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health and human development

Gene Identified for Obesity, Physical Activity, Sex Behaviors in Mice

A team led by University of Massachusetts Amherst researcher Deborah J. Good has identified a gene that appears to play a role in obesity, physical activity, and sex behaviors in mice. Good works with so-called “knock-out” mice, which have a specific gene deleted. Scientists then monitor the animals for changes in their physiology and behavior, in an effort to determine the gene’s role. Her findings are detailed in the current issue of the journal Physiology and Behavior. The project is funded with a four-year, $1 million grant from the National Institute of Diabetes and Digestive and Kidney Diseases, and a two-year, $70,000 grant from the National Institute of Child Health and Human Development, both of the National Institutes of Health.

Portion size matters: Given too much, we eat it

Almost nobody can stop eating at just one normal serving if there’s extra food on their plate, Penn State researchers have shown, and this tendency coupled with the spread of megaportions may be contributing to the American obesity epidemic. In the first systematic, controlled study of the response to portion size in adults, the researchers found that the bigger the portion, the more the participants ate. On average, they ate 30 percent more from a five-cup portion of macaroni and cheese than from one half its size ? without reporting feeling any fuller after eating. Dr. Barbara Rolls, who holds the Guthrie Chair of Nutrition in Penn State’s College of Health and Human Development, led the study. She says, “Men and women, normal-weight and overweight individuals, restrained and unrestrained eaters, all responded to larger portion size by eating more.”

Hormone breast cancer risk normalizes after stopping pills

Researchers confirmed that a daily, combined dose of estrogen and progestin increases breast cancer risk in post menopausal women, but added that this risk begins to return to normal about six months after women stop taking the hormones. “It is reassuring that breast cancer risk begins to return to normal six months after women stop combined dose estrogen-progestin therapy,” said Duane Alexander, M.D., Director of the NICHD. “Women, in consultation with their physicians, need to make the most informed decision possible. The study authors have provided them with one more piece of important information.”

Calorie listings don’t encourage overeating, study says

You really don't want to knowLabeling foods “low-fat” is suspected of encouraging consumers to overeat. If that box of Ho-Ho’s claims to be low-fat, heck, why not down the full dozen? But a study from Penn State says the same is not true of the listing of caloric content. “Some studies have shown that people take larger portions of foods labeled ‘low fat’ ? using the label as a license to eat more. This study shows that energy density labels are unlikely to undermine the benefits of offering foods with fewer calories per ounce.”