Should we recommend low-fat diets for obesity?

The Effectiveness of Nutritional Strategies in the Treatment and Management of Obesity: A Systematic Review

Obesity, a condition primarily resulting from positive energy balance, has become a significant global health concern. Numerous studies have demonstrated that obesity is a major risk factor for various illnesses, including different types of cancer, coronary heart disease, sleep apnea, CV stroke, type II diabetes mellitus, etc. To effectively address this issue, prevention and treatment approaches to manage body weight are crucial. There are several evidence-based approaches available for the treatment and management of obesity, taking into account factors such as body mass index classification, individual weight history, and existing comorbidities. To facilitate successful obesity treatment and management, there are pragmatic approaches and tools available, including the reduction of energy density, portion control, and diet quality enhancement. These approaches encompass the use of medications, lifestyle interventions, bariatric surgery, and formula diets. Regardless of the specific method employed, behavior change, reduction of energy intake, and increased energy expenditure are integral components for successful treatment and management of obesity. These measures allow patients to personalize and customize their dietary patterns, leading to effective and sustainable weight reduction. Incorporating physical activities and self-monitoring of individual diets are effective techniques for promoting behavior change in obesity and weight management. The main objective of this systematic review is to evaluate the effectiveness of dietary/nutritional interventions in the treatment and management of obesity through provision of valuable insights into the effectiveness of such nutritional strategies. To attain this, a comprehensive analysis of various dietary approaches and their impacts on weight will be conducted.

Dietary Strategies for Metabolic Syndrome: A Comprehensive Review

Metabolic syndrome is a cluster of metabolic risk factors, characterized by abdominal obesity, dyslipidemia, low levels of high-density lipoprotein cholesterol (HDL-c), hypertension, and insulin resistance. Lifestyle modifications, especially dietary habits, are the main therapeutic strategy for the treatment and management of metabolic syndrome, but the most effective dietary pattern for its management has not been established. Specific dietary modifications, such as improving the quality of the foods or changing macronutrient distribution, showed beneficial effects on metabolic syndrome conditions and individual parameters. On comparing low-fat and restricted diets, the scientific evidence supports the use of the Mediterranean Dietary Approaches to Stop Hypertension (DASH) diet intervention as the new paradigm for metabolic syndrome prevention and treatment. The nutritional distribution and quality of these healthy diets allows health professionals to provide easy-to-follow dietary advice without the need for restricted diets. Nonetheless, energy-restricted dietary patterns and improvements in physical activity are crucial to improve the metabolic disturbances observed in metabolic syndrome patients.

Obesity and adiposity: the culprit of dietary protein efficacy

Obesity and increased body adiposity have been alarmingly increasing over the past decades and have been linked to a rise in food intake. Many dietary restrictive approaches aiming at reducing weight have resulted in contradictory results. Additionally, some policies to reduce sugar or fat intake were not able to decrease the surge of obesity. This suggests that food intake is controlled by a physiological mechanism and that any behavioural change only leads to a short-term success. Several hypotheses have been postulated, and many of them have been rejected due to some limitations and exceptions. The present review aims at presenting a new theory behind the regulation of energy intake, therefore providing an eye-opening field for energy balance and a potential strategy for obesity management.

Effects of Diets on Adipose Tissue

BACKGROUND

Obesity is a major health problem that has become a global epidemic. Overweight and obesity are commonly associated with the development of several pathologies, such as insulin resistance, cardiovascular diseases, sleep apnea and several types of cancer, which can lead to further morbidity and mortality. An increased abdominal adiposity renders overweight and obese individuals more prone to metabolic and cardiovascular problems.

OBJECTIVE

This Review aims to describe the dietary strategies to deal with excess adiposity given the medical, social and economic consequences of obesity.

METHODS

One hundred and eighty-five papers were included in the present Review.

RESULTS

Excess adiposity leads to several changes in the biology, morphology and function of the adipose tissue, such as adipocyte hypertrophy and hyperplasia, adipose tissue inflammation and fibrosis and an impaired secretion of adipokines, contributing to the onset of obesity- related comorbidities. The first approach for obesity management and prevention is the implementation of a diet combined with physical activity. The present review summarizes the compelling evidence showing body composition changes, impact on cardiometabolism and potential adverse effects of very-low calorie, low- and high-carbohydrate, high-protein or low-fat diets. The use of macronutrients during the preprandial and postprandial state has been also reviewed to better understand the metabolic changes induced by different dietary interventions.

CONCLUSION

Dietary changes should be individualised, tailored to food preferences and allow for flexible approaches to reducing calorie intake in order to increase the motivation and compliance of overweight and obese patients.

Nutritional Challenges in Metabolic Syndrome

Metabolic Syndrome (MetS) is a combination of risk factors for the development of cardiovascular disease (CVD) and type 2 diabetes. Different diagnostic criteria were proposed, but a consensus was reached in 2009 based on values of waist circumference, blood pressure, fasting glycemia, triglycerides, and high-density lipoprotein (HDL)-cholesterol levels. The main underlying etiologic factor is insulin resistance. The quality and quantity of individual macronutrients have an influence on the development and resolution of this syndrome. However, the main treatment goal is weight loss and a decrease in insulin resistance. A controlled energy dietary recommendation, together with moderate levels of physical activity, may positively change the parameters of MetS. However, there is no single dietary or exercise prescription that works for all patients. Dietary patterns such as Mediterranean-style, dietary approaches to stop hypertension (DASH), low-carbohydrate, and low-fat diets can ameliorate insulin resistance and MetS. Long-term adherence to a healthy lifestyle is key in assuring that individuals significantly reduce the risk of CVD and diabetes mellitus.

Environmental risk factors and nonpharmacological and nonsurgical interventions for obesity: An umbrella review of meta-analyses of cohort studies and randomized controlled trials

BACKGROUND

Multiple environmental factors have been implicated in obesity, and multiple interventions, besides drugs and surgery, have been assessed in obese patients. Results are scattered across many studies and meta-analyses, and they often mix obese and overweight individuals.

MATERIALS AND METHODS

PubMed and Cochrane Database of Systematic Reviews were searched through 21 January 2017 for meta-analyses of cohort studies assessing environmental risk factors for obesity, and randomized controlled trials investigating nonpharmacological and nonsurgical therapeutic interventions for obesity. We excluded data on overweight participants. Evidence from observational studies was graded according to criteria that included the statistical significance of the random-effects summary estimate and of the largest study in a meta-analysis, the number of obesity cases, heterogeneity between studies, 95% prediction intervals, small-study effects and excess significance. The evidence of intervention studies for obesity was assessed with the GRADE framework.

RESULTS

Fifty-four articles met eligibility criteria, including 26 meta-analyses of environmental risk factors (166 studies) and 46 meta-analyses of nondrug, nonsurgical interventions (206 trials). In adults, the only risk factor with convincing evidence was depression, and childhood obesity, adolescent obesity, childhood abuse and short sleep duration had highly suggestive evidence. Infancy weight gain during the first year of life, depression and low maternal education had convincing evidence for association with paediatric obesity. All interventions had low or very-low-quality evidence with one exception of moderate-quality evidence for one comparison (no differences in efficacy between brief lifestyle primary care interventions and other interventions for paediatric obesity). Summary effect sizes were mostly small across compared interventions (maximum 5.1 kg in adults and 1.78 kg in children) and even these estimates may be inflated.

CONCLUSIONS

Depression, obesity in earlier age groups, short sleep duration, childhood abuse and low maternal education have the strongest support among proposed risk factors for obesity. Furthermore, there is no high-quality evidence to recommend treating obesity with a specific nonpharmacological and nonsurgical intervention among many available, and whatever benefits in terms of magnitude of weight loss appear small.

ISSN exercise & sports nutrition review update: research & recommendations

Background

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words ‘sport nutrition’. Consequently, staying current with the relevant literature is often difficult.

Methods

This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches.

Conclusions

This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.

The Science of Obesity Management: An Endocrine Society Scientific Statement

The prevalence of obesity, measured by body mass index, has risen to unacceptable levels in both men and women in the United States and worldwide with resultant hazardous health implications. Genetic, environmental, and behavioral factors influence the development of obesity, and both the general public and health professionals stigmatize those who suffer from the disease. Obesity is associated with and contributes to a shortened life span, type 2 diabetes mellitus, cardiovascular disease, some cancers, kidney disease, obstructive sleep apnea, gout, osteoarthritis, and hepatobiliary disease, among others. Weight loss reduces all of these diseases in a dose-related manner-the more weight lost, the better the outcome. The phenotype of "medically healthy obesity" appears to be a transient state that progresses over time to an unhealthy phenotype, especially in children and adolescents. Weight loss is best achieved by reducing energy intake and increasing energy expenditure. Programs that are effective for weight loss include peer-reviewed and approved lifestyle modification programs, diets, commercial weight-loss programs, exercise programs, medications, and surgery. Over-the-counter herbal preparations that some patients use to treat obesity have limited, if any, data documenting their efficacy or safety, and there are few regulatory requirements. Weight regain is expected in all patients, especially when treatment is discontinued. When making treatment decisions, clinicians should consider body fat distribution and individual health risks in addition to body mass index.

Dietary therapy in heart failure with preserved ejection fraction and/or left ventricular diastolic dysfunction in patients with metabolic syndrome

BACKGROUND

Heart failure is an ongoing epidemic of left ventricular (LV) dilatation and/or dysfunction due to the increasing prevalence of predisposing risk factors such as age, physical inactivity, (abdominal) obesity, and type-2-diabetes. Approximately half of these patients have diastolic heart failure (HFpEF). The prognosis of HFpEF is comparable to that of systolic heart failure, but without any known effective treatment.

DIASTOLIC DYSFUNCTION

A biomathematically corrected diagnostic approach is presented that quantifies diastolic dysfunction via the predominant age dependency of LV diastolic function and unmasks (metabolic) risk factors, that are independent of age and, therefore, potential targets for therapy. Patients with HFpEF have reduced cardiac energy reserve that is frequently caused by insulin resistance. Consequently, HFpEF and/or LV diastolic dysfunction may be regarded as a cardiac manifestation of the metabolic syndrome (MetS).

DIETARY THERAPY

Accordingly, a causal therapy for metabolically induced dysfunction aims at normalizing insulin sensitivity by improving postprandial glucose and lipid metabolism. The respective treatments include 1) weight loss induced by dietary energy restriction that is often not sustained long-term and 2) independent of weight loss, focus on carbohydrate modification in exchange for an increase in protein and fat, ideally combined with an aerobic exercise program. Hence, beneficial effects of different macronutrient compositions in the dietary therapy of the underlying MetS are discussed together with the most recently available publications and meta-analyses.

CONCLUSION

Modulation/restriction of carbohydrate intake normalizes postprandial hyperglycemic and insulinemic peaks and has been shown to improve all manifestations of the MetS and also to reduce cardiovascular risk.

Cardiometabolic Syndrome and Increased Risk of Heart Failure

Approximately 50 % of patients with heart failure have diastolic heart failure (HFPEF) with the major predisposing risk factors age, inactivity, obesity, insulin resistance (IR), type-2 diabetes, and hypertension. The prognosis of HFPEF is comparable to that of systolic heart failure, but without any specific or effective treatment. This review presents a biomathematically corrected diagnostic approach for quantification of diastolic dysfunction (DD) via the age dependency of diastolic function. Pathophysiological mechanisms for DD in the cardiometabolic syndrome (CMS) are mainly based on downstream effects of IR including insufficient myocardial energy supply. The second section discusses therapeutic strategies for the control and therapy of CMS, IR, and the associated DD/HFPEF with a focus on dietary therapy that is independent of weight loss but improves all manifestations of the CMS and reduces cardiovascular risk.

Need for Weight Management among Postmenopausal Early Breast Cancer Patients Receiving Adjuvant Endocrine Therapy

Increasingly effective adjuvant therapies mean that the prognosis for postmenopausal women with breast cancer has never been better. Weight problems are common among breast cancer patients and worsen due to the impact of diagnosis and treatment. Recent studies have linked excess weight with the risk of recurrence of breast cancer among premenopausal women. While general obesity (body mass index) does not appear to influence the already much improved prognosis for postmenopausal women, there is some evidence that limiting central obesity and improving insulin resistance may improve survival. The focus of attention for postmenopausal breast cancer survivors is also shifting to consider the mortality and morbidity from other weight-related cancers and noncancer causes, such as cardiovascular disease, making weight control a potentially important adjunct to endocrine therapy. This paper outlines the rationale and optimal design for effective weight management strategies among postmenopausal breast cancer patients receiving endocrine therapy.

The Role of Macronutrient Content in the Diet for Weight Management

Diets to treat obesity have been in existence since Hippocrates treated obesity some 2500 years ago. There are currently a wide variety of diets and a common misconception that a single magical diet can cure overweight and obesity. Systematic reviews and meta-analyses indicate that all diets work when adhered to and that initial weight loss can predict the amount of weight lost and maintained for up to 4 years. Individual preferences are thus key in selecting a diet. There are emerging data pinpointing genetic variability in the metabolic responses to variation in macronutrient intake.

Impact of a male-only weight loss maintenance programme on social-cognitive determinants of physical activity and healthy eating: A randomized controlled trial

OBJECTIVES

To examine the effect of a gender-tailored, Social Cognitive Theory (SCT)-based weight loss maintenance (WLM) intervention on men's physical activity and healthy eating cognitions and behaviours in the 12 months after completing a weight loss programme.

DESIGN

A two-phase, assessor-blinded, randomized controlled trial.

METHODS

Ninety-two overweight/obese men (mean [SD] age: 49.2 years [10.1], BMI: 30.7 [3.3] kg/m(2) ) who lost at least 4 kg after completing the 3-month SCT-based SHED-IT Weight Loss Program were randomly allocated to receive (1) the SCT-based SHED-IT WLM Program; or (2) no additional resources (self-help control group). The 6-month gender-tailored SHED-IT WLM Program was completely self-administered and operationalized SCT behaviour change principles to assist men to increase moderate-to-vigorous physical activity (MVPA) and decrease energy-dense, nutrient-poor (discretionary) food consumption after initial weight loss. After randomization (WLM baseline), men were reassessed at 6 months (WLM post-test) and 12 months (6-month WLM follow-up). SCT cognitions (e.g., self-efficacy, goal setting), MVPA, and discretionary food consumption were assessed with validated measures.

RESULTS

Following significant improvements in cognitions, MVPA and discretionary food consumption during the weight loss phase, intention-to-treat, linear mixed models revealed no significant group-by-time differences in cognitions or behaviours during the WLM phase. Initial improvements in MVPA and some cognitions (e.g., goal setting, planning, and social support) were largely maintained by both groups at the end of the study. Dietary effects were not as strongly maintained, with the intervention and control groups maintaining 57% and 75% of the Phase I improvements in discretionary food intake, respectively.

CONCLUSIONS

An additional SCT-based WLM programme did not elicit further improvements over a self-help control in the cognitions or behaviours for MVPA or discretionary food intake of men who had lost weight with a SCT-based weight loss programme. Statement of contribution What is already known on this subject?Weight regain after weight loss (WL) is common. As successful weight loss maintenance (WLM) requires sustained improvements in cognitions and behaviours, health psychology can contribute to intervention development. However, little research has examined the utility of psychological theory in the context of a WLM randomised controlled trial. What does this study add? A theory-based WL program improved men's physical activity and dietary behaviours and cognitions. Men who also received a theory-based WLM program did not show further improvements in physical activity or dietary cognitions and behaviours compared to those that did not.

The SHED-IT weight loss maintenance trial protocol: A randomised controlled trial of a weight loss maintenance program for overweight and obese men

Despite short-term efficacy, many weight loss studies demonstrate poor long-term results and have difficulty recruiting men. Cost-effective treatments that help men achieve long-term weight loss are required. Using a two-phase, assessor-blinded, parallel-group randomised controlled trial design this study will test the effectiveness and cost-effectiveness of a male-only weight loss maintenance intervention. In Phase I (3 months) 209 men received the SHED-IT Weight Loss Program. In Phase II (12 months) 92 men who lost 4 kg or more were randomised to either (i) a maintenance group who received the 6-month, gender-tailored SHED-IT Weight Loss Maintenance Program, which included no face-to-face contact (n = 47), or (ii) a self-help control group (n = 45). Randomisation was stratified by weight loss (4 kg-7.4 kg, ≥7.5 kg) and BMI (<30 kg/m(2), ≥30 kg/m(2)). Assessments occurred at 'study entry' (start of Phase I), 'baseline' (start of Phase II), '6 months' (post-test) and will occur at '12 months' (follow-up; primary endpoint). The primary outcome is weight change in Phase II (i.e. from 'baseline' at 12 months after randomization). Secondary outcomes include waist circumference (umbilicus and narrowest), blood pressure, body composition, objectively measured physical activity, sedentary time, portion size, dietary intake, quality of life, depressive symptoms, and behavioural cognitions. Costing data will be collected for cost-effectiveness analysis. Generalised linear mixed models (intention-to-treat) will assess outcomes for treatment (maintenance vs. control), time (baseline, 6-month and 12-month) and the treatment-by-time interaction. This will be the first study to evaluate a male-only, gender-targeted weight loss maintenance program. Results will provide evidence regarding feasible and theoretically-driven obesity treatments for men with potential for long-term impact and widespread dissemination.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12612000749808).

Association between self-reported sleep duration and dietary quality in European adolescents

Evidence has grown supporting the role for short sleep duration as an independent risk factor for weight gain and obesity. The purpose of the present study was to examine the relationship between sleep duration and dietary quality in European adolescents. The sample consisted of 1522 adolescents (aged 12.5-17.5 years) participating in the European multi-centre cross-sectional ‘Healthy Lifestyle in Europe by Nutrition in Adolescence’ study. Sleep duration was estimated by a self-reported questionnaire. Dietary intake was assessed by two 24 h recalls. The Diet Quality Index for Adolescents with Meal index (DQI-AM) was used to calculate overall dietary quality, considering the components dietary equilibrium, dietary diversity, dietary quality and a meal index. An average sleep duration of ≥ 9 h was classified as optimal, between 8 and 9 h as borderline insufficient and < 8 h as insufficient. Sleep duration and the DQI-AM score were positively associated (β = 0.027, r 0.130, P< 0.001). Adolescents with insufficient (62.05 (sd 14.18)) and borderline insufficient sleep (64.25 (sd 12.87)) scored lower on the DQI-AM than adolescents with an optimal sleep duration (64.57 (sd 12.39)) (P< 0.001; P= 0.018). The present study demonstrated in European adolescents that short sleep duration was associated with a lower dietary quality. This supports the hypothesis that the health consequences of insufficient sleep may be mediated by the relationship of insufficient sleep to poor dietary quality.

Dietary factors impact on the association between CTSS variants and obesity related traits

Background/Aims

Cathepsin S, a protein coded by the CTSS gene, is implicated in adipose tissue biology–this protein enhances adipose tissue development. Our hypothesis is that common variants in CTSS play a role in body weight regulation and in the development of obesity and that these effects are influenced by dietary factors–increased by high protein, glycemic index and energy diets.

Methods

Four tag SNPs (rs7511673, rs11576175, rs10888390 and rs1136774) were selected to capture all common variation in the CTSS region. Association between these four SNPs and several adiposity measurements (BMI, waist circumference, waist for given BMI and being a weight gainer–experiencing the greatest degree of unexplained annual weight gain during follow-up or not) given, where applicable, both as baseline values and gain during the study period (6–8 years) were tested in 11,091 European individuals (linear or logistic regression models). We also examined the interaction between the CTSS variants and dietary factors–energy density, protein content (in grams or in % of total energy intake) and glycemic index–on these four adiposity phenotypes.

Results

We found several associations between CTSS polymorphisms and anthropometric traits including baseline BMI (rs11576175 (SNP N°2), p = 0.02, β = −0.2446), and waist change over time (rs7511673 (SNP N°1), p = 0.01, β = −0.0433 and rs10888390 (SNP N°3), p = 0.04, β = −0.0342). In interaction with the percentage of proteins contained in the diet, rs11576175 (SNP N°2) was also associated with the risk of being a weight gainer (p_interaction = 0.01, OR = 1.0526)–the risk of being a weight gainer increased with the percentage of proteins contained in the diet.

Conclusion

CTSS variants seem to be nominally associated to obesity related traits and this association may be modified by dietary protein intake.

Weight maintenance through behaviour modification with a cooking course or neurolinguistic programming

We compared the effect on weight regain of behaviour modification consisting of either a gourmet cooking course or neurolinguistic programming (NLP) therapy. Fifty-six overweight and obese subjects participated. The first step was a 12-week weight loss program. Participants achieving at least 8% weight loss were randomized to five months of either NLP therapy or a course in gourmet cooking. Follow-up occurred after two and three years. Forty-nine participants lost at least 8% of their initial body weight and were randomized to the next step. The NLP group lost an additional 1.8 kg and the cooking group lost 0.2 kg during the five months of weight maintenance (NS). The dropout rate in the cooking group was 4%, compared with 26% in the NLP group (p=0.04). There was no difference in weight maintenance after two and three years of follow-up. In conclusion, weight loss in overweight and obese participants was maintained equally efficiently with a healthy cooking course or NLP therapy, but the dropout rate was lower during the active cooking treatment.

Usefulness of combining intermittent hypoxia and physical exercise in the treatment of obesity

Obesity is an important public health problem worldwide and is a major risk factor for a number of chronic diseases such as type II diabetes, adverse cardiovascular events and metabolic syndrome-related features. Different treatments have been applied to tackle body fat accumulation and its associated clinical manifestations. Often, relevant weight loss is achieved during the first 6 months under different dietary treatments. From this point, a plateau is reached, and a gradual recovery of the lost weight may occur. Therefore, new research approaches are being investigated to assure weight maintenance. Pioneering investigations have reported that oxygen variations in organic systems may produce changes in body composition. Possible applications of intermittent hypoxia to promote health and in various pathophysiological states have been reported. The hypoxic stimulus in addition to diet and exercise can be an interesting approach to lose weight, by inducing higher basal noradrenalin levels and other metabolic changes whose mechanisms are still unclear. Indeed, hypoxic situations increase the diameter of arterioles, produce peripheral vasodilatation and decrease arterial blood pressure. Furthermore, hypoxic training increases the activity of glycolytic enzymes, enhancing the number of mitochondria and glucose transporter GLUT-4 levels as well as improving insulin sensitivity. Moreover, hypoxia increases blood serotonin and decreases leptin levels while appetite is suppressed. These observations allow consideration of the hypothesis that intermittent hypoxia induces fat loss and may ameliorate cardiovascular health, which might be of interest for the treatment of obesity. This new strategy may be useful and practical for clinical applications in obese patients.

Risk factors for adult overweight and obesity: the importance of looking beyond the 'big two'

OBJECTIVE

To compare two traditional (high dietary lipid intake and non-participation in high-intensity physical exercise, namely the 'Big Two' factors) versus three nontraditional (short sleep duration, high disinhibition eating behavior, and low dietary calcium intake) risk factors as predictors of excess body weight and overweight/obesity development.

METHOD

Adult participants aged 18-64 years of the Quebec Family Study were selected for cross-sectional (n = 537) and longitudinal (n = 283; 6-year follow-up period) analyses. The main outcome measure was overweight/obesity, defined as a BMI ≥ 25 kg/m(2).

RESULTS

We observed that both the prevalence and incidence of overweight/obesity was best predicted by a combination of risk factors. However, short sleep duration, high disinhibition eating behavior and low dietary calcium intake seemed to contribute more to the risk of overweight and obesity than high dietary lipid intake and non-participation in high-intensity physical exercise. Globally, the risk of being overweight or obese was two-fold higher for individuals having the three nontraditional risk factors combined (OR 6.05; 95% CI 4.26-7.88) compared to those reporting a high percentage of lipids in their diet together with no vigorous physical activity in their daily schedule (OR 2.95; 95% CI 2.18-3.73). Furthermore, the risk of overweight/obesity was also higher for the combination of any two of the nontraditional risk factors than for the combination of the 'Big Two' factors.

CONCLUSION

These results are concordant with previous reports showing that obesity is a multifactorial condition, and emphasize the importance of looking beyond reported measures of the 'Big Two' factors.

Short term effects of energy restriction and dietary fat sub-type on weight loss and disease risk factors

BACKGROUND AND AIMS

Decreasing energy intake relative to energy expenditure is the indisputable tenet of weight loss. In addition to caloric restriction modification of the type of dietary fat may provide further benefits. The aim of the present study was to examine the effect of energy restriction alone and with dietary fat modification on weight loss and adiposity, as well as on risk factors for obesity related disease.

METHODS AND RESULTS

One-hundred and fifty overweight men and women were randomized into a 3month controlled trial with four low fat (30% energy) dietary arms: (1) isocaloric (LF); (2) isocaloric with 10% polyunsaturated fatty acids (LF-PUFA); (3) low calorie (LF-LC) (-2MJ); (4) low calorie with 10% PUFA (LF-PUFA-LC). Primary outcomes were changes in body weight and body fat and secondary outcomes were changes in fasting levels of leptin, insulin, glucose, lipids and erythrocyte fatty acids. Changes in dietary intake were assessed using 3day food records. One-hundred and twenty-two participants entered the study and 95 completed the study. All groups lost weight and body fat (P<0.0001 time effect for both), but the LC groups lost more weight (P=0.026 for diet effect). All groups reduced total cholesterol levels (P<0.0001 time effect and P=0.017 intervention effect), but the LC and PUFA groups were better at reducing triacylglycerol levels (P=0.056 diet effect). HDL increased with LF-LC and LF-PUFA but not with LF-PUFA-LC (0.042 diet effect). The LF and LF-LC groups reported greater dietary fat reductions than the two PUFA groups (P=0.043).

CONCLUSION

Energy restriction has the most potent effect on weight loss and lipids, but fat modification is also beneficial when energy restriction is more modest.

Metabolic syndrome prevalence, dietary intake, and cardiovascular risk profile among overweight and obese adults 18-50 years old from the United Arab Emirates

BACKGROUND

The prevalence of diabetes mellitus is among the highest worldwide, and metabolic syndrome predisposes to diabetes.

METHODS

We recruited 227 overweight/obese Emirati adults living in the city of Al-Ain, Emirati of Abu Dhabi to screen for the metabolic syndrome and to assess for the most relevant criteria for the metabolic syndrome in this population. We identified subjects as having the metabolic syndrome if they had three of the following characteristics: Waist circumference (WC) >88 cm in women and >102 cm in men; plasma glucose >5.5 mmol/L; blood pressure >130/85 mmHg, triglycerides (TG) >1.7 mmol/L, and high-density lipoprotein cholesterol (HDL-C) <1.0 mmol/L in men and <1.3 mmol/L in women. In addition to features of metabolic syndrome, lipoprotein subfractions and 24-hour dietary recalls were assessed in a random sample of participants.

RESULTS

A total of 92 subjects (40.5%) were classified as having metabolic syndrome. The most relevant clinical criteria associated with metabolic syndrome were large WC, high blood pressure, and low HDL-C. Only 7% of subjects had TG >1.7 mmol/L, whereas 95% had plasma LDL-C >2.6 mmol/L. In addition, subjects presented low concentrations of medium very-low-density lipoprotein (VLDL) and small HDL subfractions in agreement with low concentrations of HDL-C and TG. Dietary analysis revealed high-energy consumption, with diets high in total carbohydrates, fat, and simple sugars. In addition, subjects were sedentary with only 14% of the population engaged in physical activity.

CONCLUSIONS

The high prevalence of metabolic syndrome among overweight/obese Emirati adults predisposes this population to increased risk for developing diabetes and cardiovascular disease. Public health involvement targeting poor dietary habits and exercise programs among Emirati citizens is urgently needed.

No evidence of differential effects of SFA, MUFA or PUFA on post-ingestive satiety and energy intake: a randomised trial of fatty acid saturation

BACKGROUND

High fat diets have long been associated with weight gain and obesity, and the weak satiety response elicited in response to dietary lipids is likely to play a role. Suppression of appetite and food intake has consistently been shown to be diminished with high fat relative to either high protein or carbohydrate meals. There is however some evidence that the satiating capacity of lipids may be modulated when physicochemical properties are altered, but studies investigating the effect of lipid saturation on appetite have generated inconsistent findings. This study investigated the effects of changes in fatty acid saturation on post-ingestive satiety and energy intake.

METHODS

High-fat (HF) test breakfasts (2.0 MJ) containing 26 g lipid were given to 18 healthy, lean men in a 3 treatment randomised cross-over design, each treatment separated by a washout of at least 3 days. The breakfasts were high in saturated (SFA, 65% of total fat), polyunsaturated (PUFA, 76%) or monounsaturated (MUFA, 76%) fatty acids, and comprised 2 savoury muffins. Participants rated appetite sensations using visual analogue scales (VAS) to assess palatability immediately following the meals, and hunger and fullness prior to the HF breakfast and throughout the day. Energy intake was measured by covert weighing of a lunch meal which was served 3.5 h after the breakfast, and from which the participants ate ad libitum.

RESULTS

There was no difference in VAS ratings of pleasantness, visual appearance, smell, taste, aftertaste and overall palatability between the 3 high-fat test breakfasts. However, there was also no differential effect of the 3 treatments on ratings of hunger, fullness, satisfaction or prospective food consumption during the 3.5 h following the breakfast meal and over the full 6 h experiment. Energy and macronutrient intake at lunch also did not differ between treatments (mean, sem; SFA: 5275.9 +/- 286.5 kJ; PUFA: 5227.7 +/- 403.9 kJ; MUFA: 5215.6 +/- 329.5 kJ; P > 0.05). The maximum difference in energy intake between treatments was less than 2%.

CONCLUSIONS

There was no evidence of a difference in post-ingestion satiety between high fat meals which differed in saturation profile in this group of lean, healthy men.

Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes: a fresh look at the evidence

Dietary and policy recommendations frequently focus on reducing saturated fatty acid consumption for improving cardiometabolic health, based largely on ecologic and animal studies. Recent advances in nutritional science now allow assessment of critical questions about health effects of saturated fatty acids (SFA). We reviewed the evidence from randomized controlled trials (RCTs) of lipid and non-lipid risk factors, prospective cohort studies of disease endpoints, and RCTs of disease endpoints for cardiometabolic effects of SFA consumption in humans, including whether effects vary depending on specific SFA chain-length; on the replacement nutrient; or on disease outcomes evaluated. Compared with carbohydrate, the TC:HDL-C ratio is nonsignificantly affected by consumption of myristic or palmitic acid, is nonsignificantly decreased by stearic acid, and is significantly decreased by lauric acid. However, insufficient evidence exists for different chain-length-specific effects on other risk pathways or, more importantly, disease endpoints. Based on consistent evidence from human studies, replacing SFA with polyunsaturated fat modestly lowers coronary heart disease risk, with ~10% risk reduction for a 5% energy substitution; whereas replacing SFA with carbohydrate has no benefit and replacing SFA with monounsaturated fat has uncertain effects. Evidence for the effects of SFA consumption on vascular function, insulin resistance, diabetes, and stroke is mixed, with many studies showing no clear effects, highlighting a need for further investigation of these endpoints. Public health emphasis on reducing SFA consumption without considering the replacement nutrient or, more importantly, the many other food-based risk factors for cardiometabolic disease is unlikely to produce substantial intended benefits.

ISSN exercise & sport nutrition review: research & recommendations

Sports nutrition is a constantly evolving field with hundreds of research papers published annually. For this reason, keeping up to date with the literature is often difficult. This paper is a five year update of the sports nutrition review article published as the lead paper to launch the JISSN in 2004 and presents a well-referenced overview of the current state of the science related to how to optimize training and athletic performance through nutrition. More specifically, this paper provides an overview of: 1.) The definitional category of ergogenic aids and dietary supplements; 2.) How dietary supplements are legally regulated; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of the ergogenic value of nutrition and dietary supplementation in regards to weight gain, weight loss, and performance enhancement. Our hope is that ISSN members and individuals interested in sports nutrition find this review useful in their daily practice and consultation with their clients.

Dietary fat intake and subsequent weight change in adults: results from the European Prospective Investigation into Cancer and Nutrition cohorts

BACKGROUND

It is unclear from the inconsistent epidemiologic evidence whether dietary fat intake is associated with future weight change.

OBJECTIVE

The objective was to assess the association between the amount and type of dietary fat and subsequent weight change (follow-up weight minus baseline weight divided by duration of follow-up).

DESIGN

We analyzed data from 89,432 men and women from 6 cohorts of the EPIC (European Prospective Investigation into Cancer and Nutrition) study. Using country-specific food-frequency questionnaires, we examined the association between baseline fat intake (amount and type of total, saturated, polyunsaturated, and monounsaturated fats) and annual weight change by using the residual, nutrient density, and energy-partition methods. We used random-effects meta-analyses to obtain pooled estimates across centers.

RESULTS

Mean total fat intake as a percentage of energy intake ranged between 31.5% and 36.5% across the 6 cohorts (58% women; mean +/- SD age: 53.2 +/- 8.6 y). The mean (+/-SD) annual weight change was 109 +/- 817 g/y in men and 119 +/- 823 g/y in women. In pooled analyses adjusted for anthropometric, dietary, and lifestyle factors and follow-up period, no significant association was observed between fat intake (amount or type) and weight change. The difference in mean annual weight change was 0.90 g/y (95% CI: -0.54, 2.34 g/y) for men and -1.30 g/y (95% CI: -3.70, 1.11 g/y) for women per 1 g/d energy-adjusted fat intake (residual method).

CONCLUSIONS

We found no significant association between the amount or type of dietary fat and subsequent weight change in this large prospective study. These findings do not support the use of low-fat diets to prevent weight gain.

Risk factors for adult overweight and obesity in the Quebec Family Study: have we been barking up the wrong tree?

The aim of this study was to determine the independent contribution of previously reported risk factors for adult overweight and obesity. A cross-sectional (n=537) and a longitudinal (n=283; 6-year follow-up period) analysis was performed for nine risk factors for overweight and obesity assessed in adult participants (aged 18-64 years) of the Quebec Family Study (QFS). The main outcome measure was overweight/obesity, defined as a BMI>or=25 kg/m2. Using logistic regression analysis adjusted for age, sex, and socioeconomic status, short sleep duration, high disinhibition eating behavior, low dietary calcium intake, high susceptibility to hunger behavior, nonparticipation in high-intensity physical exercise, high dietary restraint behavior, nonconsumption of multivitamin and dietary supplements, high dietary lipid intake, and high alcohol intake were all significantly associated with overweight and obesity in the cross-sectional sample. The analysis of covariance adjusted for age, socioeconomic status, and all other risk factors revealed that only individuals characterized by short sleep duration, high disinhibition eating behavior, and low dietary calcium intake had significantly higher BMI compared to the reference category in both sexes. Over the 6-year follow-up period, short-duration sleepers, low calcium consumers, and those with a high disinhibition and restraint eating behavior score were significantly more likely to gain weight and develop obesity. These results show that excess body weight or weight gain results from a number of obesogenic behaviors that have received considerable attention over the past decade. They also indicate that the four factors, which have the best predictive potential of variations in BMI, be it in a cross-sectional or a longitudinal analytical design, do not have a "caloric value" per se.

Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study

BACKGROUND

Our aim was to compare the effects of a Paleolithic ('Old Stone Age') diet and a diabetes diet as generally recommended on risk factors for cardiovascular disease in patients with type 2 diabetes not treated with insulin.

METHODS

In a randomized cross-over study, 13 patients with type 2 diabetes, 3 women and 10 men, were instructed to eat a Paleolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts; and a Diabetes diet designed in accordance with dietary guidelines during two consecutive 3-month periods. Outcome variables included changes in weight, waist circumference, serum lipids, C-reactive protein, blood pressure, glycated haemoglobin (HbA1c), and areas under the curve for plasma glucose and plasma insulin in the 75 g oral glucose tolerance test. Dietary intake was evaluated by use of 4-day weighed food records.

RESULTS

Study participants had on average a diabetes duration of 9 years, a mean HbA1c of 6,6% units by Mono-S standard and were usually treated with metformin alone (3 subjects) or metformin in combination with a sulfonylurea (3 subjects) or a thiazolidinedione (3 subjects). Mean average dose of metformin was 1031 mg per day. Compared to the diabetes diet, the Paleolithic diet resulted in lower mean values of HbA1c (-0.4% units, p = 0.01), triacylglycerol (-0.4 mmol/L, p = 0.003), diastolic blood pressure (-4 mmHg, p = 0.03), weight (-3 kg, p = 0.01), BMI (-1 kg/m2, p = 0.04) and waist circumference (-4 cm, p = 0.02), and higher mean values of high density lipoprotein cholesterol (+0.08 mmol/L, p = 0.03). The Paleolithic diet was mainly lower in cereals and dairy products, and higher in fruits, vegetables, meat and eggs, as compared with the Diabetes diet. Further, the Paleolithic diet was lower in total energy, energy density, carbohydrate, dietary glycemic load, saturated fatty acids and calcium, and higher in unsaturated fatty acids, dietary cholesterol and several vitamins. Dietary GI was slightly lower in the Paleolithic diet (GI = 50) than in the Diabetic diet (GI = 55).

CONCLUSION

Over a 3-month study period, a Paleolithic diet improved glycemic control and several cardiovascular risk factors compared to a Diabetes diet in patients with type 2 diabetes.

Fat intake and weight development from 9 to 16 years of age: the European youth heart study - a longitudinal study

OBJECTIVE

The literature on associations between fat intake and weight development among both children and adults is inconsistent, even if it is generally assumed that a high dietary fat intake is a major determinant of obesity. The present study aimed at investigating the association between fat intake and weight development among a cohort of children aged 9-10 years at baseline and 15-16 years at follow-up, and, further, at investigating whether parents' obesity is modifying the association.

METHOD

Among 384 subjects aged 9 years, data on dietary intake, BMI z-score, physical activity, inactivity, parents' social status, parents' body mass index, child birth weight, and status of puberty was obtained in 1997. Weight and height was measured both at baseline and at 6-year follow-up, and BMI z-score was calculated. Linear regression was used to assess the role of fat intake on subsequent weight change between 1997 and 2003 with the above-mentioned variables as confounders, in 3 different models and for each sex separately.

RESULTS

The analysis showed no relation between fat intake (both absolute intake and fat energy percent) at 9 years and subsequent 6-year weight change. Only BMI z-score at baseline had a significant relation to weight change for both sexes, and number of obese parents had significant relation to weight change in girls. Number of overweight parents did not modify the association between fat intake and weight change.

CONCLUSION

This study was unable to find a relation between fat intake and 6-year weight change among 9-year-old children. No interaction was seen between number of overweight parents on the relation between fat intake and subsequent weight change.

Comparison of 3 ad libitum diets for weight-loss maintenance, risk of cardiovascular disease, and diabetes: a 6-mo randomized, controlled trial

BACKGROUND

The optimal dietary content and type of fat and carbohydrate for weight management has been debated for decades.

OBJECTIVE

The objective was to compare the effects of 3 ad libitum diets on the maintenance of an initial weight loss of >or=8% and risk factors for CVD and diabetes during a 6-mo controlled dietary intervention.

DESIGN

Nondiabetic overweight or obese [mean +/- SD body mass index (in kg/m(2)): 31.5 +/- 2.6] men (n = 55) and women (n = 76) aged 28.2 +/- 4.8 y were randomly assigned to a diet providing a moderate amount of fat (35-45% of energy) and >20% of fat as monounsaturated fatty acids (MUFA diet; n = 54), to a low-fat (20-30% of energy) diet (LF diet; n = 51), or to a control diet (35% of energy as fat; n = 26). Protein constituted 10-20% of energy in all 3 diets. All foods were provided free of charge from a purpose-built supermarket.

RESULTS

More subjects dropped out of the MUFA (28%) group than out of the LF group (16%) and control group (8%) (MUFA compared with control: P < 0.05). All groups regained weight (MUFA: 2.5 +/- 0.7 kg; LF: 2.2 +/- 0.7 kg; and control: 3.8 +/- 0.8 kg; NS). Body fat regain was lower in the LF (0.6 +/- 0.6%) and MUFA (1.6 +/- 0.6%) groups than in the control group (2.6 +/- 0.5%) (P < 0.05). In the MUFA group, fasting insulin decreased by 2.6 +/- 3.5 pmol/L, the homeostasis model assessment of insulin resistance by 0.17 +/- 0.13, and the ratio of LDL to HDL by 0.33 +/- 0.13; in the LF group, these variables increased by 4.3 +/- 3.0 pmol/L (P < 0.08) and 0.17 +/- 0.10 (P < 0.05) and decreased by 0.02 +/- 0.09 (P = 0.005), respectively; and in the control group, increased by 14.0 +/- 4.3 pmol/L (P < 0.001), 0.57 +/- 0.17 (P < 0.001), and 0.05 +/- 0.14 (P = 0.036), respectively. Dietary adherence was high on the basis of fatty acid changes in adipose tissue.

CONCLUSIONS

Diet composition had no major effect on preventing weight regain. However, both the LF and MUFA diets produced less body fat regain than did the control diet, and the dropout rate was lowest in the LF diet group, whereas fasting insulin decreased and the homeostasis model assessment of insulin resistance and ratio of LDL to HDL improved with the MUFA diet. This trial was registered at clinicaltrials.gov as NCT00274729.

Lifestyle and pharmacological approaches to weight loss: efficacy and safety

CONTEXT

Obesity results from a prolonged small positive energy balance, and its treatment needs to reverse this imbalance.

EVIDENCE ACQUISITION

Citations retrieved from PubMed and The Handbook of Obesity 2008 were selected to illustrate the points.

EVIDENCE SYNTHESIS

Many different diets have been tried to treat obesity, and weight loss occurs with all of them. There is currently no evidence that clearly supports a superiority of one macronutrient composition for diets used for weight loss. The principal effect seems to be the degree of adherence to the prescribed calorie reduction. Lifestyle strategies to modify eating behavior can be used in individual counseling sessions or in groups, both of which are important in helping patients modify their patterns of eating. Physical activity is particularly important in helping patients maintain a weight loss once achieved and is less valuable for weight loss itself. Food intake is controlled through many different mechanisms, but only a few drugs have been developed that tap these mechanisms. Orlistat, which blocks intestinal lipase, is one; sibutramine, a serotonin-norepinephrine reuptake inhibitor, is a second. Surgical approaches provide the most dramatic weight loss and have been demonstrated to reduce long-term mortality and reduce the incidence of diabetes.

CONCLUSIONS

Weight loss can be achieved by many methods, but the surgical procedures appear to be the most durable.

Dietary treatment for obesity

In patients with obesity, low-fat diets seem to result in a weight loss of 3-4 kg at 3 years, but long-term data are limited. Calorie-controlled diets seem to outperform low-fat diets with reported weight losses of 6-7 kg at 4 years, but, again, data are very limited; an initial very-low-calorie diet approach does not lead to greater weight loss than low-fat diets in the long term. Use of meal replacements can lead to an 8 kg weight loss at 4 years, but this finding has been reported only in one, uncontrolled study. High-protein, low-carbohydrate (or very-low-carbohydrate) diets have also been evaluated and seem to be superior to high-carbohydrate diets at least for up to 2 years. Very-low-carbohydrate diets can lead to elevations in LDL cholesterol levels in some individuals. Cognitive behavioral therapy added to diet therapy can facilitate approximately 5 kg additional weight loss, and exercise can facilitate an additional 1-1.5 kg weight loss. Drug treatment, particularly with sibutramine and rimonabant, can increase weight loss with a mildly hypocaloric diet by an additional 3-5 kg, but weight-loss drugs are costly and have adverse effects. If dietary and medical therapies fail, gastric banding can lead to a weight loss of approximately 14% at 10 years, with greater losses of up to 25% with gastric bypass and gastroplasty. Bariatric surgery can also lead to a reduction in mortality and comorbidities but adverse effects can occur including nutritional deficiencies and gastrointestinal symptoms.

Treatment modalities of obesity: what fits whom?

The prevalence of obesity is increasing in both developed and developing countries, with rates reaching approximately 10-35% among adults in the Euro-American region. Obesity is associated with increased risks of cardiovascular diseases, type 2 diabetes, arthritis, and some type of cancers. Obesity significantly affects the quality of life and reduces the average life expectancy. The effective treatment of obesity should address both the medical and the social burden of this disease. Obesity needs to be treated within the health care system as any other complex disease, with empathy and without prejudice. Both health care providers and patients should know that the obesity treatment is a lifelong task. They should also set realistic goals before starting the treatment, whereas keeping in mind that even a modest weight loss of 5-15% significantly reduces obesity-related health risks. Essential treatment of obesity includes low-calorie low-fat diets, increased physical activity, and strategies contributing to the modification of lifestyle. Anti-obesity drugs facilitate weight loss and contribute to further amelioration of obesity-related health risks. A short-term weight loss, up to 6 months, is usually achieved easily. However, the long-term weight management is often associated with a lack of compliance, failures, and a high dropout rate. Regular physical activity, cognitive behavioral modification of lifestyle, and administration of anti-obesity drugs improve weight loss maintenance. Bariatric surgery is an effective strategy to treat severely obese patients. Bariatric surgery leads to a substantial improvement of comorbidities as well as to a reduction in overall mortality by 25-50% during the long-term follow-up. Obesity treatment should be individually tailored and the following factors should be taken into account: sex, the degree of obesity, individual health risks, psychobehavioral and metabolic characteristics, and the outcome of previous weight loss attempts. In the future, an evaluation of hormonal and genetic determinants of weight loss could also contribute to a better choice of individual therapy for a particular obese patient. A multilevel obesity management network of mutually collaborating facilities should be established to provide individually tailored treatment. Centers of excellence in obesity management represented by multidisciplinary teams should provide comprehensive programs for the treatment of obesity derived from evidence-based medicine.

Nutritional strategies in the prevention and treatment of metabolic syndrome

The metabolic syndrome (MetS) is a clustering of metabolic abnormalities that increase the risk of developing atherosclerotic cardiovascular disease and type 2 diabetes. The exact etiology remains unclear, but it is known to be a complex interaction between genetic, metabolic, and environmental factors. Among environmental factors, dietary habits are of central importance in the prevention and treatment of this condition. However, there is currently no firm consensus on the most appropriate dietary recommendations. General recommendations include decreasing obesity, increasing physical activity, and consuming an anti-atherogenic diet, and have traditionally focused on low total fat intake. A major problem with the focus on low fat is that high-carbohydrate diets can contribute to increasing triglyceride and decreasing high-density lipoprotein (HDL) concentrations. Low-carbohydrate diets have been popular in recent years. However, such diets are typically higher in saturated fat and lower in fruits, vegetables, and whole grains than national dietary recommendations. More recently the quality of carbohydrate has been studied in relation to MetS, including a focus on dietary fiber and glycemic index. Similarly, there has been a move from limiting total fat to a focus on the quality of the fat, with evidence of beneficial effects of replacing some carbohydrate with monounsaturated fat. Other nutrients examined for possible importance include calcium, vitamin D, and magnesium. Together, the evidence suggests that the components of diet currently recommended as "healthy" are likely also protective against MetS, including low saturated and trans fat (rather than low total fat) and balanced carbohydrate intake rich in dietary fiber, as well as high fruit and vegetable intake (rather than low total carbohydrate); and the inclusion of low-fat dairy foods. Accelerating research on gene-diet interactions is likely to contribute interesting information that may lead to further individualized dietary guidance in the future.

Dietary fat and weight gain among women in the Nurses' Health Study

OBJECTIVE

To assess the association of dietary fat and weight gain among adult women and to investigate whether offspring of overweight parents have a greater predisposition to weight gain due to intake of dietary fat.

RESEARCH METHODS AND PROCEDURES

This was an 8-year follow-up of 41,518 women in the Nurses' Health Study (NHS), a population-based, prospective cohort. The women were 41 to 68 years of age, free of cardiovascular disease, cancer, and diabetes in 1986 when "baseline" weight and diet were assessed. Eight years later (1994), changes in weight and dietary intake were assessed. Linear regression models were used to relate change in weight to fat intake and change in fat intake, using the percentage of energy from carbohydrate as the comparison, adjusted for age, BMI in 1986, leisure time physical activity, time spent sitting, percent of calories from protein, and change in percentage of calories from protein.

RESULTS

Overall, there was a weak positive association between total fat intake (beta=0.11) and weight gain. Increases in monosaturated and polyunsaturated fat were not associated with weight gain, but increases in animal fat, saturated fat, and trans fat had a positive association with weight change. There was not strong evidence of effect modification by parental weight status (p=0.7 to 0.8 for percentage of calories from total fat, animal fat, and vegetable fat); however, the associations were stronger among the overweight compared with leaner women (p<0.05 for percentage of calories from each type of fat). Among overweight women, for every one percentage increase in percentage of calories from trans fat, women gained an additional 2.3 lb (95% confidence interval, 1.80 to 2.86).

CONCLUSION

Our results show that, overall, percent of calories from fat has only a weak positive association with weight gain; however, percentage of calories from animal, saturated, and trans fat has stronger associations. There was no clear evidence that the diet-weight gain association was stronger among offspring of overweight parents, but dietary fat was associated with greater weight gain among overweight women.

Lifestyle correlates of anthropometric estimates of body adiposity in an Italian middle-aged and elderly population: a covariance analysis

OBJECTIVE

To study the relationship between behavioural factors, body adiposity and muscle mass.

SUBJECTS AND METHODS

A total of 1415 Italian individuals (705 men and 710 women) aged 40-74 years from a population-based survey carried out in the town of Bollate (Milan). Analysis of covariance was used to refine and improve the precision of the comparisons.

RESULTS

Men: Smoking and sedentary behaviour were related to larger waist circumference (WC) and smaller hip circumference (HC). Increased WC was also associated with high-fat diet and moderate-to-heavy drinking (compared to light drinkers). Those more educated (completed high school) were leaner and ex-smokers had higher body mass index (BMI) than non-smokers. Women: BMI was inversely related with education, the more educated having also lower muscle mass. The light drinkers were leaner and moderate-to-heavy drinkers had less muscle mass than abstainers. Moderate-to-heavy drinkers had larger WC than light drinkers. A strong negative trend was found in the relationship between dietary fibre and WC. Overall adiposity (BMI) and, more weakly, HC and peripheral subcutaneous fat increased with more TV watching, whereas BMI lowered, together with WC and muscle mass (as measured by the mid-arm circumference), with more walking/cycling.

CONCLUSIONS

Modifiable habits such as smoking (men) and moderate-to-heavy alcohol drinking are associated with a pattern that is particularly deleterious to health: increased intra-abdominal fat and less muscle mass. Prevention strategies should be simultaneously aimed at promoting physical activities and reducing sedentary behaviours. A low-fat, fibre-rich diet seems to be closely related to a healthy distribution of body fat.

Effects of lifestyle modification in polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrine condition with reproductive and metabolic consequences, including anovulation, infertility and an increased prevalence of diabetes mellitus. Obesity, central obesity and insulin resistance are strongly implicated in its aetiology. Dietary weight loss is recommended as the primary treatment strategy; however, effective means of achieving and maintaining weight loss and reproductive and metabolic improvements are unknown. Lifestyle modification programmes with an emphasis on behavioural management and dietary and exercise interventions have been successful in the general population in reducing the risk of diabetes and the metabolic syndrome, and have had some initial success in improving fertility outcomes in PCOS. However, the literature on effective diet and exercise programmes for PCOS has been sparse, and structured advice for implementing components of lifestyle modification programmes should be assessed in this population.

Diet in the management of weight loss

Obesity is an established risk factor for numerous chronic diseases, and successful treatment will have an important impact on medical resources utilization, health care costs, and patient quality of life. With over 60% of our population being overweight, physicians face a major challenge in assisting patients in the process of weight loss and weight-loss maintenance. Low-calorie diets can lower total body weight by an average of 8% in the short term. These diets are well-tolerated and characterize successful strategies in maintaining significant weight loss over a 5-year period. Very-low-calorie diets produce a more rapid weight loss but should only be used for fewer than 16 weeks because of clinical adverse effects. Diets that are severely restricted in carbohydrates (3%-10% of total energy intake) and do not emphasize a reduction of energy intake may be effective in reducing weight in the short term, but there is no evidence that they are sustainable or innocuous in the long term because their high saturated-fat content may be atherogenic. Fat restriction in a weight-loss regimen is beneficial, but the optimal percentage has yet to be determined. Longitudinal trials are needed to resolve these issues. In this article I discuss the evidence for and pitfalls of various types of weight-loss diets and identify issues that physicians need to address in weight loss and weight-loss maintenance.