The myth: Successful weight loss is simply a matter of willpower.
The reality: Like hair color, you inherit your metabolism, and metabolic characteristics vary greatly among individuals. Some of the best demonstrations that genes control metabolism involve research on identical twins. When many sets of twins were given the same reduced-calorie diet, all of them lost weight. However the amount of weight loss (and fat loss) varied widely across the whole group. And guess what? The individuals within each pair of identical twins lost very similar amounts of weight. That means that people with the same genes respond to energy restriction in the same way, but people with a different genetic makeup (in this case the different pairs of twins) have a wide range of responses, some losing easily and others very slowly1. The same similarity of response within each pair of twins and wide variation across the sets of twins occurred when they were put on an exercise program that burned 1,000 calories a day2. So don’t be frustrated if someone else is losing weight faster than you. If, despite doing everything right, you’re experiencing snaillike progress, you can blame some of it on your great-grandparents!
1. C. Bouchard, A. Tremblay, J. P. Despres, A. Nadeau, P. J. Lupien, G. Theriault, et al., “The Response to Long-Term Overfeeding in Identical Twins,” The New England Journal of Medicine 322 (1990), 1477–1482.
2. C. Bouchard, A. Tremblay, J. P. Despres, G. Theriault, A. Nadeau, P. J. Lupien, et al., “The Response to Exercise with Constant Energy Intake in Identical Twins,” Obesity Research 2 (1994), 400–410.