PARIS, Nov 28 — Being overweight or obese count among the risk factors associated with many chronic diseases, but one study reveals that they may play a role in the development of 17 types of cancer, starting as soon as the end of adolescence.

Carried out exclusively on men, this research underlines the importance of taking new action to combat sedentary lifestyles, at a time when obesity is on the increase worldwide.

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“Almost two thirds of adults and 1 in 3 children in the WHO European Region are living with overweight or obesity, and these rates are still growing,” warned the World Health Organisation (WHO) in a report released in 2022.

The global health authority goes as far as to warn that “obesity might overtake smoking as the main risk for preventable cancer” in the coming decades, and estimates the condition to be a cause of 13 different types of cancer.

It’s a major public health problem that the WHO is aiming to prevent by “creating healthy environments.”

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This involves fighting sedentary lifestyles, particularly linked to the use of screen-based devices, as well as promoting healthy, balanced diets and increasing physical activity.

A new study by researchers at Sweden’s University of Gothenburg highlights the role of obesity, and more generally of a high body mass index (BMI), on health, and in particular on the risk of cancer.

The analysis involved no fewer than 1.4 million men who took the conscription examination between 1968 and 2005, when they were aged between 16 and 25, nearly 80,000 of whom went on to develop cancer during an average follow-up period of 31 years.

Published in the journal Obesity, this research suggests that a high BMI at age 18, ie, in late adolescence, is linked to an increased risk of several types of cancer in adulthood, more so than having poor fitness at the same age.

“Overweight and obesity at a young age seems to increase the risk of developing cancer, and we see links between unhealthy weight and cancer in almost every organ.

Given the alarming trend of obesity in childhood and adolescence, this study reinforces the need to deploy strong resources to reverse this trend,” explains the first author of the research, Aron Onerup, of the University of Gothenburg, quoted in a news release.

In the course of these investigations, researchers observed a higher risk of cancer of the lung, head, neck, brain, thyroid, oesophagus, stomach, pancreas, liver, colon, rectum, kidney and bladder, as well as melanoma, leukemia, myeloma and lymphoma in participants with a high BMI at the average age of 18.

Note that a BMI greater than 25 was considered high — including the overweight and obese categories.

Three to four times higher cancer risk

The researchers point out that this association was even stronger for cancers of the oesophagus, stomach and kidney, reporting a risk three to four times higher for obese men at the age of 18.

It should be noted, however, that a BMI considered normal — ie, between 20 and 22.4 — was also associated with an elevated risk of cancers of the head, neck, oesophagus, stomach, pancreas, liver, kidney, melanoma and non-Hodgkin’s lymphoma.

This astonishing finding may suggest that “the current definition of normal weight may be applicable primarily for older adults, while an optimal weight as a young adult is likely to be in a lower range,” says senior author, Maria Åberg.

As for prostate cancer, the risk was higher in participants who were neither overweight nor obese at the time of enlistment.

“In 30 years, the researchers expect an increase in the proportion of cancer cases linked to youth overweight and obesity, calculated based on overweight and obesity in today’s 18-year-old men in Sweden.

For cancer of the stomach, the proportion rises to 32 per cent and for cancer of the oesophagus to 37 per cent.

Based on the current prevalence of youth overweight and obesity in the United States, more than one in two cases of these two cancers could be linked to high BMI in the late teenage years in 30 years,” the research concludes. — ETX Studio