Summary
Imbalances in the gut microbiota, the bacteria that inhabit the intestines, are central to the pathogenesis of obesity. This systematic review assesses the association between the gut ...microbiota and weight loss in overweight/obese adults and its potential manipulation as a target for treating obesity. This review identified 43 studies using the keywords ‘overweight’ or ‘obesity’ and ‘microbiota’ and related terms; among these studies, 17 used dietary interventions, 11 used bariatric surgery and 15 used microbiota manipulation. The studies differed in their methodologies as well as their intervention lengths. Restrictive diets decreased the microbiota abundance, correlated with nutrient deficiency rather than weight loss and generally reduced the butyrate producers Firmicutes, Lactobacillus sp. and Bifidobacterium sp. The impact of surgical intervention depended on the given technique and showed a similar effect on butyrate producers, in addition to increasing the presence of the Proteobacteria phylum, which is related to changes in the intestinal absorptive surface, pH and digestion time. Probiotics differed in strain and duration with diverse effects on the microbiota, and they tended to reduce body fat. Prebiotics had a bifidogenic effect and increased butyrate producers, likely due to cross‐feeding interactions, contributing to the gut barrier and improving metabolic outcomes. All of the interventions under consideration had impacts on the gut microbiota, although they did not always correlate with weight loss. These results show that restrictive diets and bariatric surgery reduce microbial abundance and promote changes in microbial composition that could have long‐term detrimental effects on the colon. In contrast, prebiotics might restore a healthy microbiome and reduce body fat.
Author Interview on The Brian Lehrer Show America is a
weight-obsessed nation. Over the last decade, there's been an
explosion of concern in the U.S. about people getting fatter.
Plaintiffs are now ...filing lawsuits arguing that discrimination
against fat people should be illegal. Fat Rights
asks the first provocative questions that need to be raised about
adding weight to lists of currently protected traits like race,
gender, and disability. Is body fat an indicator of a character
flaw or of incompetence on the job? Does it pose risks or costs to
employers they should be allowed to evade? Or is it simply a
stigmatized difference that does not bear on the ability to perform
most jobs? Could we imagine fatness as part of workplace diversity?
Considering fat discrimination prompts us to rethink these basic
questions that lawyers, judges, and ordinary citizens ask before a
new trait begins to look suitable for antidiscrimination coverage.
Fat Rights draws on little-known legal cases
brought by fat citizens as well as significant lawsuits over other
forms of bodily difference (such as transgenderism), asking why the
boundaries of our antidiscrimination laws rest where they do.
Fatness, argues Kirkland, is both similar to and provocatively
different from other protected traits, raising long-standing
dilemmas in antidiscrimination law into stark relief. Though
options for defending difference may be scarce, Kirkland evaluates
the available strategies and proposes new ways of navigating this
new legal question. Fat Rights enters the fray of
the obesity debate from a new perspective: our inherited civil
rights tradition. The scope is broad, covering much more than just
weight discrimination and drawing the reader into the larger
context of antidiscrimination protections and how they can be
justified for a new group.
To investigate the underlying mechanisms behind changes in glucose homeostasis with delivery of propionate to the human colon by comprehensive and coordinated analysis of gut bacterial composition, ...plasma metabolome and immune responses.
Twelve non-diabetic adults with overweight and obesity received 20 g/day of inulin-propionate ester (IPE), designed to selectively deliver propionate to the colon, a high-fermentable fibre control (inulin) and a low-fermentable fibre control (cellulose) in a randomised, double-blind, placebo-controlled, cross-over design. Outcome measurements of metabolic responses, inflammatory markers and gut bacterial composition were analysed at the end of each 42-day supplementation period.
Both IPE and inulin supplementation improved insulin resistance compared with cellulose supplementation, measured by homeostatic model assessment 2 (mean±SEM 1.23±0.17 IPE vs 1.59±0.17 cellulose, p=0.001; 1.17±0.15 inulin vs 1.59±0.17 cellulose, p=0.009), with no differences between IPE and inulin (p=0.272). Fasting insulin was only associated positively with plasma tyrosine and negatively with plasma glycine following inulin supplementation. IPE supplementation decreased proinflammatory interleukin-8 levels compared with cellulose, while inulin had no impact on the systemic inflammatory markers studied. Inulin promoted changes in gut bacterial populations at the class level (increased Actinobacteria and decreased Clostridia) and order level (decreased Clostridiales) compared with cellulose, with small differences at the species level observed between IPE and cellulose.
These data demonstrate a distinctive physiological impact of raising colonic propionate delivery in humans, as improvements in insulin sensitivity promoted by IPE and inulin were accompanied with different effects on the plasma metabolome, gut bacterial populations and markers of systemic inflammation.
Most individuals with type 2 diabetes also have obesity, and treatment with some diabetes medications, including insulin, can cause further weight gain. No approved chronic weight management ...medications have been prospectively investigated in individuals with overweight or obesity and insulin-treated type 2 diabetes. The primary objective of this study was to assess the effect of liraglutide 3.0 mg versus placebo on weight loss in this population.
Satiety and Clinical Adiposity-Liraglutide Evidence (SCALE) Insulin was a 56-week, randomized, double-blind, placebo-controlled, multinational, multicenter trial in individuals with overweight or obesity and type 2 diabetes treated with basal insulin and ≤2 oral antidiabetic drugs.
Individuals were randomized to liraglutide 3.0 mg (
= 198) or placebo (
= 198), combined with intensive behavioral therapy (IBT). At 56 weeks, mean weight change was -5.8% for liraglutide 3.0 mg versus -1.5% with placebo (estimated treatment difference -4.3% 95% CI -5.5; -3.2;
< 0.0001). With liraglutide 3.0 mg, 51.8% of individuals achieved ≥5% weight loss versus 24.0% with placebo (odds ratio 3.41 95% CI 2.19; 5.31;
< 0.0001). Liraglutide 3.0 mg was associated with significantly greater reductions in mean HbA
and mean daytime glucose values and less need for insulin versus placebo, despite a treat-to-glycemic-target protocol. More hypoglycemic events were observed with placebo than liraglutide 3.0 mg. No new safety or tolerability issues were observed.
In individuals with overweight or obesity and insulin-treated type 2 diabetes, liraglutide 3.0 mg as an adjunct to IBT was superior to placebo regarding weight loss and improved glycemic control despite lower doses of basal insulin and without increases in hypoglycemic events.
Low-grade inflammation is a characteristic of the obese state, and adipose tissue releases many inflammatory mediators. The source of these mediators within adipose tissue is not clear, but ...infiltrating macrophages seem to be especially important, although adipocytes themselves play a role. Obese people have higher circulating concentrations of many inflammatory markers than lean people do, and these are believed to play a role in causing insulin resistance and other metabolic disturbances. Blood concentrations of inflammatory markers are lowered following weight loss. In the hours following the consumption of a meal, there is an elevation in the concentrations of inflammatory mediators in the bloodstream, which is exaggerated in obese subjects and in type 2 diabetics. Both high-glucose and high-fat meals may induce postprandial inflammation, and this is exaggerated by a high meal content of advanced glycation end products (AGE) and partly ablated by inclusion of certain antioxidants or antioxidant-containing foods within the meal. Healthy eating patterns are associated with lower circulating concentrations of inflammatory markers. Among the components of a healthy diet, whole grains, vegetables and fruits, and fish are all associated with lower inflammation. AGE are associated with enhanced oxidative stress and inflammation. SFA and trans-MUFA are pro-inflammatory, while PUFA, especially long-chain n-3 PUFA, are anti-inflammatory. Hyperglycaemia induces both postprandial and chronic low-grade inflammation. Vitamin C, vitamin E and carotenoids decrease the circulating concentrations of inflammatory markers. Potential mechanisms are described and research gaps, which limit our understanding of the interaction between diet and postprandial and chronic low-grade inflammation, are identified.
Obesity increases risk for all-cause and breast cancer mortality and comorbidities in women who have been diagnosed and treated for breast cancer. The Exercise and Nutrition to Enhance Recovery and ...Good Health for You (ENERGY) study is the largest weight loss intervention trial among survivors of breast cancer to date.
In this multicenter trial, 692 overweight/obese women who were, on average, 2 years since primary treatment for early-stage breast cancer were randomly assigned to either a group-based behavioral intervention, supplemented with telephone counseling and tailored newsletters, to support weight loss or a less intensive control intervention and observed for 2 years. Weight and blood pressure were measured at 6, 12, 18, and 24 months. Longitudinal mixed models were used to analyze change over time.
At 12 months, mean weight loss was 6.0% of initial weight in the intervention group and 1.5% in the control group (P<.001). At 24 months, mean weight loss in the intervention and control groups was 3.7% and 1.3%, respectively (P<.001). Favorable effects of the intervention on physical activity and blood pressure were observed. The weight loss intervention was more effective among women older than 55 years than among younger women.
A behavioral weight loss intervention can lead to clinically meaningful weight loss in overweight/obese survivors of breast cancer. These findings support the need to conduct additional studies to test methods that support sustained weight loss and to examine the potential benefit of intentional weight loss on breast cancer recurrence and survival.
To assess whether the risk of gestational diabetes mellitus (GDM) may be lowered and glucose metabolism improved by daily administration of fish oil and/or probiotic supplements in overweight and ...obese pregnant women.
We randomized in a double-blind manner 439 women (mean 13.9 ± 2.1 gestational weeks gw) into four intervention groups: fish oil + placebo, probiotics + placebo, fish oil + probiotics, and placebo + placebo. Fish oil (1.9 g docosahexaenoic acid and 0.22 g eicosapentaenoic acid) and probiotic supplements (
HN001 and
420, 10
colony-forming units each) were provided for daily consumption from randomization beyond delivery. Primary outcomes were the incidence of GDM diagnosed with oral glucose tolerance test targeted at 24-28 gw and the change in fasting glucose between randomization and late pregnancy (mean 35.2 ± 0.9 gw). Insulin concentration, insulin resistance HOMA2-IR index, and pregnancy outcomes were determined, as were adverse effects related to the intervention. Analyses were by intent to treat.
No differences were found among the intervention groups in the maternal and neonatal pregnancy outcomes or side effects related to the intervention (
> 0.05). The proportion of women with GDM (94 of 377; fish oil + placebo, 23 of 96, 24.0%; probiotics + placebo, 25 of 99, 25.3%; fish oil + probiotics, 26 of 91, 28.6%; and placebo + placebo, 20 of 91, 22.0%) and the change in glucose, insulin, or HOMA2-IR (
= 364) did not differ among the intervention groups (
> 0.11 for all comparisons).
An intervention with fish oil and/or probiotics during pregnancy seemed to be both safe and well tolerated but conferred no benefits in lowering the risk of GDM or improving glucose metabolism in overweight and obese women.
Background
The global prevalence of childhood and adolescent obesity is high. Lifestyle changes towards a healthy diet, increased physical activity and reduced sedentary activities are recommended to ...prevent and treat obesity. Evidence suggests that changing these health behaviours can benefit cognitive function and school achievement in children and adolescents in general. There are various theoretical mechanisms that suggest that children and adolescents with excessive body fat may benefit particularly from these interventions.
Objectives
To assess whether lifestyle interventions (in the areas of diet, physical activity, sedentary behaviour and behavioural therapy) improve school achievement, cognitive function (e.g. executive functions) and/or future success in children and adolescents with obesity or overweight, compared with standard care, waiting‐list control, no treatment, or an attention placebo control group.
Search methods
In February 2017, we searched CENTRAL, MEDLINE and 15 other databases. We also searched two trials registries, reference lists, and handsearched one journal from inception. We also contacted researchers in the field to obtain unpublished data.
Selection criteria
We included randomised and quasi‐randomised controlled trials (RCTs) of behavioural interventions for weight management in children and adolescents with obesity or overweight. We excluded studies in children and adolescents with medical conditions known to affect weight status, school achievement and cognitive function. We also excluded self‐ and parent‐reported outcomes.
Data collection and analysis
Four review authors independently selected studies for inclusion. Two review authors extracted data, assessed quality and risks of bias, and evaluated the quality of the evidence using the GRADE approach. We contacted study authors to obtain additional information. We used standard methodological procedures expected by Cochrane. Where the same outcome was assessed across different intervention types, we reported standardised effect sizes for findings from single‐study and multiple‐study analyses to allow comparison of intervention effects across intervention types. To ease interpretation of the effect size, we also reported the mean difference of effect sizes for single‐study outcomes.
Main results
We included 18 studies (59 records) of 2384 children and adolescents with obesity or overweight. Eight studies delivered physical activity interventions, seven studies combined physical activity programmes with healthy lifestyle education, and three studies delivered dietary interventions. We included five RCTs and 13 cluster‐RCTs. The studies took place in 10 different countries. Two were carried out in children attending preschool, 11 were conducted in primary/elementary school‐aged children, four studies were aimed at adolescents attending secondary/high school and one study included primary/elementary and secondary/high school‐aged children. The number of studies included for each outcome was low, with up to only three studies per outcome. The quality of evidence ranged from high to very low and 17 studies had a high risk of bias for at least one item. None of the studies reported data on additional educational support needs and adverse events.
Compared to standard practice, analyses of physical activity‐only interventions suggested high‐quality evidence for improved mean cognitive executive function scores. The mean difference (MD) was 5.00 scale points higher in an after‐school exercise group compared to standard practice (95% confidence interval (CI) 0.68 to 9.32; scale mean 100, standard deviation 15; 116 children, 1 study). There was no statistically significant beneficial effect in favour of the intervention for mathematics, reading, or inhibition control. The standardised mean difference (SMD) for mathematics was 0.49 (95% CI ‐0.04 to 1.01; 2 studies, 255 children, moderate‐quality evidence) and for reading was 0.10 (95% CI ‐0.30 to 0.49; 2 studies, 308 children, moderate‐quality evidence). The MD for inhibition control was ‐1.55 scale points (95% CI ‐5.85 to 2.75; scale range 0 to 100; SMD ‐0.15, 95% CI ‐0.58 to 0.28; 1 study, 84 children, very low‐quality evidence). No data were available for average achievement across subjects taught at school.
There was no evidence of a beneficial effect of physical activity interventions combined with healthy lifestyle education on average achievement across subjects taught at school, mathematics achievement, reading achievement or inhibition control. The MD for average achievement across subjects taught at school was 6.37 points lower in the intervention group compared to standard practice (95% CI ‐36.83 to 24.09; scale mean 500, scale SD 70; SMD ‐0.18, 95% CI ‐0.93 to 0.58; 1 study, 31 children, low‐quality evidence). The effect estimate for mathematics achievement was SMD 0.02 (95% CI ‐0.19 to 0.22; 3 studies, 384 children, very low‐quality evidence), for reading achievement SMD 0.00 (95% CI ‐0.24 to 0.24; 2 studies, 284 children, low‐quality evidence), and for inhibition control SMD ‐0.67 (95% CI ‐1.50 to 0.16; 2 studies, 110 children, very low‐quality evidence). No data were available for the effect of combined physical activity and healthy lifestyle education on cognitive executive functions.
There was a moderate difference in the average achievement across subjects taught at school favouring interventions targeting the improvement of the school food environment compared to standard practice in adolescents with obesity (SMD 0.46, 95% CI 0.25 to 0.66; 2 studies, 382 adolescents, low‐quality evidence), but not with overweight. Replacing packed school lunch with a nutrient‐rich diet in addition to nutrition education did not improve mathematics (MD ‐2.18, 95% CI ‐5.83 to 1.47; scale range 0 to 69; SMD ‐0.26, 95% CI ‐0.72 to 0.20; 1 study, 76 children, low‐quality evidence) and reading achievement (MD 1.17, 95% CI ‐4.40 to 6.73; scale range 0 to 108; SMD 0.13, 95% CI ‐0.35 to 0.61; 1 study, 67 children, low‐quality evidence).
Authors' conclusions
Despite the large number of childhood and adolescent obesity treatment trials, we were only able to partially assess the impact of obesity treatment interventions on school achievement and cognitive abilities. School and community‐based physical activity interventions as part of an obesity prevention or treatment programme can benefit executive functions of children with obesity or overweight specifically. Similarly, school‐based dietary interventions may benefit general school achievement in children with obesity. These findings might assist health and education practitioners to make decisions related to promoting physical activity and healthy eating in schools. Future obesity treatment and prevention studies in clinical, school and community settings should consider assessing academic and cognitive as well as physical outcomes.
Background
Adolescent overweight and obesity has increased globally, and can be associated with short‐ and long‐term health consequences. Modifying known dietary and behavioural risk factors through ...behaviour changing interventions (BCI) may help to reduce childhood overweight and obesity. This is an update of a review published in 2009.
Objectives
To assess the effects of diet, physical activity and behavioural interventions for the treatment of overweight or obese adolescents aged 12 to 17 years.
Search methods
We performed a systematic literature search in: CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, LILACS, and the trial registers ClinicalTrials.gov and ICTRP Search Portal. We checked references of identified studies and systematic reviews. There were no language restrictions. The date of the last search was July 2016 for all databases.
Selection criteria
We selected randomised controlled trials (RCTs) of diet, physical activity and behavioural interventions for treating overweight or obesity in adolescents aged 12 to 17 years.
Data collection and analysis
Two review authors independently assessed risk of bias, evaluated the overall quality of the evidence using the GRADE instrument and extracted data following the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions. We contacted trial authors for additional information.
Main results
We included 44 completed RCTs (4781 participants) and 50 ongoing studies. The number of participants in each trial varied (10 to 521) as did the length of follow‐up (6 to 24 months). Participants ages ranged from 12 to 17.5 years in all trials that reported mean age at baseline. Most of the trials used a multidisciplinary intervention with a combination of diet, physical activity and behavioural components. The content and duration of the intervention, its delivery and the comparators varied across trials. The studies contributing most information to outcomes of weight and body mass index (BMI) were from studies at a low risk of bias, but studies with a high risk of bias provided data on adverse events and quality of life.
The mean difference (MD) of the change in BMI at the longest follow‐up period in favour of BCI was ‐1.18 kg/m2 (95% confidence interval (CI) ‐1.67 to ‐0.69); 2774 participants; 28 trials; low quality evidence. BCI lowered the change in BMI z score by ‐0.13 units (95% CI ‐0.21 to ‐0.05); 2399 participants; 20 trials; low quality evidence. BCI lowered body weight by ‐3.67 kg (95% CI ‐5.21 to ‐2.13); 1993 participants; 20 trials; moderate quality evidence. The effect on weight measures persisted in trials with 18 to 24 months' follow‐up for both BMI (MD ‐1.49 kg/m2 (95% CI ‐2.56 to ‐0.41); 760 participants; 6 trials and BMI z score MD ‐0.34 (95% CI ‐0.66 to ‐0.02); 602 participants; 5 trials).
There were subgroup differences showing larger effects for both BMI and BMI z score in studies comparing interventions with no intervention/wait list control or usual care, compared with those testing concomitant interventions delivered to both the intervention and control group. There were no subgroup differences between interventions with and without parental involvement or by intervention type or setting (health care, community, school) or mode of delivery (individual versus group).
The rate of adverse events in intervention and control groups was unclear with only five trials reporting harms, and of these, details were provided in only one (low quality evidence). None of the included studies reported on all‐cause mortality, morbidity or socioeconomic effects.
BCIs at the longest follow‐up moderately improved adolescent's health‐related quality of life (standardised mean difference 0.44 ((95% CI 0.09 to 0.79); P = 0.01; 972 participants; 7 trials; 8 comparisons; low quality of evidence) but not self‐esteem.
Trials were inconsistent in how they measured dietary intake, dietary behaviours, physical activity and behaviour.
Authors' conclusions
We found low quality evidence that multidisciplinary interventions involving a combination of diet, physical activity and behavioural components reduce measures of BMI and moderate quality evidence that they reduce weight in overweight or obese adolescents, mainly when compared with no treatment or waiting list controls. Inconsistent results, risk of bias or indirectness of outcome measures used mean that the evidence should be interpreted with caution. We have identified a large number of ongoing trials (50) which we will include in future updates of this review.
Background
Child overweight and obesity has increased globally, and can be associated with short‐ and long‐term health consequences.
Objectives
To assess the effects of diet, physical activity, and ...behavioural interventions for the treatment of overweight or obesity in preschool children up to the age of 6 years.
Search methods
We performed a systematic literature search in the databases Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, and LILACS, as well as in the trial registers ClinicalTrials.gov and ICTRP Search Portal. We also checked references of identified trials and systematic reviews. We applied no language restrictions. The date of the last search was March 2015 for all databases.
Selection criteria
We selected randomised controlled trials (RCTs) of diet, physical activity, and behavioural interventions for treating overweight or obesity in preschool children aged 0 to 6 years.
Data collection and analysis
Two review authors independently assessed risk of bias, evaluated the overall quality of the evidence using the GRADE instrument, and extracted data following the Cochrane Handbook for Systematic Reviews of Interventions. We contacted trial authors for additional information.
Main results
We included 7 RCTs with a total of 923 participants: 529 randomised to an intervention and 394 to a comparator. The number of participants per trial ranged from 18 to 475. Six trials were parallel RCTs, and one was a cluster RCT. Two trials were three‐arm trials, each comparing two interventions with a control group. The interventions and comparators in the trials varied. We categorised the comparisons into two groups: multicomponent interventions and dietary interventions. The overall quality of the evidence was low or very low, and six trials had a high risk of bias on individual 'Risk of bias' criteria. The children in the included trials were followed up for between six months and three years.
In trials comparing a multicomponent intervention with usual care, enhanced usual care, or information control, we found a greater reduction in body mass index (BMI) z score in the intervention groups at the end of the intervention (6 to 12 months): mean difference (MD) ‐0.3 units (95% confidence interval (CI) ‐0.4 to ‐0.2); P < 0.00001; 210 participants; 4 trials; low‐quality evidence, at 12 to 18 months' follow‐up: MD ‐0.4 units (95% CI ‐0.6 to ‐0.2); P = 0.0001; 202 participants; 4 trials; low‐quality evidence, and at 2 years' follow‐up: MD ‐0.3 units (95% CI ‐0.4 to ‐0.1); 96 participants; 1 trial; low‐quality evidence.
One trial stated that no adverse events were reported; the other trials did not report on adverse events. Three trials reported health‐related quality of life and found improvements in some, but not all, aspects. Other outcomes, such as behaviour change and parent‐child relationship, were inconsistently measured.
One three‐arm trial of very low‐quality evidence comparing two types of diet with control found that both the dairy‐rich diet (BMI z score change MD ‐0.1 units (95% CI ‐0.11 to ‐0.09); P < 0.0001; 59 participants) and energy‐restricted diet (BMI z score change MD ‐0.1 units (95% CI ‐0.11 to ‐0.09); P < 0.0001; 57 participants) resulted in greater reduction in BMI than the comparator at the end of the intervention period, but only the dairy‐rich diet maintained this at 36 months' follow‐up (BMI z score change in MD ‐0.7 units (95% CI ‐0.71 to ‐0.69); P < 0.0001; 52 participants). The energy‐restricted diet had a worse BMI outcome than control at this follow‐up (BMI z score change MD 0.1 units (95% CI 0.09 to 0.11); P < 0.0001; 47 participants). There was no substantial difference in mean daily energy expenditure between groups. Health‐related quality of life, adverse effects, participant views, and parenting were not measured.
No trial reported on all‐cause mortality, morbidity, or socioeconomic effects.
All results should be interpreted cautiously due to their low quality and heterogeneous interventions and comparators.
Authors' conclusions
Muticomponent interventions appear to be an effective treatment option for overweight or obese preschool children up to the age of 6 years. However, the current evidence is limited, and most trials had a high risk of bias. Most trials did not measure adverse events. We have identified four ongoing trials that we will include in future updates of this review.
The role of dietary interventions is more equivocal, with one trial suggesting that dairy interventions may be effective in the longer term, but not energy‐restricted diets. This trial also had a high risk of bias.
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