We have known for a few years that 30% of the European population is genetically predisposed to accumulating extra pounds and thereby incur an increased risk of becoming obese. However, the situation of these people is not hopeless because it is possible to counter the action of these genes by adopting good eating habits as well as by increasing the levels of physical activity.

Certain genetic factors play a determining role in the tendency that some people have to fatten easily in an environment where food is abundant, as is currently the case in our society. Two British research teams have shown that people who have certain defective versions of a gene called FTO (for Fat Mass and Obesity) have almost 200% more risk of being obese than those whose gene structure is normal. These defects in the FTO gene are unfortunately very widespread, affecting nearly 30% of the European population, and it goes without saying that the presence of these genes contributes to the phenomenal increase in obesity observed in recent years.

However, people who have a faulty FTO gene are not inevitably destined to become obese. They only run a greater risk of becoming one if they do not pay particular attention to certain aspects of their lifestyle. And among these different factors, we must not overlook the extraordinary impact of regular physical activity.

The risks of gaining weight completely canceled by physical activity

To determine whether a high level of physical activity can reduce the increase in body weight of people with defective versions of the FTO gene, a team of American researchers examined in detail the lifestyle habits of members of an Amish community in Pennsylvania. . These people live in a simple way and apart from modern society, that is to say, they do not use cars or electricity and do all their work manually, without the help of any mechanical machinery.

As a result, it is generally estimated that their level of physical activity is about 6 times greater than that of an average adult. The physical activity levels of 704 members of this community were measured using a device attached to the waist, which recorded their every movement and made it possible to calculate their daily energy expenditure.

In parallel, the collection of blood samples at the beginning of the study made it possible to determine the people who had an altered version of the FTO gene. The results obtained are spectacular: while individuals carrying a defective version of the FTO gene had an increased risk of being obese if their energy expenditure was relatively low, this increased risk was completely canceled out in those who were physically active!

These people showed an additional energy expenditure of about 900 calories per day, which roughly corresponds to 3 to 4 hours of moderate physical activity such as walking, housework or gardening.

Any opportunity to move is good

For individuals whose work requires little energy expenditure (an office job, for example), being physically active for several hours a day can seem difficult.

However, it is possible to modify the routine and create opportunities to move:

– avoid elevators in favor of stairs,

– getting off one (or two) bus or metro stop before your destination or by parking a good distance from the office are all concrete daily actions that can help you improve your level of physical exercise.

Obviously, indulging in more vigorous activities such as brisk walking, jogging, playing tennis or even cross-country skiing several times a week can only increase the positive impact of exercise on body weight, not to mention that being physically active is an extremely effective weapon for the prevention of cardiovascular diseases as well as several types of cancer.


Frayling et al. : A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity Science ; 316: 889-894.

Rampersaud et al. Ann. Intern. Med.

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