<0.0001). Both groups decreased energy intake and E% (energy percent) fat and increased E% protein and fiber intake but there was no differences between the groups. Both groups lost weight, but there was no significant difference in weight loss after 1 year of treatment (3M vs 3+3M=-4.1+/-6.1 vs -5.9+/-9.4 kg; P=0.31). Changes in metabolic variables did not differ between the groups, except for high-density lipoprotein that increased in the 3M group but not in 3+3M group (P<0.033 for group difference).

CONCLUSION

Recommending snacks or not between meals does not influence 1-year weight loss.

Chronically gorgingv. nibbling fat and cholesterol increases postprandial lipaemia and atheroma deposition in the New Zealand White rabbit

In the present study, we compared the effects of nibbling and gorging on postprandial lipaemia and lipoproteins, hepatic lipid uptake and atheroma deposition. New Zealand White rabbits were fed on a low-fat (LF) control diet or a peanut oil- (10 g/d) and cholesterol- (0·5 g/d) enriched (HF) diet with the fat and cholesterol components given either by nibbling (HF-N) or gorging (HF-G). After 4 and 8 weeks, rabbits were given a test meal, which was either nibbled or taken as a bolus. The LF diet did not noticeably alter postprantial lipid variables. Triacylglycerol levels, 0–35 h lipid responses and plasma accumulation of dietary lipids were significantly higher in the HF-G group than in the HF-N group, despite higher post-heparin plasma lipase activities. Furthermore, as studied on cultured isolated hepatocytes, the higher the rate of supply of triacylglycerol- and cholesterol-rich lipoproteins (TCRL), the lower the rate of lipid uptake and bile salt secretion. Atheroma deposition was significantly increased by gorging the HF diet and was correlated with levels of most postprandial lipid variables. We conclude that gorgingv. nibbling a fat and cholesterol-enriched diet exacerbates postprandial lipaemia by reducing the rate of TCRL clearance and favours atheroma deposition.

An experimental test of the effects of dieting on bulimic symptoms: The impact of eating episode frequency

Prospective studies suggest dieting increases bulimic symptoms, but experiments suggest that dieting decreases bulimic symptoms. One possible explanation for the conflicting findings is that real world dieting involves less healthy dieting techniques, such as meal skipping, than prescribed diets. We tested whether the manipulation of eating episode frequency during dieting impacted bulimic symptoms. We expected that people on a diet involving fewer eating episodes would exhibit greater increases in bulimic symptoms than people on a diet involving more frequent eating episodes or waitlist controls. Participants on both 6-week diets lost more weight than controls, confirming dieting was manipulated, and showed greater reductions in bulimic symptoms than controls; however, the dieting conditions did not differ on either outcome. Results provide further experimental evidence that dieting does not increase bulimic symptoms, but suggests that eating episode frequency has little impact on this outcome.

Consequence of omitting or adding a meal in man on body composition, food intake, and metabolism

OBJECTIVE

To investigate in man the consequence on body composition and related biological and metabolic parameters of omitting or adding a meal.

RESEARCH METHODS AND PROCEDURES

Twenty-four young normal-weight male subjects were recruited, 12 usual four-meal and 12 usual three-meal eaters, differing only in the consumption of an afternoon meal. They omitted or added a fourth meal during a 28-day habituation period and were asked to report their intake on three 3-day occasions. Before and after this habituation period, subjects participated in a session with a time-blinded procedure, and blood was collected continuously from lunch to the spontaneously requested dinner. Body composition, respiratory quotient, and biochemical parameters were measured in the late evening preceding each session.

RESULTS

Omitting a meal was followed by increases in fat mass (360 +/- 115 grams, p < 0.05), late evening leptin concentration (20.7 +/- 11.0%, p < 0.05), and respiratory quotient (3.7 +/- 1.4%, p < 0.05). Increase in the percentage of dietary fat during the habituation period (+4.1 +/- 2.0%, p < 0.05) was correlated with fat mass (r = 0.66, p < 0.05). Adding a meal had no effect, but, in both groups, the change in energy content at this fourth eating occasion was correlated with the change in adiposity.

DISCUSSION

Our results suggest that adiposity may increase when young lean male subjects switch from a four- to a three-meal pattern by removing their usual afternoon meal. This effect could be partly mediated by a change in the macronutrient composition of the diet.

Beneficial metabolic effects of regular meal frequency on dietary thermogenesis, insulin sensitivity, and fasting lipid profiles in healthy obese women

BACKGROUND

Although a regular meal pattern is recommended for obese people, its effects on energy metabolism have not been examined.

OBJECTIVE

We investigated whether a regular meal frequency affects energy intake (EI), energy expenditure, or circulating insulin, glucose, and lipid concentrations in healthy obese women.

DESIGN

Ten women [x +/- SD body mass index (in kg/m(2)): 37.1 +/- 4.8] participated in a randomized crossover trial. In phase 1 (14 d), the subjects consumed their normal diet on 6 occasions/d (regular meal pattern) or followed a variable meal frequency (3-9 meals/d, irregular meal pattern). In phase 2 (14 d), the subjects followed the alternative pattern. At the start and end of each phase, a test meal was fed, and blood glucose, lipid, and insulin concentrations were determined before and for 3 h after (glucose and insulin only) the test meal. Subjects recorded their food intake on 3 d during each phase. The thermogenic response to the test meal was ascertained by indirect calorimetry.

RESULTS

Regular eating was associated with lower EI (P < 0.01), greater postprandial thermogenesis (P < 0.01), and lower fasting total (4.16 compared with 4.30 mmol/L; P < 0.01) and LDL (2.46 compared with 2.60 mmol/L; P < 0.02) cholesterol. Fasting glucose and insulin values were not affected by meal pattern, but peak insulin concentrations and area under the curve of insulin responses to the test meal were lower after the regular than after the irregular meal pattern (P < 0.01 and 0.02, respectively).

CONCLUSION

Regular eating has beneficial effects on fasting lipid and postprandial insulin profiles and thermogenesis.

Fracionamento das refeições e colesterol sérico em mulheres com dieta adicionada de frutas ou fibras

OBJETIVO: Estudos epidemiológicos têm mostrado uma relação inversa entre a freqüência habitual de refeições e colesterol total no sangue, sugerindo que o padrão alimentar pode modular esse lipídio. O objetivo desta pesquisa foi avaliar o efeito do fracionamento das refeições com a adição de frutas ou fibra sobre o colesterol sérico, utilizando o banco de dados de um ensaio clínico. MÉTODOS: Testou-se o efeito da adição de frutas ou fibras na dieta de 49 mulheres com excesso de peso (IMC>25kg/m²), não fumantes, na faixa etária de 30 a 50 anos, e com colesterol sérico maior ou igual a 240mg/dL. As mulheres, alocadas randomicamente, receberam maçã (300g), pêra (300g), ou biscoitos de aveia (60g) com igual teor de fibra, por dez semanas. No início do estudo, a freqüência de refeições foi de 3,8±1,1 e, no transcorrer do estudo, aumentou-se o número de refeições diárias para cinco. Foi então avaliada a variação no colesterol sérico segundo modificação no número de refeições diárias, calculada pela diferença entre o número de refeições no início do estudo e o número de refeições na 14ª semana de intervenção. Este aumento de refeições foi categorizado em: uma, duas, três ou mais refeições diárias. RESULTADOS: Após 14 semanas de seguimento, observou-se que houve redução de 12,6mg/dL, p<0,04 e 17,4mg/dL, p<0,03, respectivamente, no colesterol total e no LDL-C sérico das participantes que relataram aumento médio de três ou mais refeições diárias. Quando o modelo foi ajustado para idade, peso corporal e tipo de alimento adicionado à dieta (maçã, pêra ou aveia), as reduções foram menores (11,5mg/dL, p<0,04; 17,3, p<0,04); entretanto, a diferença continuou estatisticamente significante para as participantes que reportaram aumento médio de três ou mais refeições. O nível de HDL-C não mostrou alteração antes e após ajuste. CONCLUSÃO: O fracionamento das refeições reduziu o colesterol total e LDL-C sérico em mulheres hipercolesterolêmicas, independente da idade, peso corporal e tipo de alimento ingerido, frutas ou fibras, sugerindo que o número de seis refeições diárias poderia ser uma medida de prevenção e controle da hipercolesterolemia.

Regular meal frequency creates more appropriate insulin sensitivity and lipid profiles compared with irregular meal frequency in healthy lean women

OBJECTIVE

To investigate the impact of irregular meal frequency on circulating lipids, insulin, glucose and uric acid concentrations which are known cardiovascular risk factors.

DESIGN

A randomised crossover dietary intervention study.

SETTING

Nottingham, UK--Healthy free-living women.

SUBJECTS

A total of nine lean healthy women aged 18-42 y recruited via advertisement.

INTERVENTION

A randomised crossover trial with two phases of 14 days each. In Phase 1, subjects consumed their normal diet on either 6 occasions per day (regular) or by following a variable meal frequency (3-9 meals/day, irregular). In Phase 2, subjects followed the alternative meal pattern to that followed in Phase 1, after a 2-week (wash-out) period. Subjects were asked to come to the laboratory after an overnight fast at the start and end of each phase. Blood samples were taken for measurement of circulating glucose, lipids, insulin and uric acid concentrations before and for 3 h after consumption of a high-carbohydrate test meal.

RESULTS

Fasting glucose and insulin values were not affected by meal frequency, but peak insulin and AUC of insulin responses to the test meal were higher after the irregular compared to the regular eating patterns (P < 0.01). The irregular meal frequency was associated with higher fasting total (P < 0.01) and LDL (P < 0.05) cholesterol.

CONCLUSION

The irregular meal frequency appears to produce a degree of insulin resistance and higher fasting lipid profiles, which may indicate a deleterious effect on these cardiovascular risk factors.

SPONSORSHIP

: The Ministry of Health and Medical Education, IR Iran.

Children's meal patterns have changed over a 21-year period: the Bogalusa Heart Study

OBJECTIVE

The objective of this study was to analyze children's meal patterns over 2 decades.

DESIGN

One 24-hour dietary recall was collected on each child who participated in one of seven cross-sectional surveys.

SUBJECTS/SETTING

Dietary intake data were collected on 1,584 10-year-old children (65% white, 35% African American), in Bogalusa, LA, from 1973 to 1994.

STATISTICAL ANALYSES

Descriptive statistics and one-way analysis of variance adjusting for gender and ethnicity.

RESULTS

From 1973 to 1978, there was a marked increase (P<.0001) in the percentage of children who skipped breakfast, from 8.2% to 29.6%. When school breakfast was introduced in 1981, the proportion of children skipping breakfast declined to 12.5% (P<.01). From 1973-1974 to 1993-1994, the percentage of children eating a school lunch declined from 89.7% (1973-1974) to 78.2% (1993-1994) (P<.001); eating lunch brought from home increased from 5.9% to 11.1% (P<.01); consuming a home dinner decreased from 89.2% to 75.9% (P<.01); eating a dinner prepared outside the home increased from 5.4% to 19.0% (P<.01); consuming a meal at a restaurant increased from 0.3% to 5.4% (P<.0001); consuming snacks decreased (P<.0001); total eating episodes decreased from 6.6 to 5.2 (P<.0001); and eating time span significantly decreased from 12.4 hours to 11.5 hours (P<.0001). Despite these changes in meal patterns, no associations were found between meal patterns and overweight status.

CONCLUSIONS

Striking alterations in the meal patterns of children occurred over the 2-decade period. These changes may have implications for the changes in the dietary intakes of children during the same time. However, data from this study do not support an association between meal patterns and children's overweight status. Further research with multiple days of assessment is needed to better understand the complexity of diet as it relates to childhood obesity.

Decreased thermic effect of food after an irregular compared with a regular meal pattern in healthy lean women

OBJECTIVES

To investigate the impact of irregular meal frequency on body weight, energy intake, appetite and resting energy expenditure in healthy lean women.

DESIGN

Nine healthy lean women aged 18-42 y participated in a randomised crossover trial consisting of three phases over a total of 43 days. Subjects attended the laboratory at the start and end of phases 1 and 3. In Phase 1 (14 days), subjects were asked to consume similar things as normal, but either on 6 occasions per day (regular meal pattern) or follow a variable predetermined meal frequency (between 3 and 9 meals/day) with the same total number of meals over the week. In Phase 2 (14 days), subjects continued their normal diet as a wash-out period. In Phase 3 (14 days), subjects followed the alternative meal pattern to that followed in Phase 1. Subjects recorded their food intake for three predetermined days during the irregular period when they were eating 9, 3 and 6 meals/day. They also recorded their food intake on the corresponding days during the regular meal pattern period. Subjects fasted overnight prior to each laboratory visit, at which fasting resting metabolic rate (RMR) was measured by open-circuit indirect calorimetry. Postprandial metabolic rate was then measured for 3 h after the consumption of a milkshake test meal (50% CHO, 15% protein and 35% fat of energy content). Subjects rated appetite before and after the test meal.

RESULTS

There were no significant differences in body weight and 3-day mean energy intake between the regular and irregular meal pattern. In the irregular period, the mean energy intake on the day when 9 meals were eaten was significantly greater than when 6 or 3 meals were consumed (P=0.0001). There was no significant difference between the 3 days of the regular meal pattern. Subjective appetite measurement showed no significant differences before and after the test meal in all visits. Fasting RMR showed no significant differences over the experiment. The overall thermic effect of food (TEF) over the 3 h after the test meal was significantly lower after the irregular meal pattern (P=0.003).

CONCLUSION

Irregular meal frequency led to a lower postprandial energy expenditure compared with the regular meal frequency, while the mean energy intake was not significantly different between the two. The reduced TEF with the irregular meal frequency may lead to weight gain in the long term.

High-complex carbohydrate or lente carbohydrate foods?

Current dietary guidelines of the American Diabetes Association emphasize the importance of minimizing risk factors for cardiovascular disease while maximizing diabetes control. Potential advantages are seen for increased monounsaturated fat intake, but only the quantity rather than the quality of the carbohydrate is considered important. However, review of the carbohydrate issue suggests that many cultures now at high risk of diabetes originally consumed starchy staples higher in fiber and with a lower glycemic index than eaten currently. Furthermore, diets high in cereal fiber have been associated with improved glycemic control, and low glycemic index diets resulted in reduction in glycosylated proteins in type 1 and 2 diabetes. Finally, large cohort studies have demonstrated beneficial effects of cereal fiber and low glycemic index carbohydrate foods in reducing the risk both for diabetes and cardiovascular disease. The effect of insoluble cereal fiber is not readily explained, but a low glycemic index may result from a slower rate of carbohydrate absorption. Increased meal frequency as a model for reducing the rate of carbohydrate absorption has been shown to reduce day-long glucose and insulin levels in type 2 diabetes and reduce serum lipids in nondiabetic subjects. Therefore, there appears to be a potential role for low glycemic index, high-cereal fiber foods for prevention and treatment of diabetes. Both the nature of the dietary fat and the carbohydrate should be considered as potentially modifiable factors that together with weight control and exercise may play a role in diabetes and cardiovascular disease prevention and treatment.