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The
Health Zone Newsletter In
this issue: Protein
+ Exercise May Promote Weight Loss
New research shows o bese women who exercised regularly and ate a reduced-calorie diet high in protein lost more fat and less muscle than those who ate a similar diet high in carbohydrates. Both diets contained the same number of total calories and percentage of calories from fat. "Both diets work because, when you restrict calories, you lose weight. But the people on the higher-protein diet lost more weight," says researcher Donald Layman, PhD, professor of food science and human nutrition at the University of Illinois, in a news release. Researchers say women on the high-protein diet also lost more weight around the abdominal area. "There's an additive, interactive effect when a protein-rich diet is combined with exercise. The two work together to correct body composition; dieters lose more weight, and they lose fat, not muscle," says Layman. Protein May Keep Muscle, Burn Fat In the study, researchers compared the effects of a high-protein, low-carbohydrate diet against a high-carbohydrate, low-protein diet combined with exercise in 48 obese women. Both diets contained 1,700 calories, 30% of calories from fat, and about 17 grams of fiber. But women on the high-protein diet substituted high-protein foods, such as meats, dairy, eggs, and nuts, for foods high in carbohydrates, such as breads, rice, cereal, pasta, and potatoes, to get about 30% of their total calories from protein. Women on the high-carbohydrate diet, in comparison, ate about half that amount of protein and got about 60% of their daily calories from carbohydrates. Both diets fall within the acceptable nutrient levels prescribed by the Institute of Medicine, according to the researchers. Both groups participated in a high- or low-level exercise program. The high-exercise group consisted of five 30-minute walking sessions and two 30 minute weight lifting/stretching sessions per week. Exercise for the low-intensity group emphasized voluntary lifestyle recommendations of a minimum of 30 minutes of walking five days/week. After four months, the results showed that both groups of dieters lost weight, and those who exercised more lost less muscle tissue and more fat. High-protein dieters in the high-exercise group lost an average of 22 pounds and less than a pound of lean muscle. High-carbohydrate dieters in the high-exercise group lost an average of 15 pounds but lost more than 2 pounds of muscle. But the real key to losing weight while maintaining muscle appears to be exercise. The high-protein, low-exercise dieters lost an average of 19 pounds but lost over 4 pounds of muscle. The high-carbohydrate, low exercisers lost 17 pounds, but nearly 6 pounds of that came from muscle. Nearly 100% of the weight lost in the high-protein exercise group was fat, while 25%-30% of the weight lost in the high-carbohydrate exercise group was muscle, says Layman. Eating
Soy Foods May Reduce Bone Fracture Rate
Women who eat the most soy foods have the fewest bone fractures after menopause. That's the word from a study of 24,403 postmenopausal Chinese women. Within 10 years of menopause, the 20% who ate the most soy foods reported half as many fractures as the 20% who ate the least soy. Soy protected against fracture at every level of consumption over 5 grams a day. But those who ate more than 13 grams of soy a day - getting more than 60 milligrams of soy isoflavones a day - got the most benefit. Soy protected against bone loss but did not appear to strengthen weak bones, says researcher Xiao-Ou Shu, MD, PhD, MPH, professor of medicine at Nashville's Vanderbilt-Ingram Cancer Center. Shu and her colleagues report the findings in the Sept. 12 issue of Archives of Internal Medicine. "We saw the protective effect of soy was much better for women who just had menopause, within 10 years," Shu tells WebMD. "Afterward, soy is still protective, but it not as much as in the recently menopausal women." 2 Cups of Soy Milk - or Less The highest level of consumption among Chinese women was about 13 grams of soy protein a day. A cup of soy milk contains about 6.6 grams. A half piece of tofu contains about 8 grams. "That is definitely manageable," Shu says. "Please note that women in the middle consumption group also had a 30% risk reduction for bone fracture. The amount of soy food consumption in that group is about a half piece of tofu or a little more than 1 cup of soy milk per day." The Preventive Power of Soy Just about everyone knows that calcium is needed to build strong bones. But soy has a different bone-protecting effect, says soy isoflavone expert Kenneth D.R. Setchell, PhD, of Children's Hospital Medical Center in Cincinnati. Setchell's research team is in the middle of a long-term experiment. The researchers are giving postmenopausal women two glasses of soy milk every day. Half the women get soy milk with a major soy component - soy isoflavones - removed. "We found that women who consumed the soy isoflavones maintained stable bone mass," Setchell tells WebMD. "They had no bone loss in two years. And that has now been extended to four years." The women who did not get isoflavones in their soy had significant bone loss - about 4.5%. Bad as that sounds, Setchell says, it's not as much bone loss as most women would see at menopause if they were not taking some kind of bone-enhancing treatment. He thinks soy protein may also play a role in bone protection. But whatever it is about soy and bone, the key word is protection. Setchell and Shu both stress that soy is not a treatment for bone loss - its effect is to prevent bone loss. More Health Benefits of Soy Bone loss isn't the only reason to consume soy foods. "It is not just for bone fracture. It is a great health benefit," Shu says. "Most studies indicate that soy is pretty safe, and the evidence is quite strong that it protects against coronary heart disease. There are also some data indicating soy may reduce the risk of breast cancer. Taking all those things together, I recommend women eat soy as much as they can." But don't just add soy to your diet, warns Leslie Bonci, MPH, RD, director of sports nutrition at the University of Pittsburgh Medical Center. "This is not an additive. You still have to watch your calories," Bonci tells WebMD. "If you add it into your diet, think about what you are wiling to give up. Otherwise you are going to get too big for your bones." Bonci
also warns that soy supplements aren't a replacement for soy foods. If
you're going to go for soy health benefits, she says, do it with foods
- not pills. |
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