a1 Division of Kinesiology and Functional Foods, Laval University, Ste-Foy, Québec, Canada, G1K 7P4
a2 Institute of Nutraceuticals and Functional Foods, Laval University, Ste-Foy, Québec, Canada G1K 7P4
a3 Pennington Biomedical Research Center, Louisiana State University, Baton Rouge LA 70808, USA
Studies of monozygotic twins in the context of overfeeding and energy deficit experiments have shown that gene–environment interactions affect energy balance. From a clinical standpoint, this implies that some individuals are more susceptible to body-weight gain or loss than others because of genetic differences. This opens new perspectives in predictive medicine. In the future, health professionals should be able to count on early diagnosis of individuals at risk for developing long-term metabolic problems and obesity or for not responding adequately to clinical interventions. However, before predictive medicine is in a position to contribute significantly to prevention or treatment of patients, an enormous amount of work has to be done to identify all genetic and environmental factors of relevance, and their network of interactions.