First, let’s start with the definition of obesity. “Obesity occurs when, over time, the body takes in more calories than it burns,” according to The Endocrine Society. When a person’s Body Mass Index (BMI) is over 30, that person is considered obese.
Because obesity is related to the number of calories a person consumes, a GM crop would have to contain considerably more calories than non-GM varieties of that crop to be linked to obesity. But the fact is that GM crops are carefully reviewed to make sure they are substantially equivalent to non-GM crops in their composition and nutritional qualities. This includes levels of protein, carbohydrate, fat, vitamin, mineral, fiber, moisture, among others. The caloric value of food from a GM plant will be in the same range as the comparable non-GM plant.
Whatever is causing obesity today, it isn’t the calories from GM plants.
Some people have claimed that GM crops cause obesity in ways unrelated to the caloric content of the food. However, more than 150 studies have been conducted and the results of these studies do not provide any cause for concern about weight gain or other negative impacts from GMOs.
Some have raised concern that High Fructose Corn Syrup which is processed primarily from GM corn may be especially responsible for the obesity rise. However, research has shown the HFCS provides the same calories and is used by the body in the same way as table sugar. Excessive calorie intake, regardless of the source, with inadequate physical activity is the primary cause of obesity in most people.
Some companies are using genetic modification to improve the nutritional value of crops, such as soybeans. These nutritionally-improved GM soybeans contain more oleic acid—an unsaturated fatty acid found in olive oil—and significantly less saturated fatty acids than traditional soybeans.
“Feed from Transgenic Plants in Animal Nutrition,” Gerhard Flachowsky, Institute of Animal Nutrition, German Federal Research Institute for Animal Health, Braunschweig, Germany, GMSAFOOD Conference, Vienna, March 2012 http://www.gmsafoodproject.eu/UserFiles/file/keynotes%20presentation/FLACHOWSKY.pdf
For information about obesity and its causes: