| Protein + Exercise = healthful weight loss
From the "tell us something we didn't know" file: A recent study by the University of Illinois reports something many low carbers have noticed in their own "research": Exercise is much more effective when you consume lots of protein.
The study, published in the August 2005 Journal of Nutrition, included 48 adult women, some of whom ate a protein-rich diet of meats, dairy, eggs and nuts. The other group ate a diet based on the food guide pyramids - less protein and more carbs such as breads, rice, cereal, pasta and potatoes - effectively pitting what low-carbers think of as "the old way of eating" against a more carb-controlled approach.
Notably, the women consumed the same number of calories. "Both diets work beacuse, when you restrict calories, you lose weight. But the people on the higher protein diet lost more weight. Some people refer to this as the metaboli advantage of a protein-rich diet," says Donald Layman, a University of Illinois professor of food science and human nutrition. (If you've read any of Dr. Atkins' books, you'll recognize the term 'metabolic advantage.' He maintained that a diet rich in proteins and good fats controls appetite by keeping blood sugar levels stable).
Add exercise, however, and results are dramatic. The study included two levels of exercise. One group usually walked two to three times a week - for a total of less than 100 minutes. The other group did five 30-minute walking sessions and two 30 minute weightlifting sessions per week. Both programs helped spare lean muscle tissue and encouraged fat loss. But the high protein/high exercise group lost much more weight - and nearly 100 percent of it was fat, according to Layman. In the high carb/high exercise group, up to 25 to 30 percent of the weight lost was muscle. "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.
The documented benefits of carb control and exercise didn't end there. Those in the high protein group lowered their triglyceride levels significantly and reduced "trunk fat" - both of which, Layman says, are risk factors associated with heart disease. "Exercise helped dieters lose an even greater percentage of body fat from the abdominal area," he says.
The wonder ingredient in the protein rich diet? The amino acid leucine, which works with insulin to stimulate protein synthesis in muscle. "the diet works because the extra protein reduces muscle loss while the low-carb component gives you low insulin, allowing you to burn fat," he said. "We believe a diet based on the food guide pyramids actually does not provide enough leucine for adults to maintain healthy muscles. The average American diet contains 4 to 5g leucine, but to get the metabolic effects we're seeing, you need 9 or 10g," he noted. So how do you up your intake? He recommends adding high-quality proteins like dairy, meat and eggs to your diet.
Low fat/calorie vs. low-glycemic diets: Which is better for your heart?
More and more health and weight conscious consuemrs are adopting a low-glycemic load diet - and new research from the Children's Hospital in Boston indicates that they're making a good choice for cardiovascular health.
There, researchers compared the efficacy of a low-glycemic-load diet to that of a low-fat diet in lowering the risk of cardiovascular disease in obese young adults. Once again, the low-fat approach comes out on the short end.
Over the course of a year, 23 obese young adults ate either an "experimental" or a "conventional" diet. The experimental diet consisted of nearly unlimited low-GI foods, with 45-50 percent of energy derived from carbs and 30-35 percent from fat. The conventional diet group's energy intake created a 250 to 500 calorie/day deficit, with less than 30 percent coming from fat and 55 to 60 percent from carbs.
The results? Both gruops lost weight and kept it off. Likewise, measurements of cholesterol, blood pressure and insulin sensitivity didn't differ much between the two. The big news is in substances you might never have heard of: Plasma triacylglycerols, fatty acid molecules associated with ischemic heart disease. In the experimental diet group, levels decreased by 37.2 percent, comapred to 19.1 percent in the conventional group. Similarily, concentrations of plasminogen activator inhibitor 1, a substance that increases the risk of serious blood clots, decreased in the experimental diet group by 39 percent - but increased 33.1 percent in the conventional diet group!
A similar study out of Harvard University published in the Journal of the American Medical Association last November drew a similar conclusion: that a low-glycemic diet is better for reducing cardiovascular risk factors than the low-fat diet. Furthermore, the research suggests that low-glycemic diets don't slow the metabolism the way low-fat diets do, so low-glycemic dieters feel less tired, cold and hungry - and more apt to stick with such an eating regimen.
Source: Low Carb Energy Magazine. | |
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December 13th, 2005, 09:12 AM
Protein + Exercise = healthful weight loss 
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