When I started working as part of a global consortium investigating non-communicable disease risk factors, I already knew obesity levels were dangerously high, but the scenario revealed in our new paper was beyond my worst prediction.
The paper, ‘Trends in adult body-mass index (BMI) in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19.2 million participants‘, has been possible thanks to the effort of over 700 health scientists around the world, who have enthusiastically embarked on the challenge of producing rigorous estimations for every country over the past 39 years.
Tackling the obesity epidemic is increasingly a priority for national and local governments and in autumn last year the UK’s Chief Medical Officer argued for including obesity in the national risk planning. Is the alarmism real?
Obesity alone has been estimated to have caused almost 4.5 million deaths worldwide in 2013 (8.1 per cent of the total) and it is directly associated with cardiovascular diseases, multiple cancers (oesophagus, colon and rectum, among others), and diabetes. Moreover, obesity ranks first among women and second among men as a risk factor associated with disability adjusted life-years (the lost years of healthy life i.e. because of living with a disease or because of premature death). Apart from these serious risks to health, recent estimations suggest an overall economic cost of roughly $2 trillion globally.
The Lancet study provides an overall picture of more than 640 million adult people obese (body mass index equal to or greater than 30 kg/m2) in 2014, corresponding to 14 adults out every 100. This is just a global average and unfortunately the scenario is worse in many individual countries.
The first ten countries with the highest prevalence of obese adults, both men and women, are part of Oceania, with the prevalence of obesity reaching 49 per cent among men in French Polynesia and the Cook Islands and over 57 per cent among women in American Samoa and the Cook Islands. At the opposite end of the rankings are Timor-Leste and Japan, with a prevalence of obese women below three per cent, and Burundi and Timor-Leste with prevalences below one per cent for men. The interesting fact is that nowhere in the world between 1975 and 2014 did we observe a halt in the prevalence of obesity: the trend is positive (or should we say “negative”?) everywhere.
Tackling this issue is extremely complex but action is required from both individuals and governments.
The size of the population is not a minor component here. For example, in China and the USA, 46 million women and 42-43 million men are obese; however the prevalence of obesity among women and men is “only” 8.2 per cent and 7.4 per cent in the former and 33.6 per cent and 34.9 per cent in the latter.
Conversely, alongside the obesity debate, the research reveals that some populations are still malnourished. While the decline in the prevalence of people who are underweight (body mass index below 18.5 kg/m2) is decreasing, rates are still high in some south Asian countries like Bangladesh and India, with an underweight prevalence of 26.5 per cent and 24.9 per cent among women and 24.5 per cent and 23.1 per cent among men.
The good news is that we can reverse obesity trends with concerted action. We need to push for better, easier and cheaper access to healthy food; reduce consumption of unhealthy food (e.g. sugar) through taxation; support and incentivise physical activity; and invest in health education from primary school age. And we need to seriously challenge lifestyle choices of diet and leading sedentary lives. Tackling this issue is extremely complex but action is required from both individuals and governments.