Growing globally, obesity affects nearly 650 million adults, or 13% of the world’s adult population, a percentage that could reach 20% by 2025 if the current rate of progression of this epidemic is sustained. .
“In 40 years, we have gone from a world where underweight was twice as important as obesity to a world where obese people are more numerous than those underweight”, underlines Pr Majid Ezzati, from Imperial College London, which coordinated this study published in the British medical journal The Lancet.
Hailed as one of the most comprehensive to date on the subject, it is based on data from some 19 million people aged 18 and over, living in 186 countries.
By extrapolation, it estimates the number of obese adults at 641 million in 2014, including 375 million women and 266 million men. In 1975, they were only 105 million. An explosion linked in particular to an industrial and too rich diet, but also to genetic predipositions.
According to the World Health Organization (WHO), a person is considered obese when their body mass index (BMI, which is the ratio of weight to height) exceeds 30 kg / m2.
Beyond 35, we talk about severe obesity.
In 40 years, the average BMI has, according to the study, increased from 21.7 to 24.2 in men and from 22.1 to 24.4 in adult women, an increase in weight of 1.5 kg every 10 years on average.
“If the progression of obesity continues at the same rate, by 2025 about a fifth of men (18%) and women (21%) will be obese in the world while 6% of men and 9% of women will be affected. of severe obesity “, warn the authors.
The percentage of obese people tripled among men, from 3.2% in 1975 to 10.8% in 2014, and more than doubled among women (from 6.4% to 14.9%), with disparities very important depending on the country.
Obesity is now “a major public health problem” in many middle-income regions (Pacific, Middle East, North Africa, some states in South America or the Caribbean), notes the study.
While the BMI remained broadly stable between 1975 and 2014 among Japanese women and most European women (with the notable exception of the British), the six rich English-speaking countries (USA, UK, Australia, Canada, Ireland and New Zealand) present much more worrying results: they are now home to a fifth of obese adults in the world, or 118 million people, and 27% of severely obese, or 50 million.
However, the prize goes to Polynesia and Micronesia, Pacific islands where 38% of men and half of adult women are obese. In American Samoa, an island in the South Pacific, the average BMI today peaks at 34.8 for women and 32.2 for adult men, compared to 28 in the United States.
If policies to fight against obesity are not implemented “quickly” in the world, “health consequences of unknown magnitude” are to be feared, Professor Ezzati told AFP.
Conversely, being underweight – or underweight – (BMI less than 18.5) linked to malnutrition remains a major problem in other regions of the world, such as South Asia or certain states of Africa.
According to the study, nearly a quarter of the population was underweight in South Asia in 2014, compared to 12% to 15% of the population in Central and East Africa.
Timor-Lest (official name for East Timor), Ethiopia and Eritrea had the lowest average BMIs in the world in 2014, at around 20.
Underweight is blamed for increased mortality in women and very young children before and after childbirth, and increases the risk of death from infectious diseases such as tuberculosis. Obesity promotes certain cancers and cardiovascular diseases.