Weight loss in older women may be reflective of more than just fat loss. It may be indicating a loss of muscle tissue as well. And that's not a good thing.

Researchers at the University of Illinois recently released a study in which they found that the consumption of extra protein in postmenopausal women who were dieting seemed to help preserve muscle health without sabotaging weight loss efforts. A high-protein weight- loss diet may provide satiety as well, especially if the protein is consumed at intervals throughout the day.

Thirty-one postmenopausal obese women were enlisted and split into two groups. Each group consumed a 1,400 calorie diet based on the USDA's MyPyramid. One group was given a protein supplement of powdered whey in the morning and again later in the day. The other group was given a placebo that contained carbohydrate.

The women in the study were encouraged to participate in some form of light exercise such as stretching or walking, given diet instructions and examples of healthy menus, and provided with a scale to measure portion sizes. Participants were assessed for strength, balance, and the ability to perform certain physical tasks before and after the six-month study. In addition, the muscle volume of each woman's right thigh, the amount of fat on the thigh, and the amount of fat within the thigh muscle were measured using magnetic resonance imaging (MRI).

Weight loss was greater in the women consuming the protein supplement by 3.9 percent. This group of women also gained about 5.8 percent more thigh muscle volume than those who consumed the placebo.

In both groups of women their strength decreased as they lost weight. However, the women who consumed more protein showed an increase in the amount of muscle relative to fat and that was beneficial in terms of balance and performance. The researchers concluded that even though the women lost strength, their lower weight helped with other aspects of physical function, and hypothesized that more vigorous exercise while dieting could preserve more muscle.

The loss of muscle in older women who lose weight can affect their strength, their balance, and how well they can physically function doing things like getting out of a chair or climbing stairs, according to Mina Mojtahedi, one of the researchers. Women with less weight to carry are more likely to maintain their mobility and independence as they grow older.