Why do some people gain weight more easily than others?

Dr. Michael Roizen, MD
Internal Medicine
Some people are more prone to being overweight than others. Two factors are genetics and behaviors. Certainly, one key factor is heredity. Some of us are born thin, and some of us aren't. Our genes determine all kinds of influences on height, weight, and metabolic rate, and these vary incredibly from person to person. Also, some of us are born with an emotional make-up, and acquire emotional predispositions, that make it harder or easier to lose weight. The study of genetic factors affecting weight gain is a burgeoning field, and scientists have discovered some genes and gene products that are tied to weight gain. One of the first hormones tied to fat regulation-leptin-was characterized in the now-famous studies of "fat mice": Mice with genetically-created obesity were given injections of leptin and lost weight. Despite the initial belief that a magical new weight-loss drug had been found, the discovery of leptin proved how complicated the genetics of food metabolism and weight gain are. Subsequent investigation showed that leptin is just one hormone out of many involved in a complicated metabolic pathway. Some people with genetically-caused weight problems have leptin-related disorders, but others don't. Some people clearly have gherlin-related disorders. There are probably going to be other hormones discovered as well. We hope that magic pills will be invented that allow us to combat the effect of each and every one of these potential hormones. However, no one knows what the future holds in this regard. Weight regulation is a complex genetic trait: Many different genes and proteins interact to determine body size. We are still years from understanding the interactions. Fortunately, heredity isn't everything.
The RealAge Makeover: Take Years off Your Looks and Add Them to Your Life

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The RealAge Makeover: Take Years off Your Looks and Add Them to Your Life

Why not live at 60 feeling like you did at 35?Thousands of Americans are younger today than they were five years ago. How is that possible? By following the specific recommendations that reverse...

Continue Learning about Obesity



If you have too much body fat, you are obese, just like over 70 million other Americans. It happens because you eat more calories than you use, and your body converts the excess to fat. There are lots of reasons that this can happ...

en. Our lifestyle may lack exercise, we are given portions that are too big and too caloric when we eat, and some of us are just more efficient genetically at converting food into fat.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.