A triple jump since 1975 in the percentage of adults all over the world who are overweight is primarily driven by a shift in diet and lack of exercise, but genes also play a role, according to a major study published Thursday.
For people genetically exposed to a wider spread, these unhealthy lifestyle aggravated the problem, resulting in an even higher weight gain, researchers reported in BMJ a peer-reviewed medical journal. [1
A BMI of 25 up to 30 means being overweight. Thirteen and above correspond to obesity, a major risk factor for heart attack, stroke, diabetes and certain cancers.
About four percent of adults in the mid-1970s had a BMI of 30 or higher. In 2016, this proportion had increased to 13 percent (11 for men and 15 for women), according to the World Health Organization.
There are currently about two billion people 18 and older-39 percent of all adults – with the BMI above the "overweight" threshold of 25 and 700 million of them, are clinically overweight.
The prevalence of overweight has increased even more dramatically among children, from four percent in 1975 to over 18 percent in 2016.
To discuss the relative impact of environment and nuisance on obesity, researchers led by Maria Brandkvist at the Norwegian Science University using data on nearly 120,000 people in Norway, whose height and weight were measured regularly between 1963 and 2008.
Adults began to tip the scales at significantly higher weights in the 1980s and 1990s. they found.
The births after 1970 were much more likely to have a significantly higher BMI than young adults than previous generations.
& # 39; Obese & # 39; Environment
Half of the monitored people were divided into five groups depending on their genetic susceptibility to obesity.
For example, comparing the two groups at the extremes, the researchers found that 35-year-old men with genetic variants known to favor weight gain were already heavier in the mid-1960s than men of the same age without the fat-inducing genes. .
Four decades later – although the obesity rate rose across the board – this hole almost doubled.
Women showed the same trend, although the increase over time was somewhat less.
"Genetic predisposition would make a 35-year-old man with an average height 3.9 kilos heavier than his genetically protected peers in the 1960s," Brandkvist explained.
"In Norway today his vulnerable genes would make him more than 6.8 kg heavier."
In addition, he has been given an additional 7.1 kilos "simply because of living in our" obese "environment," she added.
"This man's 13.9 kg excess weight is mostly due to today's unhealthy lifestyle, but also to how his genes interact with the environment."
While the link between the genetic profiles and the fat content was strong, the study – by its nature – do not determine a direct relationship between effect and effect, the authors are cautious.
Only clinical trials can highlight causal relationships, but for many areas of interest, such experiments are not possible for humans for both practical and ethical reasons.
Significant increase in body weight since the 1960s due to interaction between genes and environment
© 2019 AFP
Genes, yes, but obesity pandemic mainly down to diet: study (2019, July 4)
July 4, 2019
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