Can Junk Food Make You Lazy?
Do people who are tired and sedentary become overweight or do people who are overweight become tired and sedentary? That was the question a team from UCLA set out to explore when they placed rats on one of two diets for six months. One diet was highly processed and included substantially more sugar – a proxy for a junk food diet. The other diet consisted of a standard (relatively unprocessed) rat chow. All the rats were given a task (pressing a lever to receive a reward of food or water). After three months, the rats consuming the junk food diet were significantly heavier and took breaks that were nearly twice as long in between tasks as the leaner rats fed the standard chow. The final phase of the study involved switching the rats to the opposite diet for a seven-day period to simulate a dietary binge. No changes were observed either in weight or motivation on the lever task suggesting to the researchers that a pattern of consuming junk food, not just the occasional binge, was responsible for the effects that were seen. Of note, by the end of the six-month study period, the rats on the junk food diet grew large numbers of tumors throughout their bodies. The lean rats had fewer, smaller, and more localized tumors.
Lead researcher, Aaron Blaisdell, stated, “The idea commonly portrayed in the media that people become fat because they are lazy is wrong. Our data suggest that diet-induced obesity is a cause, rather than an effect of laziness. Either the highly processed diet causes fatigue or the diet causes obesity, which causes fatigue.”
Modern lifestyles are too often characterized by poor quality diets filled with highly processed foods, coupled with sedentary lifestyles. This is a toxic combination and radical departure from the lifestyles (for example during Paleolithic times) practiced by our not-so-distant ancestors; a lifestyle our bodies simply have not had enough time, evolutionally speaking, to adapt to. Our Paleolithic bodies in a modern silicon world leads to a host of chronic conditions known, collectively, as Diseases of Civilization (DOC’s) – heart disease, cancer, obesity, diabetes, chronic fatigue, fibromyalgia, arthritis, depression, multiple sclerosis and more.
Cleaning up one’s diet can go a long way toward helping you avoid or at least delay the onset of these DOC’s. One of the healthiest diets is a Mediterranean style diet. Read our earlier blog post - Mediterranean Diet Magic - for more information.
Blaisdell, A.P., Lau, Y.L.M., Telminova, E., et al. Food quality and motivation: a refined low-fat diet induces obesity and impairs performance on a progressive ratio schedule of instrumental lever pressing in rats. Physiology & Behavior, 2014; 128: 220.