Should obese patients be counselled to follow a low‐glycaemic index diet? No

In diabetes research the glycaemic index (GI) of carbohydrates has long been recognized and a low GI is recommended. The same is now often the case in lipid research. Recently, a new debate has arisen around whether a low‐GI diet should also be advocated for appetite‐ and long‐term body weight control. A systematic review was performed of published human intervention studies comparing the effects of high‐ and low‐GI foods or diets on appetite, food intake, energy expenditure and body weight. In a total of 31 short‐term studies (<1 d), low‐GI foods were associated with greater satiety or reduced hunger in 15 studies, whereas reduced satiety or no differences were seen in 16 other studies. Low‐GI foods reduced ad libitum food intake in seven studies, but not in eight other studies. In 20 longer‐term studies (<6 months), a weight loss on a low‐GI diet was seen in four and on a high‐GI diet in two, with no difference recorded in 14. The average weight loss was 1.5 kg on a low‐GI diet and 1.6 kg on a high‐GI diet. To conclude, there is no evidence at present that low‐GI foods are superior to high‐GI foods in regard to long‐term body weight control. However, the ideal long‐term study where ad libitum intake and fluctuations in body weight are permitted, and the diets are similar in all aspects except GI, has not yet been performed.     

Resolved: there is sufficient scientific evidence that decreasing sugar‐sweetened beverage consumption will reduce the prevalence of obesity and obesity‐related diseases

Sugar‐sweetened beverages (SSBs) are the single largest source of added sugar and the top source of energy intake in the U.S. diet. In this review, we evaluate whether there is sufficient scientific evidence that decreasing SSB consumption will reduce the prevalence of obesity and its related diseases. Because prospective cohort studies address dietary determinants of long‐term weight gain and chronic diseases, whereas randomized clinical trials (RCTs) typically evaluate short‐term effects of specific interventions on weight change, both types of evidence are critical in evaluating causality. Findings from well‐powered prospective cohorts have consistently shown a significant association, established temporality and demonstrated a direct dose–response relationship between SSB consumption and long‐term weight gain and risk of type 2 diabetes (T2D). A recently published meta‐analysis of RCTs commissioned by the World Health Organization found that decreased intake of added sugars significantly reduced body weight (0.80 kg, 95% confidence interval [CI] 0.39–1.21; P < 0.001), whereas increased sugar intake led to a comparable weight increase (0.75 kg, 0.30–1.19; P = 0.001). A parallel meta‐analysis of cohort studies also found that higher intake of SSBs among children was associated with 55% (95% CI 32–82%) higher risk of being overweight or obese compared with those with lower intake. Another meta‐analysis of eight prospective cohort studies found that one to two servings per day of SSB intake was associated with a 26% (95% CI 12–41%) greater risk of developing T2D compared with occasional intake (less than one serving per month). Recently, two large RCTs with a high degree of compliance provided convincing data that reducing consumption of SSBs significantly decreases weight gain and adiposity in children and adolescents. Taken together, the evidence that decreasing SSBs will decrease the risk of obesity and related diseases such as T2D is compelling. Several additional issues warrant further discussion. First, prevention of long‐term weight gain through dietary changes such as limiting consumption of SSBs is more important than short‐term weight loss in reducing the prevalence of obesity in the population. This is due to the fact that once an individual becomes obese, it is difficult to lose weight and keep it off. Second, we should consider the totality of evidence rather than selective pieces of evidence (e.g. from short‐term RCTs only). Finally, while recognizing that the evidence of harm on health against SSBs is strong, we should avoid the trap of waiting for absolute proof before allowing public health action to be taken.     

A systematic review of the evidence regarding efficacy of obesity prevention interventions among adults

In the past, interventions aimed at reducing obesity have mainly targeted at weight loss treatment in obese adults, with limited long‐term effects. With the increasing number of people being obese and being at risk for obesity, there has been a shift in focus towards prevention of obesity. We conducted a systematic review of the peer‐reviewed literature on the efficacy of obesity prevention interventions in adults in order to identify effective interventions and intervention elements. Pubmed, OVID, and Web of Science databases were searched from January 1996 to June 2006. Interventions aimed at primary prevention of weight gain among adults achieved by focusing on dietary intake, physical activity or the combination of both were included. The outcome measure had to be difference in change in body mass index or body weight between the intervention and the control groups. Nine studies were included, five long‐term studies (at least 1 year) and four short‐term (3 months to 1 year). Seven studies evaluated an intervention that focused on a combination of diet and physical activity to prevent weight gain, one on diet only and one on physical activity only. One dietary intervention (long‐term), and three combined dietary and physical activity interventions (one long‐term and two short‐term) produced significantly positive results at end of follow‐up. The two long‐term, effective interventions consisted of intensive and long‐term intervention implementation, including groups sessions designed to promote behavioural changes. The current evidence of efficacy of obesity prevention interventions is based on a very small number of studies. Some studies showed a positive impact on body mass index or weight status, but there was too much heterogeneity in terms of study design, theoretical underpinning and target population to draw firm conclusions about which intervention approaches are more effective than others. More research is urgently needed to extend the body of evidence.     

Short- and long-term relationships of serum ghrelin with changes in body composition and the metabolic syndrome in prepubescent obese children following two different weight loss programmes

Objectives Ghrelin has been proposed to be a regulator of energy balance, and its dysregulation may be important in obesity. The aims of this study were (i) to compare short‐ and long‐term changes in circulating ghrelin concentration after increasing energy expenditure vs. its changes after decreasing energy intake, (ii) to determine factors associated with changes in ghrelin level, and (iii) to assess relationships of ghrelin concentration with metabolic syndrome (MetS) in prepubescent obese children. Design Randomized controlled trial. Patients About 100 obese children aged 7–9 years. Measurements After baseline testing, children were randomly assigned to two interventional groups, either receiving dietary recommendations or engaging in physical training classes for 6 months. Ghrelin, insulin, leptin, fasting blood sugar, lipid profile and anthropometric indexes, as well as energy intake and expenditure were measured. Results Of the participants, 92 completed the 6‐month trial, and 87 returned for the 1‐year follow‐up. Except ghrelin level, other biochemical variables had no significant change at 12‐ vs. 6‐month follow‐up. In both groups, ghrelin showed a progressive increase in the periods of time with significant reduction of overweight and negative energy balance; while after the end of the trial, when children regained weight, it decreased toward baseline levels. Baseline ghrelin had strong negative correlation with measures of central obesity. The odds of having the MetS were 12% lower in the middle and 37% lower in the highest tertile of ghrelin level. As the number of MetS components increased, there was a progressive decrease in ghrelin and quantitative insulin sensitivity check index (QUICKI), with a progressive increase in serum insulin, HOMA‐R and leptin levels. Conclusions Ghrelin increases in response to overweight reduction and negative energy balance resulting from either an exercise intervention or reduction in food intake in prepubescent obese children. It is unlikely to regulate long‐term energy balance in young obese children.     

Effects of whey protein supplementation on adiposity,body weight,and glycemic parameters: A synthesis of evidence

AimsThe aim of this review was to analyze the evidence of whey protein supplementation on body weight, fat mass, lean mass and glycemic parameters in subjects with overweight or type 2 diabetes mellitus (T2DM) undergoing calorie restriction or with ad libitum intake.Data synthesisOverweight and obesity are considered risk factors for the development of chronic noncommunicable diseases such as T2DM. Calorie restriction is a dietary therapy that reduces weight and fat mass, promotes the improvement of glycemic parameters, and decreases muscle mass. The maintenance of muscle mass during weight loss is necessary in view of its implication in preventing chronic diseases and improving functional capacity and quality of life. The effects of increased protein consumption on attenuating muscle loss and reducing body fat during calorie restriction or ad libitum intake in overweight individuals are discussed. Some studies have demonstrated the positive effects of whey protein supplementation on improving satiety and postprandial glycemic control in short term; however, it remains unclear whether long-term whey protein supplementation can positively affect glycemic parameters.ConclusionsAlthough whey protein is considered to have a high nutritional quality, its effects in the treatment of overweight, obese individuals and those with T2DM undergoing calorie restriction or ad libitum intake are still inconclusive.     

Running on mixed fuel‐dual agonistic approach of GLP‐1 and GCG receptors leads to beneficial impact on body weight and blood glucose control: A comparative study between mice and non‐human primates

Aim

We performed acute and chronic studies in healthy and diet‐induced obese animals using mouse‐specific or monkey‐specific dual GLP‐1R/GCGR agonists to investigate their effects on food intake, body weight, blood glucose control and insulin secretion. The selective GLP‐1R agonist liraglutide was used as comparator.

Methods

The mouse‐specific dual agonist and liraglutide were tested in lean wild type, GLP‐1R knockout and diet‐induced obese mice at different doses. A chronic study was performed in DIO mice to investigate the effect on body weight, food consumption and total energy expenditure (TEE) in obese and diabetic monkeys with a focus on body weight and energy intake.

Results

The mouse‐specific dual agonist and liraglutide similarly affected glycaemic control. A higher loss in body weight was measured in dual agonist‐treated obese mice. The dual agonist significantly enhanced plasma glucose excursion in overnight fed GLP‐1R^?/? mice, probably reflecting a potent GCGR agonist activity. It increased TEE and enhanced fat and carbohydrate oxidation, while liraglutide produced no effect on TEE. In obese and diabetic monkeys, treatment with the monkey‐specific dual agonist reduced total energy intake to 60%‐70% of baseline TEI during chronic treatment. A decrease in body weight and significant improvement in glucose tolerance was observed.

Conclusions

In DIO mice and non‐human primates, dual agonists elicited robust glycaemic control, similar to the marketed GLP‐1R agonist, while eliciting greater effects on body weight. Results from DIO mice suggest that the increase in TEE is caused not only by increased fat oxidation but also by an increase in carbohydrate oxidation.     

A role for olestra in body weight management

Olestra is a fat substitute made from fatty acids esterified to sucrose and can be used in the preparation of virtually any food made with fat. Foods made with olestra retain the mouthfeel, palatability and satiating effects of their full‐fat counterparts without providing any digestible energy. Because olestra provides no energy, it has the potential to be a useful tool in weight loss and weight maintenance. Short‐term studies of olestra replacement in foods demonstrate that fat replacement leads to a net reduction in fat intake. When excess total energy is available, fat replacement also reduces total energy intake in lean and obese men and women. In longer‐term studies in which olestra is incorporated into the daily diet, there is an incomplete compensation for the fat energy replaced by olestra. When overweight men consumed olestra as part of a varied diet over nine months, weight loss continued for the duration of the study, whereas individuals receiving a typical low‐fat diet regained most of the initial weight lost. Other studies are underway to examine the usefulness of olestra in long‐term weight maintenance following weight loss. Post‐marketing surveillance of olestra foods in the United States indicates that substitution of olestra for only 1–2 g of fat d^?1 may be sufficient to prevent the average weight gain reported in adults of 0.5–1.0 kg year^?1.     

Should we recommend low‐fat diets for obesity?

Dietary fat intake has been blamed for the increase in adiposity and has led to a worldwide effort to decrease the amount of fat in the diet. However, the comparative efficacy of this approach is debatable. Whilst short‐term dietary intervention studies show that low‐fat diets lead to weight loss in both healthy and overweight individuals, it is less clear if a reduction in fat intake is more efficacious than other dietary restrictions in the long term. The purpose of this systematic review was to determine the effectiveness of low‐fat diets in achieving sustained weight loss when used for the express purpose of weight loss in obese or overweight people. A comprehensive search identified six studies that fulfilled our criteria for inclusion (randomized controlled trial, participants either overweight or obese, comparison of a low‐fat diet with another type of weight‐reducing diet, follow‐up period that was at least 6 months in duration and inclusion of participants 18 years or older without serious disease). There were a total of 594 participants in the six trials. The duration of the intervention varied from 3 to 18 months with follow‐up from 6 to 18 months. There were no significant differences between low‐fat diets and other weight‐reducing diets in terms of sustained weight loss. Furthermore, the overall weight loss at the 12–18‐month follow‐up in all studies was very small (2–4 kg). In overweight or obese individuals who are dieting for the purpose of weight reduction, low‐fat diets are as efficacious as other weight‐reducing diets for achieving sustained weight loss, but not more so.     

Long-term effectiveness of diet-plus-exercise interventions vs. diet-only interventions for weight loss: a meta-analysis

Diet and exercise are two of the commonest strategies to reduce weight. Whether a diet‐plus‐exercise intervention is more effective for weight loss than a diet‐only intervention in the long‐term has not been conclusively established. The objective of this study was to systemically review the effect of diet‐plus‐exercise interventions vs. diet‐only interventions on both long‐term and short‐term weight loss. Studies were retrieved by searching MEDLINE and Cochrane Library (1966 – June 2008). Studies were included if they were randomized controlled trials comparing the effect of diet‐plus‐exercise interventions vs. diet‐only interventions on weight loss for a minimum of 6 months among obese or overweight adults. Eighteen studies met our inclusion criteria. Data were independently extracted by two investigators using a standardized protocol. We found that the overall standardized mean differences between diet‐plus‐exercise interventions and diet‐only interventions at the end of follow‐up were ?0.25 (95% confidence interval [CI]?0.36 to ?0.14), with a P‐value for heterogeneity of 0.4. Because there were two outcome measurements, weight (kg) and body mass index (kg m^?2), we also stratified the results by weight and body mass index outcome. The pooled weight loss was 1.14 kg (95% CI 0.21 to 2.07) or 0.50 kg m^?2 (95% CI 0.21 to 0.79) greater for the diet‐plus‐exercise group than the diet‐only group. We did not detect significant heterogeneity in either stratum. Even in studies lasting 2 years or longer, diet‐plus‐exercise interventions provided significantly greater weight loss than diet‐only interventions. In summary, a combined diet‐plus‐exercise programme provided greater long‐term weight loss than a diet‐only programme. However, both diet‐only and diet‐plus‐exercise programmes are associated with partial weight regain, and future studies should explore better strategies to limit weight regain and achieve greater long‐term weight loss.     

Characteristics of diet patterns in metabolically obese, normal weight adults (Korean National Health and Nutrition Examination Survey III, 2005)

Background and aimsMetabolically obese normal weight (MONW) subjects are a subgroup of individuals who have a normal weight and body mass index (BMI), but exhibit obesity-related abnormalities. The objective of this study was to analyze the prevalence of metabolic syndrome (MetS) and characteristics of diet patterns in MONW Koreans.Methods and resultsWe analyzed the data of 3050 adults > 20 years of age with a normal BMI (18.5～24.9 kg/m²) obtained from the Korea National Health and Nutrition Examination Survey III. Anthropometric measurements and information on health behaviors were obtained. The diagnostic criteria for MetS were defined by the International Diabetes Federation consensus. Dietary intake was assessed by the 24-h recall method. The weighted prevalence of MONW was 14.3%. The risk of MONW correlated inversely with the frequency of snacking and positively with the type of snack, particularly those with high carbohydrates.A high carbohydrate diet (≥73.9% of energy intake) compared to a low carbohydrate diet (<59.9% of energy intake) was positively associated with the risk of MONW (OR = 2.54; 95% CI: 1.41, 4.56), whereas a high protein diet (≥17.1% of energy intake) compared to a low protein diet (<12.2% of energy intake) reduced the risk of MONW (OR = 0.60; 95% CI: 0.39, 0.92) in females, but not in males.ConclusionsThis study suggests that a reduced intake of carbohydrates and carbohydrate snacks were associated with a lower prevalence of MONW in females.     

Consumption of sugars and body weight

The role of dietary sugars in the current obesity epidemic is much debated and opposing views can be found in the lay as well as scientific literature. Here we have reviewed the recent scientific literature on consumption of sugars and body weight. Main focus was on three questions: (i) What is the evidence that intake of dietary sugars is associated with higher body weight than intake of non-sugar carbohydrates? (ii) What is the evidence that sugars in liquid form are associated with higher body weight than sugars in solid form? (iii) What is the evidence that diets with a low glycaemic index (GI) or glycaemic load (GL) are associated with lower body weight than diets high in GI or GL? We conclude that (i) there is insufficient evidence that an exchange of sugar for non-sugar carbohydrates in the context of a reduced-fat ad libitum diet or energy-restricted diet results in lower body weights; (ii) observational studies suggest a possible relationship between consumption of sugar-sweetened beverages and body weight, but there is currently insufficient supporting evidence from randomized controlled trials of sufficient size and duration; (iii) at this moment there is insufficient evidence to support a difference between liquid and solid sugar intake in body-weight control and (iv) there is some, although not consistent, evidence for a lower body weight on diets with a lower GL, but the effect is likely to be small. There is currently no convincing evidence for a role of GI independent of GL.     

Whole grain intake in relation to body weight: from epidemiological evidence to clinical trials

This viewpoint aims to 1) review the available scientific literature on the relationship between whole grain consumption and body weight regulation; 2) evaluate the potential mechanisms whereby whole grain intake may help reduce overweight and 3) try to understand why epidemiological studies and clinical trials provide diverging results on this topic. All the prospective epidemiological studies demonstrate that a higher intake of whole grains is associated with lower BMI and body weight gain. However, these results do not clarify whether whole grain consumption is simply a marker of a healthier lifestyle or a factor favoring "per se" lower body weight. Habitual whole grain consumption seems to cause lower body weight by multiple mechanisms such as lower energy density of whole grain based products, lower glycemic index, fermentation of non digestible carbohydrates (satiety signals) and finally by modulating intestinal microflora. In contrast with epidemiological evidence, the results of few clinical trials do not confirm that a whole grain low-calorie diet is more effective in reducing body weight than a refined cereal diet, but their results may have been affected by small sample size or short duration of the intervention. Therefore, further intervention studies with adequate methodology are needed to clarify this question. For the time being, whole grain consumption can be recommended as one of the features of the diet that may help control body weight but also because is associated with a lower risk to develop type 2 diabetes, cardiovascular diseases and cancer.     

Randomized controlled trial of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates on body weight and blood lipids: the CARMEN study. The Carbohydrate Ratio Management in European National diets

OBJECTIVE: To investigate the long-term effects of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates. DESIGN: Randomized controlled multicentre trial (CARMEN), in which subjects were allocated for 6 months either to a seasonal control group (no intervention) or to one of three experimental groups: a control diet group (dietary intervention typical of the average national intake); a low-fat high simple carbohydrate group; or a low-fat high complex carbohydrate group. SUBJECTS: Three hundred and ninety eight moderately obese adults. MEASUREMENTS: The change in body weight was the primary outcome; changes in body composition and blood lipids were secondary outcomes. RESULTS: Body weight loss in the low-fat high simple carbohydrate and low-fat high complex carbohydrate groups was 0.9 kg (P < 0.05) and 1.8 kg (P < 0.001), while the control diet and seasonal control groups gained weight (0.8 and 0.1 kg, NS). Fat mass changed by -1.3kg (P< 0.01), -1.8kg (P< 0.001) and +0.6kg (NS) in the low-fat high simple carbohydrate, low-fat high complex carbohydrate and control diet groups, respectively. Changes in blood lipids did not differ significantly between the dietary treatment groups. CONCLUSION: Our findings suggest that reduction of fat intake results in a modest but significant reduction in body weight and body fatness. The concomitant increase in either simple or complex carbohydrates did not indicate significant differences in weight change. No adverse effects on blood lipids were observed. These findings underline the importance of this dietary change and its potential impact on the public health implications of obesity.     

Atkins and other low-carbohydrate diets: hoax or an effective tool for weight loss?

CONTEXT: The Atkins diet books have sold more than 45 million copies over 40 years, and in the obesity epidemic this diet and accompanying Atkins food products are popular. The diet claims to be effective at producing weight loss despite ad-libitum consumption of fatty meat, butter, and other high-fat dairy products, restricting only the intake of carbohydrates to under 30 g a day. Low-carbohydrate diets have been regarded as fad diets, but recent research questions this view. STARTING POINT: A systematic review of low-carbohydrate diets found that the weight loss achieved is associated with the duration of the diet and restriction of energy intake, but not with restriction of carbohydrates. Two groups have reported longer-term randomised studies that compared instruction in the low-carbohydrate diet with a low-fat calorie-reduced diet in obese patients (N Engl J Med 2003; 348: 2082-90; Ann Intern Med 2004; 140: 778-85). Both trials showed better weight loss on the low-carbohydrate diet after 6 months, but no difference after 12 months. WHERE NEXT?: The apparent paradox that ad-libitum intake of high-fat foods produces weight loss might be due to severe restriction of carbohydrate depleting glycogen stores, leading to excretion of bound water, the ketogenic nature of the diet being appetite suppressing, the high protein-content being highly satiating and reducing spontaneous food intake, or limited food choices leading to decreased energy intake. Long-term studies are needed to measure changes in nutritional status and body composition during the low-carbohydrate diet, and to assess fasting and postprandial cardiovascular risk factors and adverse effects. Without that information, low-carbohydrate diets cannot be recommended.     

Serum levels of pancreatic enzymes in lean and obese subjects

Serum amylase and trypsin, but not lipase, were significantly lower in obese subjects than in lean subjects. Serum amylase and trypsin, but not lipase, had significant inverse correlation with body weight. Low serum amylase was associated with low protein, fat and carbohydrate intakes per kg body weight, whereas low serum trypsin was associated with low carbohydrate intake per kg body weight. Low serum pancreatic enzymes readily increased with diet therapy. It is assumed that lowered serum pancreatic enzymes in obese subjects are somehow related to their diet intake. The mechanism through which pancreatic enzymes in the blood reflect the composition of food is unclear.     

Making sense of metabolic obesity and hedonic obesity

Body weight is neither stationary nor does it change unidirectionally. Rather, body weight usually oscillates up and down around a set point. Two types of forces determine the direction of weight changes. Forces that push body weight away from the set point are defined as non‐homeostatic and are governed by multiple mechanisms, including, but not limited to, hedonic regulation of food intake. Forces that restore the set point weight are defined as homeostatic, and they operate through mechanisms that regulate short‐term energy balance driven by hunger and satiation and long‐term energy balance driven by changes in adiposity. In the normal physiological state, the deviation of body weight from the set point is usually small and temporary, and is constantly corrected by homeostatic forces. Metabolic obesity develops when body weight set point is shifted to an abnormally high level and the obese body weight becomes metabolically defended. In hedonic obesity, the obese body weight is maintained by consistent overeating due to impairments in the reward system, although the set point is not elevated. Adaptive increases in energy expenditure are elicited in hedonic obesity because body weight is elevated above the set point. Neither subtype of obesity undergoes spontaneous resolution unless the underlying disorders are corrected. In this review, the need for both appropriate patient stratification and tailored treatments is discussed in the context of the new framework of metabolic and hedonic obesity.     

Effects of dietary fibre on subjective appetite,energy intake and body weight: a systematic review of randomized controlled trials

Dietary fibres are believed to reduce subjective appetite, energy intake and body weight. However, different types of dietary fibre may affect these outcomes differently. The aim of this review was to systematically investigate the available literature on the relationship between dietary fibre types, appetite, acute and long‐term energy intake, and body weight. Fibres were grouped according to chemical structure and physicochemical properties (viscosity, solubility and fermentability). Effect rates were calculated as the proportion of all fibre–control comparisons that reduced appetite (n = 58 comparisons), acute energy intake (n = 26), long‐term energy intake (n = 38) or body weight (n = 66). For appetite, acute energy intake, long‐term energy intake and body weight, there were clear differences in effect rates depending on chemical structure. Interestingly, fibres characterized as being more viscous (e.g. pectins, β‐glucans and guar gum) reduced appetite more often than those less viscous fibres (59% vs. 14%), which also applied to acute energy intake (69% vs. 30%). Overall, effects on energy intake and body weight were relatively small, and distinct dose–response relationships were not observed. Short‐ and long‐term effects of dietary fibres appear to differ and multiple mechanisms relating to their different physicochemical properties seem to interplay. This warrants further exploration.     

Twenty-four hour energy expenditure and substrate oxidation before and after 6 months' ad libitum intake of a diet rich in simple or complex carbohydrates or a habitual diet.

OBJECTIVE: To investigate 24 h energy expenditure (24 h EE) and substrate oxidations in overweight and obese subjects before and after 6 months' ad libitum intake of a low-fat, high-simple carbohydrate diet (SCHO), a low-fat, high-complex carbohydrate diet (CCHO), or a habitual control diet (CD). SUBJECTS: Twenty-four healthy overweight and obese subjects (11 males and 13 females; body mass index 30.7+/-0.6 kg/m(2); age 42.2+/-1.8 y). MEASUREMENTS: Twenty-four hour EE, substrate oxidation rates and spontaneous physical activity (SPA) measured in a respiration chamber, and food intake. RESULTS: After the intervention no differences were seen in 24 h EE, postprandial thermogenesis, basal metabolic rate or SPA. Carbohydrate oxidation, adjusted for energy balance, increased on both carbohydrate-rich diets (SCHO 13.0%, CCHO 11.5%) and decreased on the CD diet (6.5%); however, the changes were not significantly different between diets. The opposite pattern was seen for fat oxidation, which increased by 2.9% on the CD diet and decreased by 17.1 and 25.6% on the SCHO and CCHO, respectively. The changes only differed between the CD and CCHO diet (P=0.03). CONCLUSION: Six months' ad libitum intake of a diet rich in simple or complex carbohydrates or a habitual diet induced a shift in the oxidation pattern to closely reflect the diet composition in overweight and obese subjects. No differences between diets were seen in 24 h EE.     

Good Calories, Bad Calories by Gary Taubes; New York: AA Knopf

Good Calories, Bad Calories has much useful information and is well worth reading. Gary Taubes's tenets related to obesity can be summarized in four statements (i) He believes that you can gain weight and become obese without a positive energy balance; (ii) He also believes that dietary fat is unimportant for the development of obesity; (iii) Carbohydrate, in his view, is what produces obesity and (iv) Insulin secreted by the carbohydrate is the problem in obesity. However, some of the conclusions that the author reaches are not consistent with current concepts about obesity. There are many kinds of obesity, and only some depend on diet composition. Two dietary manipulations produce obesity in susceptible people: eating a high‐fat diet and drinking sugar‐ or high‐fructose corn syrup‐sweetened beverages. Insulin is necessary but not sufficient in the diet‐dependent obesities. When diet is important, it may be the combination of fat and fructose (the deadly duo) that is most important. Regardless of diet, it is a positive energy balance over months to years that is the sine qua non for obesity. Obese people clearly eat more than do lean ones, and food‐intake records are notoriously unreliable, as documented by use of doubly labelled water. Underreporting of food intake is greater in obese than in normal‐weight people and is worse for fat than for other macronutrient groups. Accepting the concept that obesity results from a positive energy balance does not tell us why energy balance is positive. This depends on a variety of environmental factors interacting with the genetic susceptibility of certain individuals. Weight loss is related to adherence to the diet, not to its macronutrient composition.     

Effects of nonnutritive sweeteners on body weight and BMI in diverse clinical contexts: Systematic review and meta‐analysis

There is an ongoing debate about the possible influences of nonnutritive sweeteners (NNS) on body weight. We conducted a systematic review and meta‐analysis of randomized controlled trials (RCTs) with NNS to assess their impact on body weight. We systematically searched for RCTs at least 4 weeks in duration, evaluating the effect of NNS on body weight, both in subjects with healthy weight and in subjects with overweight/obesity at any age, and compared the effects of NNS vs caloric and noncaloric comparators. The primary outcome was the difference in body weight between NNS and comparators. Twenty studies were eligible (n = 2914). Participants consuming NNS showed significant weight/BMI differences favouring NNS compared with nonusers. Grouping by nature of comparator revealed that NNS vs placebo/no intervention and NNS vs water produced no effect. When comparing NNS vs sucrose, significant weight/BMI differences appeared favouring NNS. Consumption of NNS led to significantly negative weight/BMI differences in unrestricted energy diets, but not in weight‐reduction diets. Participants with overweight/obesity and adults showed significant favourable weight/BMI differences with NNS. Data suggest that replacing sugar with NNS leads to weight reduction, particularly in participants with overweight/obesity under an unrestricted diet, information that could be utilized for evidence‐based public policy decisions.