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Middlesex University researcher co-authors world’s biggest obesity study

Mariachiara Di Cesare is co-leading author of a major obesity study published in The Lancet involving over 700 scientists across the globe

An obese man (Photo by Tony Alter (Creative Commons 2.0))The world’s largest-ever obesity study was published in The Lancet in April, with the School of Science and Technology’s Mariachiara Di Cesare as co-lead author.

The result of a collaboration between scientists from Imperial College London and 700 researchers from across the globe, the paper concludes that more than one in ten men and one in seven women are now obese.

Overall, the world’s obese population is hitting 640 million.

The study calculated and compared body mass index (BMI) among adult men and women from 1975 to 2014. BMI is a measure of a person’s weight for their height, and indicates whether their weight is healthy.

The data revealed that in four decades global obesity among men has tripled, from 3.2% in 1975 to 10.8%. Obesity among women meanwhile has more than doubled, from 6.4 % in 1975 to 14.9% in 2014.

This translates as 266 million obese men and 375 million obese women in 2014. It also means the world’s population has become heavier by around 1.5kg in each subsequent decade.

In addition, 2.3% of the world’s men, and 5% of the world’s women are now classed as severely obese, which is defined as having a BMI of over 35 kg/m2. This places an individual at significantly increased risk of conditions such as diabetes, heart disease and cancer.

Analysis of the findings showed more obese men and women now live in China and the USA than in any other country. However, the USA still has the highest number of severely obese men and women in the world.

The team predicted if these global trends continue, by 2025 18% of men and 21% of women will be obese. Furthermore, the probability of reaching the World Health Organization global obesity target (which aims for no rise in obesity above 2010 levels by 2025) will be close to zero.

Researchers also examined the number of people who are underweight in different countries. The results revealed levels have decreased from 14% to 9% in men, and 15% to 10% in women.

The percentage of underweight individuals was nonetheless still quite high in countries such as India and Bangladesh, where nearly a quarter of adults are underweight.

The findings also showed that:

  • Japanese men and women had the lowest BMI in the high-income world. Average BMI was higher in English-speaking high-income countries than in non-English speaking high-income countries, with American men and women having the highest BMI of any high-income country
  • The lowest BMIs in Europe were among Swiss women and Bosnian men. Men in the UK had the 10th highest BMI in Europe and women the 3rd highest in Europe. Globally, the UK ranked with the 42nd highest BMI for men and 67th highest for women
  • The country with the highest average BMI was American Samoa (average BMI of 35 kg/m2 for women and 32 kg/m2 for men), where the average individual is classed as obese
  • Morbid obesity, where a person’s weight interferes with basic physical functions such as breathing and walking, now affects around 1% of men and 2% of women. In total, 55 million adults are morbidly obese.

The study was funded by The Wellcome Trust, and Grand Challenges Canada.

Photo: Tony Alter (Creative Commons 2.0)

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