January 13, 2009 – Weight loss is generally associated with a judicious combination of dietary restriction and exercise. It is even thought that our sedentary lifestyle is one of the causes of the increase in obesity in modern societies. However, to the surprise of American researchers, physical inactivity would not be to blame.
The researchers compared the diet of 172 African-American women who weighed an average of 84 pounds to 149 African women from Niger with an average weight of 58 pounds. They wanted to show that the difference in weight between these two groups of women with comparable genetic background (African descent) was due to their different levels of physical activity. They assumed that Nigerian women exert themselves more physically than Americans.
However, the results showed that there was little difference between the energy expenditure linked to physical activity of Nigerian women and that of American women. The level of physical activity was also not associated with the formation of adipose tissue (fat stores). Researchers conclude that physical expenditure may play a minor role in preventing excess weight.
The authors of the study hypothesize that eating habits are more likely to explain the difference in weight between African Americans and African women, although they have not collected any data on this subject. The Nigerien diet consists mainly of plants, mainly fibers and carbohydrates. The American diet is rather rich in animal products, fats and industrial foods.
These results could, however, refocus the problem of obesity on diet and relativize the role of exercise in prevention, they believe.
For Quebec researcher Angelo Tremblay, an obesity specialist, these results are not surprising: “We have already shown that only intense and vigorous exercise results in a negative caloric balance,” he says. Moderate physical activity, even when it causes more energy expenditure than very vigorous exercise, does not result in a loss of calories high enough to lose weight. “However, the authors of this study did not take into account the intensity of physical activity”, underlines the researcher who holds the Canada Research Chair in physical activity, nutrition and energy balance at the University. Laval. He also recalls that, whatever the exercise program adopted, it is first of all important to modify your diet if you hope to lose weight.
Pierre Lefrançois – PasseportSanté.net
According to e! Science News.
1. Ebersole KE, Dugas LR, et al. Energy Expenditure and Adiposity in Nigerian and African-American Women. Obesity (Silver Spring). 2008, 16, 2148–2154.
