Whether genetically biased for obesity or not – people in industrialized countries have been gaining in weight on average for about three decades. This is evident from a large Norwegian study published in the British Medical Journal. However, those with a genetic predisposition to obesity were the most affected by the increase on average.
The team led by Maria Brandkvist from the Norwegian University of Science and Technology in Trondheim analyzed data from just under 120,000 Norwegians aged 13 to 80 years. The size and weight of different study participants were recorded from 1963 to 2008. The researchers conclude from their results that there is an environment that promotes overweight since the eighties.
Significant increase in the eighties and nineties
The body mass index (BMI) in the normal range is from 18.5 to less than 25. It is calculated from the weight in kilograms divided by the body size squared. Obesity starts at a BMI of 25, obesity at 30.
According to the study, the BMI of Norwegians has gradually increased significantly since 1963. There was a particularly significant increase since the mid-eighties. Before that, the average BMI was still below 25. Then, over the years, he achieved average values in the area of overweight. This development is also in line with WHO estimates that in 2008 64 percent of Norwegians and 51 percent of Norwegians were overweight.
Differences in weight gain
The researchers divided people into five groups – from the largest genetic predisposition for obesity to the lowest. One result: 35-year-old men in their sixties with the highest tendency for obesity had an average of 1.20 higher BMI than men with the lowest. In the zero years, the difference averaged 2.09.
Over the past 40 years, men with a predisposition to obesity have increased significantly more than those without such gene variants. In 35-year-old women, the BMI difference between genetically pre-loaded and unencumbered people increased on average from 1.77 to 2.58.
The significant differences in weight gain between people with and without a tendency to obesity lead the researchers back to an interaction of the environment and the genes.
Global obesity epidemic
Overweight is a worldwide problem. According to the World Health Organization, the rate of obesity worldwide has almost tripled between 1975 and 2016. In 2016, nearly 40 percent of adults were overweight and 13 percent were obese.
"Our study can not answer the causes of the obesity epidemic," says study leader Brandkvist. It would be useful to look back on what life was like in the 1960s, "when it was not so easy or even impossible to opt for such an unhealthy lifestyle," she suggests. "What and how much did we eat then, how did we sleep and how much did we move?"
Too much food, too little exercise
According to her hypothesis, the obesity epidemic is associated with too much food and too little exercise – both are socially conditioned. In addition, poisons and microorganisms could have contributed to this. In a British Medical Journal editorial, US scientists suggest looking more at individual groups of people and better exploring the individual causes of obesity rather than just population-wide strategies.
In addition to a healthy adult diet, the World Health Organization recommends 150 minutes of physical activity per week. In children it should be one hour a day. Employers should offer healthy food and the opportunity to practice sports.