Why Can't I Lose Weight? (cont.)

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.

Further, because men tend to be larger than women, they tend to burn more calories doing the same exercise as women.

"If they both run at the same pace for one hour, the woman will burn 500 calories, for example, while the man will burn closer to 700 calories," says Catenacci.

As if this weren't unfair enough, men also seem to be better at suppressing hunger when presented with food, according to findings of a recent study.

After 23 healthy, non-obese people fasted for 17 hours, researchers used cognitive inhibition techniques to try to suppress thoughts of hunger. They found that the technique significantly lowered the desire for food only in men. Subsequent brain scans of the men showed a decrease in activation in brain regions that are known to play a role in processing our awareness of the drive to eat.

3. You experience hunger, satisfaction, and stress differently than others.

Stevens believes that differences in how people experience hunger and cope with stress are important in determining who becomes overweight and who doesn't.