Exercise more, eat less? There’s a lot more to it, says scholar

Bouchard, director of the Human Genomics Lab at Pennington Biomedical Research Center in Baton Rouge, La., studies the genetics of obesity and says there are dozens of factors involved in determining whether or not a person becomes overweight or obese.

"It's a complex problem because there are so many drivers," says Bouchard, author or coauthor of several books and more than 1,000 scientific papers, and a former president of the International Association for the Study of Obesity. "Approaches focus on only a few and forget that while we control them there is compensation taking place elsewhere; there are other drivers that come into play."

He divides those drivers into four categories: social, environmental, behavioral and biological.

Social factors include less access to nutritious foods, more recreational eating, powerful and constant advertising, large food portions, poor school meals, eating on the run, food pricing and fewer meals cooked at home.

Our physical environment affects eating habits as well, says Bouchard, such as the absence of sidewalks, reliance on automobiles, building design and environmental pollutants.

Behavioral factors such as spending less time in strenuous activity, taking medications known to increase body weight, the absence of breast-feeding, eating corn fructose syrup, an increase in sedentary jobs and high-fat diets.

And biological factors such as genetics, viruses, gut microbiota (microorganisms living in the intestine), adipose tissue (body fat) biology, and metabolic rates can all affect weight and many are not within a person's control.

"The biology is very complex," Bouchard notes. "The response to environmental, social and behavioral factors is conditional on the genotype of an individual. Your adaptation to a diet or a given amount of exercise is determined by your genes."

More research is needed, he says, but there is a strong probability that diet and exercise programs for weight control or disease prevention will one day be tailored to an individual's genetic makeup. He asks, "Can we meet the challenge of identifying genomic predictors of the ability of a given person to respond favorably to a specific combination of food and exercise? I believe that we can."

Bouchard and his colleague, Dr. George Bray, have edited the latest version of the "Handbook of Obesity," the definitive guide on the subject, which thoroughly discusses the many contributing factors, treatment and prevention of this chronic disease.