Why Can't I Lose Weight?

Have you ever felt like trying to lose extra pounds or keep them off is just more difficult for you than for other people? Recent research suggests you might not be imagining this. For some people, thanks to a combination of genetics and physiological differences, it really is easier to put on weight and harder to take it off.

Most of these people are women, who have a different genetic blueprint than men. Up until maybe 100 years ago, it was favorable for women to have extra fat stores and efficient metabolisms. This helped to ensure women's survival during times of famine and illness, and women's ability to nourish babies while pregnant and breastfeeding.

"We know for sure it's both genetic and environmental why some people are overweight and obese," says June Stevens, a distinguished professor at the University of North Carolina at Chapel Hill.

The genetic differences that determine a person's tendency to gain weight are less noticeable in environments where exercise is a part of everyday life and where there is NOT an abundance of great-tasting, affordable food. Most Americans, of course, live in the opposite situation. Stevens describes it as an "obesogenic" environment: a set of circumstances that encourages people to eat and drink more calories than they expend, and thus become obese.

Here are some of the possible reasons why the weight loss odds could be stacked against you, making it feel like you just can't lose weight:

1. You have a low resting metabolic rate, and high metabolic efficiency.

If you have a lower resting metabolic rate, your body spends fewer calories maintaining your body at rest than someone your size with a higher rate. And, if your body is metabolically efficient, it burns fewer calories while in motion.

Differences in resting metabolic rates and metabolic efficiency may explain up to about 22 pounds of weight gain, says Victoria Catenacci, MD, a researcher with the University of Colorado at Denver. This could help explain differences in normal weight vs. overweight, but many researchers believe that higher levels of excess weight (clinical obesity) are probably a result of excessive food intake and/or low physical activity.

2. You are female.

There are a number of reasons why men have the weight loss edge over women.

First of all, men have more muscle mass, compared to women, and women have a higher percentage of body fat than men. Muscle tissue burns more calories at rest than fat tissue. So it's no surprise that men's resting metabolic rate tends to be significantly higher than women's.

Also, women often deposit extra body weight in the hips, legs, and buttocks, while men tend to store extra weight in the midsection, says Robin Duncan, PhD, a postdoctoral fellow at University of California Berkeley's Department of Nutrition Science and Toxicology. Extra fat around the gut is more actively recruited during times of energy need and thus may be easier to lose than fat on the legs and hips, explains Duncan.