NEWS & VIEWS OBESITY

Global trends in the prevalence of overweight and obesity Camilla Schmidt Morgen and Thorkild I. A. Sørensen

A new report provides compelling evidence of the high prevalence of overweight and obesity throughout the world. The prevalence has increased since 1980, but at different rates across ages, times and locations. Studies exploring the causes of these differences could aid development of effective prevention strategies. Morgen, C. S. & Sørensen, T. I. A. Nat. Rev. Endocrinol. 10, 513–514 (2014); published online 22 July 2014; doi:10.1038/nrendo.2014.124

adolescents and young adults has plateau­ed in several European countries, in the USA and in Australia.3 Further­more, the increase in overweight and obesity has recently been shown to have levelled off in adults (aged 20–59 years) in the USA,4 but a consistent pattern of stability has not been found worldwide. The new study by Ng and colleagues provides a very useful overview of the global trends in the prevalence of overweight and obesity, as well as current levels. The study also confirmed the levelling off in the increase since 2000 in developing countries. This finding deserves particular attention, both for offering leads to cope with the current high prevalence of overweight and obesity and for estimating trajectories for future changes. A levelling off following a rise in prevalence has been observed before. In Denmark, the obesity epidemic among children and young men has developed in alternating phases of increasing and stable prevalence; it was low and stable in the birth cohorts from the 1920s through to the early 1940s, rose several-fold until the early 1950s and then was again stable until a steep increase started in the early 1970s.5 A critical question is whether the levelling off during the past decade found by Ng et al. is transient and might be followed by a new rise or if it represents a real turn-around in the course of the epidemic. The latter possibility is supported by the finding of a declining prevalence in some developed countries and some segments of the populations.6 Overweight and obesity are the result of a cumulative positive energy balance that is often tiny on an average day-to-day basis and develops over

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many years. In addition, the positive energy balance is associated with a concomitantly increased energy demand owing to an increase in the amount of metabolically active lean mass. General availability of food that makes it possible to meet this increased energy demand is obviously a prerequi­site for the development of overweight and eventual obesity. Establishing a negative energy balance in these individuals should reduce the pro­blem of overweight and prevent the development of obesity, but this principle has so far failed to provide a feasible and sustainable solution. The development of overweight and obesity is a multifactorial, very complex process;7,8 however, a crucial task is to search for what reversible factors under­lie these conditions at both the individual and population levels. A thorough investiga­tion of what factors changed before the increase in prevalence and therefore could have been drivers of the obesity epidemic might be a fruitful approach for developing new strategie­s to tackle the epidemic. Overweight and obesity are strongly influe­nced by genetics, but the epidemic of these conditions must have been induced by some sort of change in the environment, which possibly interacts with the genetic Vita liy Pa

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The Lancet recently published a comprehensive and systematic analysis of the global, regional and national prevalence of overweight and obesity in the period from 1980 to 2013.1 Data from 188 countries were used to estimate the prevalence of overweight and obesity by sex, age, year and country. Ng and colleagues found a large increase in the preva­lence of overweight and obesity over the study period, which has resulted in a very high current prevalence in both developed and developing countries. In developed countries, the prevalence of overweight (BMI ≥25 kg/m2) and obesity (BMI ≥30 kg/m 2) among men rose from 28.8% in 1980 to 36.9% in 2013. Among women, the prevalence rose from 29.8% to 38.0% over the same period. Among boys in developed countries, the prevalence rose from 16.9% to 23.8%, and among girls it rose from 16.2% to 22.6%. A rise, although slower and at a lower level, was also seen for children, adolescents and adults in developing countries (8.1% to 12.9%). The prevalence of obesity was found to be about one-third that of overweight, but showed the same pattern of increase. In view of the association of overweight and obesity with both short-term and long-term adverse somatic, psychosocial and socioeconomic conditions, these findings confirm the claim by the WHO that overweight and obesity constitute one of the most important threats to global public health today.2 Many previous studies have reported an increasing prevalence of overweight and obes­ity in developed countries since the 1970s. The prevalence continues to rise in many countries around the world, but within the past decade the prevalence of over­weight and obesity among children,

VOLUME 10  |  SEPTEMBER 2014  |  513 © 2014 Macmillan Publishers Limited. All rights reserved

NEWS & VIEWS factors. Ng and colleagues mention excess calorie intake, altered food composition and physical inactivity, promoted by the so-called obesogenic environment, as probable drivers of the epidemic. However, the diversity and patterns of the epidemic strongly suggest that other driving factors are involved. In addition to changes in the gut microbiota, mentioned by Ng and co-workers, numerous candidate drivers have been proposed.9 A potentially very important factor is worsen­ ing of some aspects of the psychosocial environ­ment over the study period, which is a strong predictor of the development of overweight and obesity and might create a vicious cycle as adverse psychosocial conditions are also probable consequences of obesity.10 A major challenge is to find out whether these factors, as well as several others that make up the apparent obesogenic environment, really are causes of the development of overweight and obesity and would thus be suitable targets for intervention. Most of the environmental factors thought to be involved in the development of overweight and obesity are presumed to oper­ ate continuously and have an immediate effect on fat deposition. However, changes in environ­mental exposures early in life— before, during or after pregnancy—that have a sustained long-term effect on the predisposition to develop overweight and obesity are of particular interest as possible drivers of the epidemic. The distinct alternating phases of the epidemic, which are linked to birth cohorts and are detectable in cohorts before they reach school age, strongly suggest that such factors have been drivers of the epidemic in Denmark.5 This possibility might be worth pursuing on a global scale, as early life factors could be a target for preventive actions that are generally accessible and well accepted by parents, who are presumably highly motivated to optimize their child’s future health. The seriousness of the problem is illus­ trated by the estimation by Ng and col­lea­ gues that there are 671 million individuals with obesity in the world, of whom 62% live in developing countries. The stabilization and even decline in prevalence in some countries raises expectations that a solution might be found. Ng and co-workers emphasize that they have found no national success stories and highlight the need for “urgent global action and leadership … to help countries to more effectively intervene”. However, what strategies to use and how to implement them efficiently remain un­answered questions. 514  |  SEPTEMBER 2014  |  VOLUME 10

Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospitals, The Capital Region, Nordre Fasanvej 57, DK2000 Frederiksberg, Copenhagen, Denmark (C.S.M.). The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 1, DK2100 Copenhagen, Denmark (T.I.A.S.). Correspondence to: T.I.A.S. [email protected] Competing interests The authors declare no competing interests. 1.

Ng, M. et al. Global, regional, and national prevalence of overweight and obesity in children and adults during 1980–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet http:// dx.doi.org/10.1016/S0140-6736(14) 60460-8. 2. WHO. Global status report on noncommunicable diseases 2010 [online], http:// www.who.int/nmh/publications/ncd_report_ full_en.pdf (2010). 3. Rokholm, B., Baker, J. L. & Sørensen, T. I. A. The levelling off of the obesity epidemic since the year 1999—a review of evidence and

perspectives. Obesity Rev. 11, 835–846 (2010). 4. Ogden, C. L., Carroll, M. D., Kit, B. K. & Flegal, K. M. Prevalence of childhood and adult obesity in the United States, 2011–2012. JAMA 311, 806–814 (2014). 5. Olsen, L. W., Baker, J. L., Holst, C. & Sørensen, T. I. Birth cohort effect on the obesity epidemic in Denmark. Epidemiology 17, 292–295 (2006). 6. de Wilde, J. A., Verkerk, P. H. & Middelkoop, B. J. Declining and stabilising trends in prevalence of overweight and obesity in Dutch, Turkish, Moroccan and South Asian children 3–16 years of age between 1999 and 2011 in the Netherlands. Arch. Dis. Child. 99, 46–51 (2014). 7. Speakman, J. R. Evolutionary perspectives on the obesity epidemic: adaptive, maladaptive, and neutral viewpoints. Annu. Rev. Nutr. 33, 289–317 (2013). 8. Shook, R. P., Hand, G. A. & Blair, S. N. Top 10 research questions related to energy balance. Res. Q Exerc. Sport 85, 49–58 (2014). 9. McAllister, E. J. et al. Ten putative contributors to the obesity epidemic. Crit. Rev. Food Sci. Nutr. 49, 868–913 (2009). 10. Stunkard, A. J. & Sørensen, T. I. Obesity and socioeconomic status—a complex relation. N. Engl. J. Med. 329, 1036–1037 (1993).

DIABETES

Safety and efficacy of albiglutide —results from two trials Giuseppe Derosa and Pamela Maffioli

Type 2 diabetes mellitus is associated with a poor quality of life and considerable health-care costs and can be difficult to control. The recent results from the HARMONY 3 and HARMONY 6 trials suggest that albiglutide is a safe and effective treatment option for patients with type 2 diabetes mellitus. Derosa, G. & Maffioli, P. Nat. Rev. Endocrinol. 10, 514–516 (2014); published online 29 July 2014; doi:10.1038/nrendo.2014.126

Type 2 diabetes mellitus (T2DM) is a progressive disease characterized by worsening function of the pancreatic islet cells and increasing insulin resistance, which lead to dis­e ase progression and cause glycaemic con­trol to worsen over time.1 Initial antihyperglycaemic monotherapy often does not achieve adequate glycaemic control in patients with T2DM; 1 despite advances in the available treatments, nearly 50% of patients with this condition do not meet their glycaemic target. 2 For this reason, combination therapy has emerged as an alternative approach, which could help more patients achieve their target HbA 1c level soon after treatment is started and avoid or delay the need for subsequent changes to the treatment regimen to m­a intain glycaem­ic targets.3



Incretin-based therapies have been devel­oped in the past few years and are now widely used in clinical practice. This class of drugs includes both the dipeptidyl p­eptidase‑4 (DPP‑4) inhibitors (sitaglip­tin, vilda­glip­tin, saxagliptin and linagliptin) and the glucagon-like peptide 1 (GLP‑1) receptor agonists (exenatide, exenatide long act­ing release, liraglutide and lixisenatide). Given the efficacy and safety of these drugs,4,5 new molecules have been developed, such as alogliptin (a new DPP‑4 inhibitor) and albiglutide (a long-acting GLP‑1 receptor ago­nist). Albiglutide is of particular interest; it is com­p osed of a DPP‑4 resistant GLP‑1 dimer fused to recombinant human albumin, which extends the half-life of the drug to ~5 days and thus enables onceweekly dosing. The HARMONY program www.nature.com/nrendo

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Obesity: global trends in the prevalence of overweight and obesity.

A new report provides compelling evidence of the high prevalence of overweight and obesity throughout the world. The prevalence has increased since 19...
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