Ian D. Caterson

Diet, nutrition and the prevention of excess weight gain and obesity

OBJECTIVES To review the evidence on the diet and nutrition causes of obesity and to recommend strategies to reduce obesity prevalence. DESIGN The evidence for potential aetiological factors and strategies to reduce obesity prevalence was reviewed, and recommendations for public health action, population nutrition goals and further research were made. RESULTS Protective factors against obesity were considered to be: regular physical activity (convincing); a high intake of dietary non-starch polysaccharides (NSP)/fibre (convincing); supportive home and school environments for children (probable); and breastfeeding (probable). Risk factors for obesity were considered to be sedentary lifestyles (convincing); a high intake of energy-dense, micronutrient-poor foods (convincing); heavy marketing of energy-dense foods and fast food outlets (probable); sugar-sweetened soft drinks and fruit juices (probable); adverse social and economic conditions-developed countries, especially in women (probable). A broad range of strategies were recommended to reduce obesity prevalence including: influencing the food supply to make healthy choices easier; reducing the marketing of energy dense foods and beverages to children; influencing urban environments and transport systems to promote physical activity; developing community-wide programmes in multiple settings; increased communications about healthy eating and physical activity; and improved health services to promote breastfeeding and manage currently overweight or obese people. CONCLUSIONS The increasing prevalence of obesity is a major health threat in both low- and high income countries. Comprehensive programmes will be needed to turn the epidemic around.

Effect of Sibutramine on Cardiovascular Outcomes in Overweight and Obese Subjects

BACKGROUND The long-term effects of sibutramine treatment on the rates of cardiovascular events and cardiovascular death among subjects at high cardiovascular risk have not been established. METHODS We enrolled in our study 10,744 overweight or obese subjects, 55 years of age or older, with preexisting cardiovascular disease, type 2 diabetes mellitus, or both to assess the cardiovascular consequences of weight management with and without sibutramine in subjects at high risk for cardiovascular events. All the subjects received sibutramine in addition to participating in a weight-management program during a 6-week, single-blind, lead-in period, after which 9804 subjects underwent random assignment in a double-blind fashion to sibutramine (4906 subjects) or placebo (4898 subjects). The primary end point was the time from randomization to the first occurrence of a primary outcome event (nonfatal myocardial infarction, nonfatal stroke, resuscitation after cardiac arrest, or cardiovascular death). RESULTS The mean duration of treatment was 3.4 years. The mean weight loss during the lead-in period was 2.6 kg; after randomization, the subjects in the sibutramine group achieved and maintained further weight reduction (mean, 1.7 kg). The mean blood pressure decreased in both groups, with greater reductions in the placebo group than in the sibutramine group (mean difference, 1.2/1.4 mm Hg). The risk of a primary outcome event was 11.4% in the sibutramine group as compared with 10.0% in the placebo group (hazard ratio, 1.16; 95% confidence interval [CI], 1.03 to 1.31; P=0.02). The rates of nonfatal myocardial infarction and nonfatal stroke were 4.1% and 2.6% in the sibutramine group and 3.2% and 1.9% in the placebo group, respectively (hazard ratio for nonfatal myocardial infarction, 1.28; 95% CI, 1.04 to 1.57; P=0.02; hazard ratio for nonfatal stroke, 1.36; 95% CI, 1.04 to 1.77; P=0.03). The rates of cardiovascular death and death from any cause were not increased. CONCLUSIONS Subjects with preexisting cardiovascular conditions who were receiving long-term sibutramine treatment had an increased risk of nonfatal myocardial infarction and nonfatal stroke but not of cardiovascular death or death from any cause. (Funded by Abbott; ClinicalTrials.gov number, NCT00234832.)

Primary care referral to a commercial provider for weight loss treatment versus standard care: a randomised controlled trial

Summary Background The increasing prevalence of overweight and obesity needs effective approaches for weight loss in primary care and community settings. We compared weight loss with standard treatment in primary care with that achieved after referral by the primary care team to a commercial provider in the community. Methods In this parallel group, non-blinded, randomised controlled trial, 772 overweight and obese adults were recruited by primary care practices in Australia, Germany, and the UK. Participants were randomly assigned with a computer-generated simple randomisation sequence to receive either 12 months of standard care as defined by national treatment guidelines, or 12 months of free membership to a commercial programme (Weight Watchers), and followed up for 12 months. The primary outcome was weight change over 12 months. Analysis was by intention to treat (last observation carried forward [LOCF] and baseline observation carried forward [BOCF]) and in the population who completed the 12-month assessment. This trial is registered, number ISRCTN85485463. Findings 377 participants were assigned to the commercial programme, of whom 230 (61%) completed the 12-month assessment; and 395 were assigned to standard care, of whom 214 (54%) completed the 12-month assessment. In all analyses, participants in the commercial programme group lost twice as much weight as did those in the standard care group. Mean weight change at 12 months was −5·06 kg (SE 0·31) for those in the commercial programme versus −2·25 kg (0·21) for those receiving standard care (adjusted difference −2·77 kg, 95% CI −3·50 to −2·03) with LOCF; −4·06 kg (0·31) versus −1·77 kg (0·19; adjusted difference −2·29 kg, −2·99 to −1·58) with BOCF; and −6·65 kg (0·43) versus −3·26 kg (0·33; adjusted difference −3·16 kg, −4·23 to −2·11) for those who completed the 12-month assessment. Participants reported no adverse events related to trial participation. Interpretation Referral by a primary health-care professional to a commercial weight loss programme that provides regular weighing, advice about diet and physical activity, motivation, and group support can offer a clinically useful early intervention for weight management in overweight and obese people that can be delivered at large scale. Funding Weight Watchers International, through a grant to the UK Medical Research Council.

Ethnic comparisons of the cross‐sectional relationships between measures of body size with diabetes and hypertension

Recent estimates indicate that two billion people are overweight or obese and hence are at increased risk of cardiovascular disease and its comorbidities. However, this may be an underestimate of the true extent of the problem, as the current method used to define overweight may lack sensitivity, particularly in some ethnic groups where there may be an underestimate of risk. Measures of central obesity may be more strongly associated with cardiovascular risk, but there has been no systematic attempt to compare the strength and nature of the associations between different measures of overweight with cardiovascular risk across ethnic groups. Data from the Obesity in Asia Collaboration, comprising 21 cross‐sectional studies in the Asia‐Pacific region with information on more than 263 000 individuals, indicate that measures of central obesity, in particular, waist circumference (WC), are better discriminators of prevalent diabetes and hypertension in Asians and Caucasians, and are more strongly associated with prevalent diabetes (but not hypertension), compared with body mass index (BMI).

Prevention Conference VII Obesity, a Worldwide Epidemic Related to Heart Disease and Stroke: Group III: Worldwide Comorbidities of Obesity

Current concerns about the increased risk of cardiovascular and other diseases induced by excessive weight gain in children and adults have been highlighted by the Surgeon General’s report on the problem of obesity in the United States.1 This call to action followed a global analysis of the problem of excess weight and how to define and combat it that was undertaken by the World Health Organization (WHO) in 19972 and an analogous National Institutes of Health (NIH) assessment and reclassification of US rates of overweight and obesity in 1998.3 It is generally accepted that body mass index (BMI), or weight in kilograms per square meter of height, is a convenient measure of an approximate height-independent index of both children and adults’ weight for height and provides a crude indication of the body’s fat content. It is becoming clear that different ethnic groups have different proportions of fat-to-lean tissues at equivalent BMIs4,5 and that the magnitude of the multiple comorbidities associated with higher BMIs also may differ among different ethnic groups for reasons that may reflect the impact of environmental–genetic interactions. Nevertheless, current international comparisons use a standard format and classification system. In all societies a spectrum of BMIs exists for children and adults of all ages. Individual positions within the percentile range tend to remain the same as children grow and adults steadily gain weight. As the average weight of children and adults increases, so does the spread of BMIs, with a marked progressive increase in the numbers with very high BMIs (see Figure 1). Thus, the escalation in obesity rates reflects the upward shift in body weights of the whole population in response to environmental changes. Adults with a BMI of 18.5 to 24.9 are categorized as being of normal weight, on the basis of …

The impact of obesity on the musculoskeletal system

Obesity is associated with a range of disabling musculoskeletal conditions in adults. As the prevalence of obesity increases, the societal burden of these chronic musculosketelal conditions, in terms of disability, health-related quality of life, and health-care costs, also increases. Research exploring the nature and strength of the associations between obesity and musculoskeletal conditions is accumulating, providing a better understanding of underlying mechanisms. Weight reduction is important in ameliorating some of the manifestations of musculoskeletal disease and improving function.

Increased Gut Permeability and Microbiota Change Associate with Mesenteric Fat Inflammation and Metabolic Dysfunction in Diet-Induced Obese Mice

We investigated the relationship between gut health, visceral fat dysfunction and metabolic disorders in diet-induced obesity. C57BL/6J mice were fed control or high saturated fat diet (HFD). Circulating glucose, insulin and inflammatory markers were measured. Proximal colon barrier function was assessed by measuring transepithelial resistance and mRNA expression of tight-junction proteins. Gut microbiota profile was determined by 16S rDNA pyrosequencing. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 mRNA levels were measured in proximal colon, adipose tissue and liver using RT-qPCR. Adipose macrophage infiltration (F4/80+) was assessed using immunohistochemical staining. HFD mice had a higher insulin/glucose ratio (P = 0.020) and serum levels of serum amyloid A3 (131%; P = 0.008) but reduced circulating adiponectin (64%; P = 0.011). In proximal colon of HFD mice compared to mice fed the control diet, transepithelial resistance and mRNA expression of zona occludens 1 were reduced by 38% (P<0.001) and 40% (P = 0.025) respectively and TNF-α mRNA level was 6.6-fold higher (P = 0.037). HFD reduced Lactobacillus (75%; P<0.001) but increased Oscillibacter (279%; P = 0.004) in fecal microbiota. Correlations were found between abundances of Lactobacillus (r = 0.52; P = 0.013) and Oscillibacter (r = −0.55; P = 0.007) with transepithelial resistance of the proximal colon. HFD increased macrophage infiltration (58%; P = 0.020), TNF-α (2.5-fold, P<0.001) and IL-6 mRNA levels (2.5-fold; P = 0.008) in mesenteric fat. Increased macrophage infiltration in epididymal fat was also observed with HFD feeding (71%; P = 0.006) but neither TNF-α nor IL-6 was altered. Perirenal and subcutaneous adipose tissue showed no signs of inflammation in HFD mice. The current results implicate gut dysfunction, and attendant inflammation of contiguous adipose, as salient features of the metabolic dysregulation of diet-induced obesity.

Obesity and Risk of Low Self-esteem: A Statewide Survey of Australian Children.

OBJECTIVE. There is variation in the psychological distress associated with child obesity. Low self-esteem, when observed, provides very little information about the nature of the distress and no indication of the proportion of obese children affected. This study used a domain approach to self-competence to evaluate self-esteem in a representative sample of Australian children. PARTICIPANTS AND METHODS. A total of 2813 children (mean age: 11.3 years) took part in the study. They were recruited from 55 schools and were all in the last 2 years of primary school. Participants completed the Self-perception Profile for Children, a measure of body shape perception, and their height and weight were measured. RESULTS. Obese children had significantly lower perceived athletic competence, physical appearance, and global self-worth than their normal weight peers. Obese girls scored lower in these domains than obese boys and also had reduced perceived social acceptance. Obese children were 2–4 times more likely than their normal weight peers to have low domain competence. In terms of prevalence, 1 of 3 obese boys and 2 of 3 obese girls had low appearance competence, and 10% and 20%, respectively, had low global self-worth. Body dissatisfaction mediated most of the association between BMI and low competence in boys but not in girls. CONCLUSIONS. Obesity impacts the self-perception of children entering adolescence, especially in girls, but in selected areas of competence. Obese children are at particular risk of low perceived competence in sports, physical appearance, and peer engagement. Not all obese children are affected, although the reasons for their resilience are unclear. Quantifying risk of psychological distress alongside biomedical risk should help in arguing for more resources in child obesity treatment.

Association of serum leptin with hypoventilation in human obesity

Background: Leptin is a protein hormone produced by fat cells of mammals. It acts within the hypothalamus via a specific receptor to reduce appetite and increase energy expenditure. Plasma leptin levels correlate closely with total body fat mass operating via a central feedback mechanism. In human obesity serum leptin levels are up to four times higher than in lean subjects, indicating a failure of the feedback loop and central leptin resistance. In leptin deficient obese mice (ob/ob mice) leptin infusion reverses hypoventilation. It was hypothesised that a relative deficiency in CNS leptin, indicated by high circulating leptin levels, may be implicated in the pathogenesis of obesity hypoventilation syndrome (OHS). Methods: Fasting morning leptin levels were measured in obese and non-obese patients with and without daytime hypercapnia (n=56). Sleep studies, anthropometric data, spirometric parameters, and awake arterial blood gas tensions were measured in each patient. Results: In the whole group serum leptin levels correlated closely with % body fat (r=0.77). Obese hypercapnic patients (mean (SD) % body fat 43.8 (6.0)%) had higher fasting serum leptin levels than eucapnic patients (mean % body fat 40.8 (6.2)%), with mean (SD) leptin levels of 39.1 (17.9) and 21.4 (11.4) ng/ml, respectively (p<0.005). Serum leptin (odds ratio (OR) 1.12, 95% CI 1.03 to 1.22) was a better predictor than % body fat (OR 0.92, 95% CI 0.76 to 1.1) for the presence of hypercapnia. Conclusions: Hyperleptinaemia is associated with hypercapnic respiratory failure in obesity. Treatment with leptin or its analogues may have a role in OHS provided central leptin resistance can be overcome.

Prevention Conference VII Obesity, a Worldwide Epidemic Related to Heart Disease and Stroke: Executive Summary

On April 27 and 28, 2002, the American Heart Association (AHA) sponsored a scientific conference, “Obesity, a Worldwide Epidemic Related to Heart Disease and Stroke,” in Honolulu, Hawaii. The purpose of the conference was to develop a plan to reduce cardiovascular diseases (CVDs) associated with overweight and obesity. This report discusses the activities of the 4 working groups held before the conference, presentations at the conference, and extensive discussions among working group members after the conference. The primary objectives of this meeting were to The major findings of each working group are presented in this Executive Summary of the conference proceedings. The complete conference report with references is available online at http://www.circulationaha.org in the November 2, 2004, issue of Circulation . The prevalence of obesity is increasing in virtually all populations and age groups worldwide. Although this increase is most evident in the United States, it is not limited to the more developed, affluent nations of the world. The escalation in obesity rates reflects the upward shift in body weights of individual populations in response to environmental changes. BMI, or weight in kilograms per square meter of height (kg/m2), generally is accepted as a convenient measurement that provides a crude indication of body fat. The classifications of normal weight (BMI 18.5 to 24.9), overweight (BMI 25.0 to 29.9), and obesity (BMI >30.0) are somewhat arbitrary but are based on international analyses of the health impact of different BMIs. By using approaches similar to those used for birth cohort trends in cholesterol …