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

"Individual genetic differences in the numerous hormones and peptides made by the gut, brain, and fat cells (that regulate appetite, hunger, and satiety) may play a big role in predisposition to obesity and difficulty losing weight,” says Catenacci.

Researchers are only beginning to understand what might be at play here, and how it affects what and how much a person eats.

4. You don't like to exercise (it could be in your genes).

According to Daniel Pomp, PhD, from the University of North Carolina at Chapel Hill, animal research suggests that 25%-50% of an individual's propensity for voluntary exercise is under genetic control.

Pomp studies mice that genetically prefer to exercise because they were bred for high levels of wheel running. Expect more research in the next few years on "exercise genes" and how they might also be at play in humans.

5. Your mother ate a high-fat diet while pregnant.

There is some preliminary research in primates that suggests eating a healthy, moderate-fat diet is important for the future weight and health status of the developing fetus, regardless of whether the pregnant mother was obese or lean.

6. What you ate as a toddler could be affecting how easily you gain weight as an adult.

Research from Raylene Reimer, PhD, RD, a researcher from the University of Calgary, has indicated that the food we eat affects how active certain genes are in our body. "In particular, we believe that our diet has a direct influence on the genes that control how our bodies store and use nutrients," explains Reimer.

In Reimer's research with rats, a group that ate a high-protein diet when young packed on much more weight and body fat as adults compared to another group of rats raised on a high-fiber diet.

More research needs to be done to understand the mechanisms at work here, but this research suggests how complex weight gain really is.

Can't Lose Weight? Focus on Health

If several of these reasons apply to you, don't get discouraged. You can't change your genes, but you can change how you interact with your environment. The positive way to proceed is to eat and exercise for the health of it. Eating mostly healthy foods, avoiding overeating, and exercising regularly is important for your overall health.

And don't beat yourself up if you can't fit into that pair of skinny jeans. The truth is that people naturally come in all sorts of shapes and sizes, says Joanne Ikeda, MA, RD, nutritionist emeritus of the University of California Berkeley nutrition science department, who has spent her career researching weight and health.

"It's so sad that we are convinced that the normal range of human body sizes and shapes should fit into a narrow spectrum when size diversity is, in fact, what naturally occurs in the human population," Ikeda says.

SOURCES:

Victoria Catenacci, MD, researcher and practicing clinician, University of Colorado, Denver.

June Stevens, MS, PhD, chair, department of nutrition; American Institute for Cancer Research/World Cancer Research Fund distinguished professor, University of North Carolina- Chapel Hill.

Daniel Pomp, PhD, researcher, department of nutrition and department of cell and molecular physiology, University of North Carolina, Chapel Hill.

Robin Duncan PhD, postdoctoral fellow, department of nutrition science and toxicology, University of California, Berkeley.

Joanne Ikeda, MA, RD, nutritionist emeritus, nutrition science department, University of California, Berkeley.

Raylene Reimer, PhD, RD, associate professor, faculty of kinesiology, University of Calgary. Wang, G-J Proceedings of the National Academy of Sciences of the United States of America, online edition, Jan. 20, 2009.

News release, Journal of Clinical Investigation, Jan. 19, 2009.

News release, University of Calgary Press for the Journal of Physiology (London), Jan. 14, 2009.

Reviewed on March 24, 2009

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Last Editorial Review: 3/24/2009 6:46:26 PM