14 DAY TRIAL // Most people take obesity as a consequence of a sedentary life, when in fact multiple studies carried out in the last two decades clearly show that the couch potato lifestyle can be blamed on overeating which is probably the most likely cause for the world's obesity epidemic. What most people don't understand it that obesity is triggered by an imbalance in the body's energy management. The energy that is received by the body through food and that is not entirely consumed is deposited in the living tissue in the form of excess fat.
Such imbalances are determined either by overeating or sedentariness but most often by both. According to studies, daily physical activity has been steadily decreasing in the last decades, although the caloric intake remained roughly the same. Most of these studies have been based on self-reported data, which at times can be highly inaccurate.
In order to get more accurate data, Klaas Westerterp from the Maastricht University and John Speakman from the University of Aberdeen initiated their own study using the so-called double labeled water method, in which for a period of two weeks the participants were given water molecules that contained hydrogen and oxygen atoms with an excess of neutrons. This water could then be traced into the urine of the participants and could be used to calculate the metabolism of a person.
A comparison between all the previous studies and the results of the double labeled water investigations conducted throughout the last two decades revealed that people were consuming roughly the same amounts of calories as always, regardless of the countries they were living in, meaning that daily activity was not at fault. Additionally, the number of obese people doubled in the Netherlands in the last twenty years, while in the US the number tripled.
"We're not saying that exercise doesn't make a difference. If you train for marathons, then of course you'll get fitter. But for average people, the daily physical activity hasn't changed. In the time we spend watching television today, people probably listened to radio in the 1950s and read books in the 1920s. This work suggests that the obesity epidemic has been largely driven by increases in food intake.", says Speakman.
"The study is provocative. But I wouldn't hang my hat on it", says Loren Cordain, physiologist at Colorado State University. He believes that studies using the double labeled water technique experimented with different procedures and that a low number of participants are not representative for a whole country.