Obesity Reviews

Neovius, M.; Janson, A.; Rössner, S.

doi: 10.1111/j.1467-789x.2006.00190.xpmid: 16436097

Although the prevalence of obesity in Sweden still is low in an international perspective, the development during the last decades is alarming in adults, adolescents and children alike. The prevalence of obesity [body mass index (BMI) > 30 kg m−2] in adults has doubled during the last two decades and is now approximately 10% in both men and women, according to estimates based on self‐reported BMI from repeated random samples of the population. However, prevalence estimates based on measured BMI from the WHO MONICA study indicate that the self‐reported data result in underestimates. In military conscripts, the prevalence of obesity (BMI > 30 kg m−2) almost quadrupled to 3.2% from 1971 to 1995, while the overweight fraction (BMI > 25 kg m−2) more than doubled to 16.3%. The development in younger age groups seems to be similar; the prevalence of overweight [International Obesity Task Force (IOTF)/Cole] in children aged 10 years in Gothenburg has doubled to 18% (2.9% obese) during the last decade, and similar figures have been reported in other studies. However, most reports on childhood overweight stem from the larger metropolitan areas, and hence may be underestimates because of the urban–rural influence on obesity‐status. Recent data from non‐urban areas in the northern part of Sweden estimate the prevalence of overweight (BMI > 20 kg m−2) in 10‐year‐olds to above 30%. In the most comprehensive study in children, including both rural and urban areas, BMI was measured among all children aged 10 years (n = 5517; 92.7% of the population) in the county of Ostergotland, and the prevalence of overweight (IOTF/Cole) was 22% in both boys and girls, of which 4% and 5% were obese respectively.

Phipps, S. A.; Burton, P. S.; Osberg, L. S.; Lethbridge, L. N.

doi: 10.1111/j.1467-789X.2006.00217.xpmid: 16436098

The goal of this paper is to compare the extent of child obesity in Canada, Norway and the United States. As child poverty is an important correlate of child obesity, we wish to examine the potential role of international differences in child poverty in explaining international differences in the extent of child obesity. We use three representative microdata surveys containing parental reports of child height and weight collected in the mid‐1990s in Canada, Norway and the US. We calculate both the prevalence and proportional severity of child obesity for 6–11‐year‐old children in each country, and represent the ‘extent’ of obesity diagrammatically. Differences in patterns of child poverty are similarly depicted. Obesity extent is also compared for poor and non‐poor children in Canada and the US. Finally, child obesity in the three countries is compared using only non‐poor children where we find that the extent of child obesity is much lower in Norway than in Canada or the US. The pattern apparent for obesity is remarkably similar to that found for child poverty. In Canada and especially in the US, we find a much greater extent of obesity for poor than non‐poor children. However, when we compare only non‐poor children in the three countries, although the magnitude of difference is smaller, it remains clear that Norwegian children are much less likely to be obese. Policy and research directed towards reducing the extent of child obesity in both Canada and the US should pay particular attention to issues of child poverty.

Wearing, S. C.; Hennig, E. M.; Byrne, N. M.; Steele, J. R.; Hills, A. P.

doi: 10.1111/j.1467-789X.2006.00215.xpmid: 16436099

In spite of significant advances in the knowledge and understanding of the multi‐factorial nature of obesity, many questions regarding the specific consequences of the disease remain unanswered. In particular, there is a relative dearth of information pertaining to the functional limitations imposed by overweight and obesity. The limited number of studies to date have mainly focused on the effect of obesity on the temporospatial characteristics of walking, plantar foot pressures, muscular strength and, to a lesser extent, postural balance. Collectively, these studies have implied that the functional limitations imposed by the additional loading of the locomotor system in obesity result in aberrant mechanics and the potential for musculoskeletal injury. Despite the greater prevalence of musculoskeletal disorders in the obese, there has been surprisingly little empirical investigation pertaining to the biomechanics of activities of daily living or into the mechanical and neuromuscular factors that may predispose the obese to injury. A better appreciation of the implications of increased levels of body adiposity on the movement capabilities of the obese would afford a greater opportunity to provide meaningful support in preventing, treating and managing the condition and its sequelae. Moreover, there is an urgent need to establish the physical consequences of continued repetitive loading of major structures of the body, particularly of the lower limbs in the obese, during the diverse range of activities of daily living.

Dolan, M. S.; Weiss, L. A.; Lewis, R. A.; Pietrobelli, A.; Heo, M.; Faith, M. S.

doi: 10.1111/j.1467-789X.2006.00219.xpmid: 16436100

The US government initiated a national health campaign targeting 100 ‘small step’ lifestyle changes to combat obesity. Small Step ♯67 advocates stair instead of escalator usage in public settings. The aim of this study is to evaluate the effects of motivational signs prompting stair use over escalator use on pedestrians’ stair usage in commuter settings. Eight studies, testing the effects of motivational prompts on stair vs. escalator usage in public settings, were reviewed. Participant and study attributes were descriptively coded. Effect size was calculated as the change in percent units of stair users during the intervention phases vs. the baseline phase. The average study included ∼45 000 observations that were recorded across an average of 15 weeks of intervention. The mean ± SD change in percent units of stair users was 2.8% ± 2.4% (P < 0.001), and effects were twice as large in females (4.8%) as in males (2.4%). The number of stairs/building, baseline stair use, and total intervention weeks predicted change in stair use, although the effects were clinically miniscule. In a hypothetical city intervention, we projected that a 2.8% increase in stair usage would result in a weight loss and/or weight gain prevention of 300 g/person/year among new stair users. In sum, point‐of‐decision motivational signs may help communities attain Small Step ♯67. However, the singular impact of this community intervention on correcting energy imbalance may be minimal, having slight impact itself on reducing the national obesity prevalence.

Harvie, M.; Howell, A.

doi: 10.1111/j.1467-789X.2006.00207.xpmid: 16436101

Excess adiposity over the pre‐ and postmenopausal years is linked to risk of postmenopausal breast cancer. Weight loss could potentially reduce risk amongst those with excess weight via beneficial effects on the hormonal (decreased circulating levels of oestradiol, testosterone, insulin) and secretory profiles of adipocytes (decreased production of leptin, tumour necrosis factor‐α, interleukin 6 and increased production of adiponectin). Only modest reductions in adipose tissue are achieved and sustained with current weight loss programmes, which makes strategies to mitigate the adverse metabolic effect of adiposity a priority for cancer prevention. The adverse hormonal and secretory effects of adipose tissue are influenced substantially by acute changes in energy balance prior to changes in adiposity. Human and animal studies have shown dietary energy restriction to bring about favourable changes in circulating levels of insulin, leptin, sex hormone binding globulin, insulin‐like growth factor‐1, oestradiol, testosterone, reactive oxygen species, and the production and secretion of locally acting adipokines and inflammatory cytokines, that is, increased adiponectin and decreased interleukin‐6. Achieving and sustaining energy restriction remains a difficult challenge. Intermittent energy restriction is a potential strategy for promoting periods of energy restriction on a long‐term basis. Animal and human data suggest that intermittent energy restriction may have cancer preventative effects beyond that of chronic energy restriction and weight loss. Intermittent energy restriction may be a potential strategy for the primary prevention of breast cancer.

Adam‐Perrot, A.; Clifton, P.; Brouns, F.

doi: 10.1111/j.1467-789X.2006.00222.xpmid: 16436102

Recently, diets low in carbohydrate content have become a matter of international attention because of the WHO recommendations to reduce the overall consumption of sugars and rapidly digestible starches. One of the common metabolic changes assumed to take place when a person follows a low‐carbohydrate diet is ketosis. Low‐carbohydrate intakes result in a reduction of the circulating insulin level, which promotes high level of circulating fatty acids, used for oxidation and production of ketone bodies. It is assumed that when carbohydrate availability is reduced in short term to a significant amount, the body will be stimulated to maximize fat oxidation for energy needs. The currently available scientific literature shows that low‐carbohydrate diets acutely induce a number of favourable effects, such as a rapid weight loss, decrease of fasting glucose and insulin levels, reduction of circulating triglyceride levels and improvement of blood pressure. On the other hand some less desirable immediate effects such as enhanced lean body mass loss, increased urinary calcium loss, increased plasma homocysteine levels, increased low‐density lipoprotein‐cholesterol have been reported. The long‐term effect of the combination of these changes is at present not known. The role of prolonged elevated fat consumption along with low‐carbohydrate diets should be addressed. However, these undesirable effects may be counteracted with consumption of a low‐carbohydrate, high‐protein, low‐fat diet, because this type of diet has been shown to induce favourable effects on feelings of satiety and hunger, help preserve lean body mass, effectively reduce fat mass and beneficially impact on insulin sensitivity and on blood lipid status while supplying sufficient calcium for bone mass maintenance. The latter findings support the need to do more research on this type of hypocaloric low‐carbohydrate diet.

Kovacs, E. M. R.; Mela, D. J.

doi: 10.1111/j.1467-789X.2006.00203.xpmid: 16436103

The scale of the obesity epidemic creates a pressing consumer need as well as an enormous business opportunity for successful development and marketing of food products with added benefits for weight control. A number of proposed functional food ingredients have been shown to act post‐absorptively to influence substrate utilization or thermogenesis. Characteristics and supporting data on conjugated linoleic acid, diglycerides, medium‐chain triglycerides, green tea, ephedrine, caffeine, capsaicin and calcium, are reviewed here, giving examples of how these could act to alter energy expenditure or appetite control. Consideration is also given to other factors, in addition to efficacy, which must be satisfied to get such ingredients into foods. We conclude that, for each of the safe, putatively metabolically active agents, there remain gaps in clinical evidence or knowledge of mechanisms, which need to be addressed in order to specify the dietary conditions and food product compositions where these ingredients could be of most benefit for weight control.

Haaz, S.; Fontaine, K. R.; Cutter, G.; Limdi, N.; Perumean‐Chaney, S.; Allison, D. B.

doi: 10.1111/j.1467-789X.2006.00195.xpmid: 16436104

Obesity is a major health problem facing the developed and developing world. Efforts by individuals, health professionals, educators, and policy makers to combat the escalating trend of growing obesity prevalence have been multifaceted and mixed in outcome. Various dietary supplements have been marketed to reduce obesity. These products have been suggested to accomplish this by decreasing energy intake and energy absorption, and/or increasing metabolic rate. Ephedra, one such supplement, was banned from sale in the US market because of concerns about adverse events. Another substance, Citrus aurantium, which contains several compounds including synephrine alkaloids, has been suggested as a safe alternative. This review examines the evidence for safety and efficacy of C. aurantium and synephrine alkaloids as examined in animal studies, clinical weight loss trials, acute physiologic studies and case reports. Although at least three reviews of C. aurantium have been published, our review expands upon these by: (i) distinguishing and evaluating the efficacy of C. aurantium and related compounds; (ii) including results from previously unreviewed research; (iii) incorporating recent case reports that serve to highlight, in an anecdotal way, potential adverse events related to the use of C. aurantium and related compounds; and (iv) offering recommendations to guide the design of future trials to evaluate the safety and efficacy of C. aurantium. While some evidence is promising, we conclude that larger and more rigorous clinical trials are necessary to draw adequate conclusions regarding the safety and efficacy of C. aurantium and synephrine alkaloids for promoting weight loss.

Powell, D. R.

doi: 10.1111/j.1467-789X.2006.00220.xpmid: 16436105

Sequencing of the human genome has yielded thousands of potential drug targets. The difficulty now is in determining which targets have real therapeutic value and should be the focus of a drug discovery effort. The available evidence suggests that knockout technology can be used prospectively to identify targets that are amenable to drug development for the treatment of a variety of diseases. This review compares the knockout phenotypes of 21 potential obesity targets with the effects of therapeutics designed for those targets on rodents and, when data were available, on humans. The phenotypes of obesity target knockouts model the effects seen when therapeutics designed for those obesity targets are delivered to rodents; of the 21 obesity targets reviewed, 16 showed a correspondence between knockout phenotype and drug effect in mice and/or rats. This suggests that, at least in terms of evaluating obesity targets, it is rare for compensatory developmental changes caused by the gene knockout to prevent detection of the relevant phenotype. In the majority of cases, the knockout phenotypes also modelled the effects seen when the relevant therapeutics were delivered to humans. Thus, it seems rational to use mouse knockout technology prospectively to identify genes that regulate body fat in vivo, and then to develop anti‐obesity therapeutics by targeting the human protein products of these genes. Ultimately, the value of using this approach to identify novel targets for human anti‐obesity therapies will be judged by future studies examining the anti‐obesity effect, in humans, of the therapeutics that result from this approach.

Rössner, Stephan

doi: 10.1111/j.1467-789X.2006.00236.xpmid: 16436106