Sometimes active people gain more weight than couch potatoes – here's why

Governments are always telling us to eat less and exercise more to be healthier, but this is an obvious problem. Being active is likely to make you hungry, so you risk eating more to make up for and gaining more weight than if you had never left the couch.

Dietitians dream of the day when they can design diets for people where they are more active but not hungry at the same time. Unfortunately, it's more complicated than you think: we're still looking for the mechanism that governs how the energy spent translates into our level of appetite. And as we will see, this is by no means the only thing that complicates things.

In an ideal world, the human body would be wired to immediately detect changes in the amount of energy we consume, then give us the appetite to eat the necessary amount. Alas no: we are all hungry two or three times a day, sometimes more, no matter what we are getting ready for. Our body also emits much stronger signals about our appetite when we are not eating enough than when we have eaten too much. This poor relationship with daily comments helps explain why obese people still experience a strong sense of hunger – and all the cheap foods that are high in calories and widely available, of course.

Mysteries of appetite

There are many things we do not understand about the effect of increased activity. Most of us burn different amounts of calories on different days – gym followers have days off, while everyone has days when they walk in more stores, do more housework or other.

Studies do not establish a clear relationship between these variations and the amount of food an average person consumes on the day in question. But it's not easy either to say anything definitive. Most research has focused on aerobic exercise and has shown, for example, that while some highly trained and lean people tend to eat enough to compensate for extra calories burned, overweight people are more likely to eat too much.

What could be hiding behind this difference? One possibility is that physiological processes change in people who do more exercise – for example, their intestinal hormones can be released at different concentrations when they eat, which can affect the amount of food they have need.

A long-standing issue, going back about 60 years, is knowing where the metabolism is in the image. Some important work published in 2013 by a Leeds team revealed that overweight people were more hungry and consumed more calories than thinner people. Since overweight people have a higher resting metabolic rate – the rate at which the body burns energy at rest – the group suggested that there was a correlation between this rate and the size of the body. meals that people eat. The fact that people's resting metabolic rates are stable, regardless of the fluctuations in daily exercise, may explain why physical activity levels often have no effect on the amount of food we eat on the same day.

Yet this does not mean that the resting metabolic rate actually determines the amount of food we eat. The team proposed that a person's body composition, particularly its amount of muscle mbad, could regulate its metabolic rate. If this is the case, the metabolic rate could be only an intermediary – conveying information about body composition through hypothalamic networks in the brain, supposed to control appetite. Whatever the case may be, it still requires additional research.

Our study

To examine what is happening in real life rather than in the laboratory environment, I have co-authored a new study on the evolution of caloric intake of people on days when they are more active without deliberately taking exercise. from the visit to the dentist at the beach day with the children. We examined 242 people – 114 men and 128 women. We found that their volume of activity affected their consumption, but that their resting metabolic rates also influenced their appetite – that is, overweight people tended to eat more.

This is another step forward in understanding the relationship between activity and the calories we consume. But do not expect this to translate into a magic formula to optimize each person's relationship with activity and food in the future. Many variables have hardly been taken into account by researchers. For example, most of the work has focused on white men between the ages of 20 and 30 years old. Yet, it is obvious that women are more inclined to compensate for extra physical activity by eating.

Similarly, different genetic characteristics are likely to be important – some people are more agitated, for example. Then there are differences in people's psychology and how much they use food as a reward. People who have lost or gained weight will have different appetite signals for people whose weight is stable. The moment of activity during the day is also likely to make a difference.

I doubt that in my lifetime we will reach such a point that we will be able to examine the genetic constitution of any person and tell them exactly what will work for them. From our study, we can say that many people are likely to eat more when they are more active. Simply moving more will not lead to spontaneous weight loss – people should be aware of it and watch how much food they eat.