Over a third of people in UK and US will be obese by 2025

By Kate Bass, B.Sc.Apr 1 2016

A recent analysis of body mass index (BMI) around the world has revealed a startling increase in the prevalence of obesity. The number of obese people worldwide increased from 105 million in 1975 to 641 million in 2014.

If the increases continue at this rate, over 30% of UK men and women, and over 40% of US men and women will be obese by 2025. Globally, about a fifth of adults will be obese by 2025.

Body mass index is a simple means for approximating the proportion of body tissue to height, and gives an indication of whether an individual is carrying too much (or too little) weight. For adults, a BMI of 18.5 to 25.0 is considered to be within the healthy range. Obesity is defined as a BMI above 30.

It has long been known that having a high BMI increases the risk of a range of chronic, life-threatening conditions such as cardiovascular disease, kidney diseases, diabetes, and even some cancers. In view of this and the recent increases in the proportion of people who are obese, a global target to achieve 2010 obesity levels by 2025 was agreed.

In order to assess whether this target was likely to be met, the NCD Risk Factor Collaboration analyzed adult BMI measurements for 9.9 million men and 9.3 million women between 1975 and 2014.

The research showed that the proportion of obese men has more than tripled and the proportion of obese women has more than doubled since 1975. Average BMI has increased by 11.5% in men and 10.4% in women.

This is equivalent to the population becoming an average of 1.5 kg heavier every 10 years. Should increases in obesity continue at this rate, around a fifth of the population will be obese by 2025.

Thus, based on current trends, the world will not meet the global obesity target by 2025. Furthermore, not only will we fail to meet the target but the proportion of women with severe obesity will be greater than that of underweight (BMI<18.5) women.

Interestingly, no increase in average BMI over the 40 years was observed for women in Singapore, Japan, and a few European countries including Czech Republic, Belgium, France, and Switzerland. At the other end of the scale, more than a quarter of severely obese men and almost a fifth of severely obese women in the world live in the USA.

We should also remember that, despite overall increases in bodyweight globally, there are still regions of the world where excessively low body weight remains a serious public health. In south Asia, for example, almost a quarter of the population are still underweight and in Ethiopia the men have an average BMI of only 20.1.

Over the past 40 years, we have changed from a world in which underweight prevalence was more than double that of obesity, to one in which more people are obese than underweight.”

Professor Majid Ezzati from the School of Public Health at Imperial College London, London, UK.