In industrialized societies, less calories are burned, but not enough to justify the obesity rates observed. It matters more what we eat.
One in 8 people in the world is suffering from obesity, with the rates of this condition doubled, among adults, in the last 35 years. At the origin of the pathological and chronic weight excess, which affects the overall state of health, there is an imbalance between the energy taken through nutrition and that expenditure with physical activity.
But which factor does it count more? A wrong diet or too sedentary life? Based on a research published on Proceedings of the National Academy of Sciencesincorrect nutrition has a more important role, in the world epidemic of obesity, compared to the lack of movement.
Less calories burned, but that’s not enough
A group of scientists from Duke University of Durham (United States) concluded that, if it is true that in industrialized societies they burn less calories, this lower energy expenditure It is not low enough to justify the marked increase in obesity: only in Italy, 4 out of 10 adults are obese or overweight. The obesity would then be more connected to food choices and the consumption of excessively caloric food.
The study, however, raised some criticisms about the method of analysis chosen, as well as not clarifying the exact origins of the epidemic. Given that the type of feeding is really the main culprit, how is it now a common belief, what types of foods or which food habits are most responsible for obesity?
Energy expenditure compared
Scientists extracted from a database containing the data on thousands of people of all continents the data on the energy expenditure of 34 populations with a different level of economic development and with different lifestyles. The energy expenditure had been calculated cOn the double -marked water methodin which, that is, the atoms of hydrogen and oxygen were both partially replaced with uncommon isotopes of these elements, so as to use them as tracents while the drunk water transits inside the body.
When we burn calories, oxygen atoms in the water we drink are used to form the CO2 we enhance. Thus measuring the excess of heavy hydrogen in the urine of a person a few days later you can estimate how much, of the oxygen entered, it was transformed into CO2, and how much energy has been burned.
The researchers then calculated how much, of this energy expenditure, He had left for the basal functionshow to breathe or regulate body temperature, and how much it was linked to physical activity. When they adequate the parameters of energy expenditure found in factors such as age and body size they observed – as expected – that In the most economically advanced companies, the total energy expenditure is less.
For example, a rural community of Siberia, the Tuvan, burns more calories than the average person of the United States.
Too much food, little expenditure
According to the researchers, however, the differences also between industrialized societies and are not minimal and vary very much: more likely they are linked to differences in the energies spent for the basal metabolism instead of for the calories burned with physical activity. Past studies have in fact hypothesized that in rural societies we burn more to keep the immune functions active and vigilant because they are exposed to more pathogens.
In conclusion, the differences in the energy expenditure they would just explain 10% of the relationship between obesity and economic development. The remaining 90% must therefore depend on food.
Ok, but what food?
Since the study did not collect data on the participants’ diet, It is not clear which elements of the food of industrialized companies are under accusationeven if an excess of body fat has been observed in the most inclined populations to consume ultra -prompt foods, excessively rich in calories.
The authors of the research also specify that what found in any way does not want to diminish the importance of physical activity, fundamental for health in general, as well as for the control of body weight.
Among the criticisms moved to work, on the other hand, there are only a few dozen people from rural companies or hunters-cackers, and having taken in a rather arbitrary way that the energy spent for the basic metabolic functions can be extrapolated from that total burnt in the various populations.
