* In one of the first studies on the effects of weight loss on sexual quality of life, Martin Binks, director of behavioral health at the Duke Diet and Fitness Center in Durham, N.C., found that a weight loss of 10% of total body weight can significantly improve problems related to sexuality. These included feeling undesirable, not wanting to be seen undressed and not enjoying sex. The rate of women who said they felt sexually unattractive fell from 67.7% to 26.4% one year after they started a weight loss program.
* A big part of weight loss is controlling portion size -- but that is easier said than done, according to two new studies.
In one of them, scientists from Penn State University found that people eat more food when served larger portions over time, instead of naturally cutting back to compensate. When presented with larger-than-normal portions over an 11-day period, people consumed an average of 16% more calories per day during the period. The only food group that the study participants did not eat more of was fruits and vegetables.
In another study, Brown Medical School scientists found that snacking on foods packaged as individual servings doesn't lead people to eat less than they would if eating the same food out of a large bag or box. The total amount of food available, not the package or portion size, provides the main cue for how much to eat.
* Americans are losing interest in low-carb products but are more aware of the need to avoid trans fatty acids in their foods, according to a new survey from Aramark, the food-service giant headquartered in Philadelphia.
An online survey of more than 5,000 U.S. adults taken in January showed that more people are concerned about their intake of trans fatty acids, which can increase cholesterol levels and are linked to heart disease, compared with a 2003 survey.
A federal law will take effect in 2006 requiring food manufacturers to list trans fatty acids on labels, but consumers still struggle with how to avoid them in meals prepared outside of the home, says Christopher Malone, senior vice president of marketing at Aramark. (Americans now consume an average of 5.6 meals a week away from home.) Survey participants also said they wish they had more options for ordering half-portions and low-fat foods when dining out.
* If you're trying to lose weight, plan on lots of exercise, say the authors of a new study. In the longest study to date examining duration of exercise on weight loss, researchers from the University of Pittsburgh found that getting about five hours per week of exercise leads to the greatest weight loss among obese adults. That is twice the amount recommended to the general public to achieve good health.
The study followed 191 adult women who were assigned to one of four exercise regimens along with a low-calorie, low-fat diet. At the end of two years, the women in the highest-duration exercise group lost the most -- about 7.2% of their initial body weight. Dieters need to sustain about 270 to 300 minutes of exercise a week to achieve and maintain weight loss, said John Jakicic, lead author of the study.