An update on low-carbohydrate, high-protein diets

Dietary Models and Cardiovascular Risk Prevention in Pediatric Patients

Nutritional intervention is worldwide recognized as a first step treatment for subjects with increased cardiovascular risk and it is of utmost importance especially for children and adolescents. Currently scientific evidence supports the role of dietary patterns instead of simple single nutrients or foods in cardiovascular risk prevention. Indeed, the American Heart Association dietary guidelines have expanded beyond nutrients to dietary pattern, that comprise not only single food items but also behavioral or cultural habits of specific populations. The aim of our narrative review is to analyze the most frequently adopted dietary patterns in children and adolescents and to evaluate their effect on cardiovascular risk factors and in cardiovascular risk prevention. Literature review showed that children cannot be considered as little adults: nutritional intervention must always grant adequate growth and neurodevelopment before reaching the proposed goals, therefore dietary patterns considered heart-healthy for adult subjects might not be suitable for pediatric patients. Mediterranean diet, DASH diet, Nordic diet and some plant-based diets seem to be the most promising dietary patterns in terms of cardiovascular health in the developmental age, even if further studies are needed to better standardize and analyze their effect on growing up individuals.

Factors Associated With Treatment Adherence to a Lifestyle Intervention Program for Children With Obesity: The Experience of a Large Tertiary Care Pediatric Hospital

Early dropout and treatment adherence are main challenges in the treatment of children with obesity. The aim of this study was to identify factors associated with attrition and adherence to weight loss intervention program. We retrospectively reviewed the medical records of all the children who entered the program for pediatric weight loss over 5 years and retrieved demographic and clinical characteristics. Attrition and adherence were documented. Ninety-two of the 248 enrolled children (52% women, mean age 11.1 ± 3.9 years, mean body mass index 31.1 ± 7 kg/m²) dropped out (37%). Dropping out correlated with male sex, low parental education, and self-referral to the clinic (P < .05 for all). Adherence correlated with older age and the mother's healthy lifestyle (P < .05 for all). Sex, parental education, and referral source may predict treatment attrition. Early recognition of children at risk of attrition may help to facilitate better care of those children.

Effects of a high-protein, low-carbohydrate v. high-protein, moderate-carbohydrate weight-loss diet on antioxidant status, endothelial markers and plasma indices of the cardiometabolic profile

There are concerns that weight-loss (WL) diets based on very low carbohydrate (LC) intake have a negative impact on antioxidant status and biomarkers of cardiovascular and metabolic health. Obese men (n 16) participated in a randomised, cross-over design diet trial, with food provided daily, at approximately 8.3 MJ/d (approximately 70 % of energy maintenance requirements). They were provided with two high-protein diets (30 % of energy), each for a 4-week period, involving a LC (4 % carbohydrate) and a moderate carbohydrate (MC, 35 % carbohydrate) content. Body weight was measured daily, and weekly blood samples were collected. On average, subjects lost 6.75 and 4.32 kg of weight on the LC and MC diets, respectively (P < 0.001, SED 0.350). Although the LC and MC diets were associated with a small reduction in plasma concentrations of retinol, vitamin E (α-tocopherol) and β-cryptoxanthin (P < 0.005), these were still above the values indicative of deficiency. Interestingly, plasma vitamin C concentrations increased on consumption of the LC diet (P < 0.05). Plasma markers of insulin resistance (P < 0.001), lipaemia and inflammation (P < 0.05, TNF-α and IL-10) improved similarly on both diets. There was no change in other cardiovascular markers with WL. The present data suggest that a LC WL diet does not impair plasma indices of cardiometabolic health, at least within 4 weeks, in otherwise healthy obese subjects. In general, improvements in metabolic health associated with WL were similar between the LC and MC diets. Antioxidant supplements may be warranted if LC WL diets are consumed for a prolonged period.

Short-term carbohydrate-restricted diet for weight loss in severely obese women

BACKGROUND

Weight loss in bariatric pre-surgery period reduces surgical complications, surgery time, blood loss, and length of hospital stay. Carbohydrate-restricted diets have been used as an alternative for weight loss. We tested the efficacy of a low-calorie carbohydrate-restricted diet (RD) for short-term weight loss in women with severe obesity and evaluate its metabolic effects in relation to a conventional low-calorie diet (CD).

METHODS

The subjects received a 1,200-kcal diet with or without carbohydrate restriction for a period of 1 week in the hospital. Nineteen obesity class III women were distributed into two groups: experimental (n = 10) and control (n = 9). The following variables were assessed at the beginning and end of the study: anthropometric measurements, body composition, resting energy expenditure, substrate oxidation, and biochemical tests.

RESULTS

Compared with CD, RD led to larger weight loss (2.6 and 4.4 kg, respectively; p = 0.01) and waist circumference reduction (p < 0.01). Among the assessed biochemical indicators, only plasma and urine acetone levels were different (p < 0.01); higher values were found in the experimental group with no symptoms and other diet-related complaints. There was also a significant decrease in triglycerides and carbohydrate oxidation, as well as a significant enhancement in lipid oxidation in the RD group.

CONCLUSION

Short-term RD was more efficient than CD regarding quick weight loss and waist circumference reduction, which may favor gastroplasty. Also, RD did not lead adverse metabolic effects.

Effect of the protein:carbohydrate ratio in hypoenergetic diets on metabolic syndrome risk factors in exercising overweight and obese women

Overweight and obesity are growing problems both in Canada and around the world. Obesity is associated with a number of chronic diseases including type 2 diabetes and CVD, which puts a tremendous burden on the health care systems in place. The present study sought to investigate whether there were differences in the effectiveness of three low-fat, hypo- and isoenergetic diets differing in protein:carbohydrate ratio, low protein (LP, 1 g protein:4 g carbohydrate), normal protein (NP, 1 g protein:2 g carbohydrate) or high protein (HP, 1 g protein:1 g carbohydrate), on weight loss and markers of the metabolic syndrome (MetS) in overweight women. Subjects were randomly assigned to receive one of three intervention diets, all of which included a 60 min exercise programme three times/week for 12 weeks. Of the total subjects, fifty-four overweight and obese local women with MetS risk factors completed the study. All groups had similar improvements in body weight, insulin sensitivity, lipid profile, blood pressure and fitness. Subjects reported that the NP diet was easier to comply with and achieved better improvements in body fat, waist circumference and waist:hip ratio, and preservation of lean mass compared with the other two diets. In conclusion, energy restriction and exercise both facilitate weight loss in overweight and obese subjects and reduce symptoms of the MetS. A diet with a 1:2 protein:carbohydrate ratio promoted better improvements than either the LP or HP diets, and may be superior in reducing long-term chronic disease risk in this population.

Fiber, protein, and lupin-enriched foods: role for improving cardiovascular health

Cardiovascular diseases (CVD) are the leading cause of death globally (World Health Organisation, 2011). Many of the risk factors for CVD are modifiable, including overweight and obesity. Numerous strategies have been proposed to fight CVD, with a special focus being placed on dietary interventions for weight management. The literature suggests that two nutrients, fiber and protein, may play significant roles in weight control and hence cardiovascular health. Increasing both protein and fiber in the diet can be difficult because popular low-carbohydrate and high-protein diets tend to have considerably low-fiber intakes (Slavin, 2005). One approach to obtain both is to develop functional foods using unique ingredients. Lupin flour is a novel food ingredient derived from the endosperm of lupin. It contains 40-45% protein, 25-30% fiber, and negligible sugar and starch (Petterson and Crosbie, 1990). Research conducted to date reveals that lupin-enriched foods, which are naturally high in protein and fiber, may have a significant effect on CVD risk factors. This review explores whether there is a role for fiber-, protein-, and lupin-enriched foods in improving cardiovascular health.

Low-carbohydrate diets: a matter of love or hate

Low-carbohydrate diets (LChD) have become very popular among the general population. These diets have been used to lose body weight and to ameliorate various abnormalities like diabetes, nonalcoholic fatty liver disease, polycystic ovary syndrome, narcolepsy, epilepsy, and others. Reports suggest that body weight reduction and glycemic control could be attained while following LChD. However, these advantages are more notably found in short periods of time consuming an LChD. Indeed, the safety and efficacy of the latter diets in the long term have not been sufficiently explored. In contrast to what has been proposed, other mentioned pathologies are not improved or are even worsened by carbohydrate restriction. Therefore, the aim of this review is to define the concept of LChD and to explain their clinical effects in the short and long term, their influence on metabolism, and the opinion of nutrition or health authorities. Finally, evincing the research gaps of LChD that are here exposed will later allow us to reach a consensus with regard to their utilization.

Meta-analysis of studies of a specific delivery mode for a modified-carbohydrate diet

BACKGROUND

Obesity is highly prevalent throughout the world. Although modified-carbohydrate diets (MCDs) comprise one popular approach, questions remain about their utility for weight loss. The objective of the present study was to conduct a meta-analysis of randomised controlled trials (RCTs) of a specific MCD compared with various control diets on weight loss.

METHODS

Data from four RCTs (three obtained from the sponsor and one indentified through literature searches) were included. Intent-to-treat analyses were conducted using multiple imputation to handle missing data, where possible. Because inter-study heterogeneity was demonstrated with fixed-effects meta-analysis, a random-effects meta-analysis also was conducted.

RESULTS

When considered separately, all four studies showed greater reduction in body weight with the MCD compared to control diets at 12-week follow-up; the results at 24 weeks (available for three of the studies) were not as consistent. Results for body mass index (BMI) were similar. Greater reductions in waist circumference with the MCD were seen at either time point in only one study. When fixed-effects meta-analysis was applied, significantly greater reductions in weight, BMI and waist circumference with the MCD at both 12 weeks (1.66 kg, 0.53 kg m(-2) and 1.02 cm, respectively) and 24 weeks (1.20 kg, 0.43 kg m(-2) and 0.69 cm, respectively) were evident. Random-effects meta-analysis revealed similar results; however, the 24-week difference for a reduction in waist circumference was no longer statistically significant.

CONCLUSIONS

Meta-analysis of individual RCT results demonstrated consistent benefits of this MCD compared to control diets on weight loss up to 24 weeks and waist circumference up to 12 weeks.

Increased adipose tissue lipolysis after a 2-week high-fat diet in sedentary overweight/obese men

The purpose of this study was to determine if a high-fat diet would result in a higher lipolytic rate in subcutaneous adipose tissue than a lower-fat diet in sedentary nonlean men. Six participants (healthy males; 18-40 years old; body mass index, 25-37 kg/m(2)) underwent 2 weeks on a high-fat or well-balanced diet of similar energy content (approximately 6695 kJ) in randomized order with a 10-day washout period between diets. Subcutaneous abdominal adipose tissue lipolysis was determined over the course of a day using microdialysis after both 2-week diet sessions. Average interstitial glycerol concentrations (index of lipolysis) as determined using microdialysis were higher after the high-fat diet (210.8 ± 27.9 μmol/L) than after a well-balanced diet (175.6 ± 23.3 μmol/L; P = .026). There was no difference in adipose tissue microvascular blood flow as determined using the microdialysis ethanol technique. These results demonstrate that healthy nonlean men who diet on the high-fat plan have a higher lipolytic rate in subcutaneous abdominal adipose tissue than when they diet on a well-balanced diet plan. This higher rate of lipolysis may result in a higher rate of fat mass loss on the high-fat diet; however, it remains to be determined if this higher lipolytic rate in men on the high-fat diet results in a more rapid net loss of triglyceride from the abdominal adipose depots, or if the higher lipolytic rate is counteracted by an increased rate of lipid storage.

Energy density of foods, but not beverages, is positively associated with body mass index in adult women

Background/Objectives

Energy density (kJ/g) may have a strong influence on energy balance. Although beverages are a considerable source of energy in the US diet, rarely have studies among free-living populations investigated the energy density of foods (EDF) and the energy density of beverages (EDB) simultaneously. We examined the independent simultaneous associations of EDF and EDB on energy intake and Body Mass Index (BMI) in adult women.

Subjects/Methods

This cross-sectional design focused on 348 elementary school employees randomly selected at baseline of a worksite wellness trial in southeastern Louisiana. Two 24-hour recalls were collected, and measured heights and weights were converted into BMI (kg/m²).

Results

Those in the highest EDF tertile consumed more energy and had higher BMIs than those in the lowest tertile (P<0.05). Employees in the highest EDB tertile consumed more energy than those in the lowest, yet there was no difference in BMIs between the two groups. Multivariate regression, with controls for demographic and health variables, confirmed the positive association between EDF and BMI; a 1 kJ/g increase in EDF was associated with a 0.39 kg/m² increase in BMI (P=0.038). Models that did not control for EDB gave estimates of EDF that were 8% to 10% lower.

Conclusions

These findings suggest that EDF and EDB play important, yet distinct, roles in energy intake and BMI. Future studies should evaluate both types of energy density as independent predictors since our results suggest that EDB can confound the association of EDF with BMI.

Low-carbohydrate (low & high-fat) versus high-carbohydrate low-fat diets in the treatment of obesity in adolescents

AIM

To compare the impact of low-carbohydrate diets of different fat content to high-carbohydrate low-fat diet on weight and metabolic parameters in obese adolescents.

METHODS

Fifty-five patients aged 12-18 years with a body mass index (BMI) above the 95th percentile were randomly allocated to one of three isoenergetic diet regimens. Anthropometric and metabolic measurements were taken after overnight fast, at baseline, after the 12-week intervention and after nine month of follow-up.

RESULTS

No significant differences were found among the groups in changes in BMI, BMI-percentile, fat percentage, or metabolic markers at the end of the intervention and at the end of follow-up. Insulin level and homeostasis model assessment (HOMA) level decreased significantly at both time points only in the two low carbohydrate diet groups.

CONCLUSION

All diet regimens are associated with a significant reduction in BMI and improvement of some metabolic parameters in obese adolescents. Low-carbohydrate diets apparently have no advantage over high-carbohydrate low-fat diets. The significant drop in insulin level and HOMA in the low carbohydrate diet groups is noteworthy given the increasing frequency of type-2 diabetes as part of metabolic syndrome in children and youth. The impact of low carbohydrate diets in obese and insulin-resistant youth warrants further investigation.

Low-carbohydrate, high-protein diets revisited

PURPOSE OF REVIEW

There has been continued interest in the physiological, nutritional and clinical aspects of low-carbohydrate diets. This review will discuss the effects on appetite regulation, metabolic parameters, body weight and body composition, the role of glycemic index and glycemic load, as well as long-term outcomes.

RECENT FINDINGS

Low-carbohydrate, high-protein diets appear to improve satiety through their actions on measures of adiposity and gut peptides that influence appetite and caloric intake. Specific macronutrients such as low glycemic index carbohydrates and dietary protein impact appetite, calorie intake and metabolic parameters independent of weight loss. Long-term data, however, continue to support that total weight loss among low-carbohydrate dieters is not significantly different from low-fat dieters. The long-term safety of low-carbohydrate, high-protein diets on cardiovascular disease risk remains undetermined.

SUMMARY

Low-carbohydrate, high-protein diets may be an effective choice for weight loss, enhanced satiety and improved metabolic parameters.

Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum

BACKGROUND

Altering the macronutrient composition of the diet influences hunger and satiety. Studies have compared high- and low-protein diets, but there are few data on carbohydrate content and ketosis on motivation to eat and ad libitum intake.

OBJECTIVE

We aimed to compare the hunger, appetite, and weight-loss responses to a high-protein, low-carbohydrate [(LC) ketogenic] and those to a high-protein, medium-carbohydrate [(MC) nonketogenic] diet in obese men feeding ad libitum.

DESIGN

Seventeen obese men were studied in a residential trial; food was provided daily. Subjects were offered 2 high-protein (30% of energy) ad libitum diets, each for a 4-wk period-an LC (4% carbohydrate) ketogenic diet and an MC (35% carbohydrate) diet-randomized in a crossover design. Body weight was measured daily, and ketosis was monitored by analysis of plasma and urine samples. Hunger was assessed by using a computerized visual analogue system.

RESULTS

Ad libitum energy intakes were lower with the LC diet than with the MC diet [P=0.02; SE of the difference (SED): 0.27] at 7.25 and 7.95 MJ/d, respectively. Over the 4-wk period, hunger was significantly lower (P=0.014; SED: 1.76) and weight loss was significantly greater (P=0.006; SED: 0.62) with the LC diet (6.34 kg) than with the MC diet (4.35 kg). The LC diet induced ketosis with mean 3-hydroxybutyrate concentrations of 1.52 mmol/L in plasma (P=0.036 from baseline; SED: 0.62) and 2.99 mmol/L in urine (P<0.001 from baseline; SED: 0.36).

CONCLUSION

In the short term, high-protein, low-carbohydrate ketogenic diets reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.

Obesity management

Because obesity is associated with an increased risk of multiple health problems, it is important for gastroenterologists and all health care providers routinely to identify, evaluate, and treat patients for obesity in the course of daily practice. Therapy for obesity always begins with lifestyle management and may include pharmacotherapy or surgery. Setting an initial weight loss goal of 10% over 6 months is a realistic target, followed by long-term management.