Submitted by Administrator on Fri, 15/07/2016 - 10:19
A study of 3.9 million adults published this week in The Lancet finds that being overweight or obese is associated with an increased risk of premature death. The risks of coronary heart disease, stroke, respiratory disease and cancer are all increased. Overall, the excess risk of premature death (before age 70) among those who are overweight or obese is about three times as great in men as in women.
WHO estimates that 1.3 billion adults worldwide are overweight, and that a further 600 million are obese. The prevalence of adult obesity is 20% in Europe and 31% in North America. WHO uses body-mass index (BMI) to relate weight to height, and defines BMI 18.5-25 as normal, 25-30 as overweight, 30-35 as moderately obese, and over 40 as severely obese.
“On average, overweight people lose about one year of life expectancy, and moderately obese people lose about three years of life expectancy” says Dr Emanuele Di Angelantonio, the lead author from the University of Cambridge.
“We also found that men who were obese were at much higher risk of premature death than obese women. This is consistent with previous observations that obese men have greater insulin resistance, liver fat levels, and diabetes risk than women.”
The risk risk of premature death increased steadily and steeply as BMI increased. A similar trend was seen in many parts of the world and for all four main causes of death.
Where the risk of death before age 70 would be 19% and 11% for men and women with a normal BMI, the study found that it would be 29.5% and 14.6% for moderately obese men and women. This corresponds to an absolute increase of 10.5% for men, and 3.6% for women.
The new study brings together information on the causes of any deaths in 3.9 million adults (69% women) from 189 previous studies in Europe, North America and elsewhere. At entry to the study all were aged between 20 and 90 years old, and were non-smokers who were not known to have any chronic disease when their BMI was recorded. The analysis is of those who then survived at least another five years.
The study also estimated the reduction in deaths in a population that would occur if a risk factor were eliminated. The authors say that assuming that the associations between high BMI and mortality are largely causal - if those who were overweight or obese had WHO-defined normal levels of BMI, the proportion of premature deaths that would be avoided would be about one in 7 in Europe and one in 5 in North America.
The authors note that one important limitation is that their only measure of obesity was BMI, which does not assess fat distribution in different parts of the body, muscle mass, or obesity-related metabolic factors such as blood sugar or cholesterol.
The Lancet publication can be read here.
