Skinny people exercise less but eat less


  • Waist circumference is another indicator to diagnose overweight or obesity.
  • It is considered too tall from 80 cm for a woman and 94 cm for a man.

If sport is excellent for health in general, it does not always allow you to lose weight or stay slim… Indeed, according to a study published in the journal Cellular metabolism, people with a lower body mass index (BMI) engage in 23% less physical activity compared to people with a higher BMI. But they ate smaller amounts, 12% fewer calories, than those with a higher BMI.

Overweight after 25

The BMI is an indicator that allows estimating the corpulence of an individual. To calculate it, simply divide your weight in kilograms by your height in centimeters squared. The result of this operation gives a figure that determines in which category the person is located: malnutrition (below 16.5), thinness (from 16.5 to 18.5), normal corpulence (from 18.5 to 25) , overweight (from 25 to 30), moderate obesity (from 30 to 35), severe obesity (from 35 to 40), morbid or massive obesity (over 40).


We expected that these people would be really active and have high activity metabolic rates corresponding to high food intakes.explains John Speakman, one of the study’s authors. It turns out that something very different is going on. They had lower food intake and activity, as well as surprisingly higher-than-expected resting metabolic rates related to elevated thyroid hormone levels“.

Thyroid hormones

The thyroid is a small gland located in the neck that secretes thyroid hormones. These control the rate of chemical functions in the body, i.e. basal metabolism, and affect many vital body functions, such as heart rate or the rate at which calories are burned. .

Normally, when a person exercises regularly, they gain muscle mass. This has an impact on your metabolism which works in a better way. Thus, even at rest, muscle consumes more energy than fat mass and, therefore, the metabolism spends more energy and burns calories.

12% fewer calories

According to scientists, if people stay thin without doing sports, it is because they eat less. To reach this conclusion, the researchers followed two types of people: 173 participants had a normal BMI and 150 had a BMI less than 18.5. For two weeks they recorded their food intake and physical exercise sessions. Thus, they observed that those with a BMI less than 18.5 consumed 12% less food and were 23% less active compared to the others.

energy cost

Although these very thin people had low activity levels, their indicators of heart health, including cholesterol and blood pressure, were very good.explains Sumei Hu, one of the study’s authors. In fact, scientists have observed that people with a BMI below 18.5 have high resting energy expenditure and thyroid activity.

Sport is still essential

In the future, scientists intend to continue their research to better understand the reasons for this phenomenon… And thus, perhaps, be able to find new solutions to help overweight people lose weight.

But the results of this study are not an incentive not to play sports, quite the contrary. To be healthy,World Health Organization (WHO) recommends that adults aged 18 to 64 engage in at least 150 to 300 minutes of moderate-intensity sport or 75 to 150 minutes of vigorous-intensity sport per week.

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