High Protein Or High Carb Diet?
The experts continue to try to determine the ideal combination of calories that should come from protein, carbohydrates, and fats for Americans hungry to lose weight. The National Academies' general guidelines announced recently, suggest most Americans get between 10%-35% of calories from protein, 45%-65% from carbohydrates, and 20%-35% from fat.
Since high-protein foods, such as meats, are often loaded with harmful saturated fats, some experts suggest avoiding them in order to reduce both the waist-line and heart disease risk. But in practice, eating patterns often result in excess intake of the simple carbohydrates that boost risk of obesity and Type 2 diabetes.
Research suggests the key to losing fat while maintaining muscle can be found in one ingredient in protein-rich animal foods. Nutritionist Donald Layman, PhD, says protein-rich foods high in the amino acid leucine help maintain muscle mass while reducing body fat.
In a study of exercise and how muscle develops, he found that to lose weight leucine has a particularly unique effect in that it is light on muscle proteins, so you only lose the fat and not the muscle. " While most dietary plans talk about protein as percent of total calories, we look at protein needs based on a person's individual body weight and projected leucine intake to lose weight without losing lean muscle."
Leucine, which isn't produced by the human body, is found in protein-rich animal foods such as beef, chicken, fish, dairy, and eggs.
Two studies, funded by beef producers, Kraft Foods, the USDA and Illinois Council on Food and Agricultural Research, were recently reported. In the February issue of the Journal of Nutrition, a higher-protein, leucine-rich regimen was compared with the typical high-carbohydrate American diet on 24 middle-aged women who averaged about 182 pounds. Both eating plans fell within the recommended intake ranges for protein, carbohydrates, and fat under guidelines issued by the National Academies' Institute of Medicine.
All the women consumed about 1,700 calories a day and the diet compositions were as follows:-
| DIETS |
| Components |
Protein-Rich Diet |
Carbohydrate-Rich Diet |
| Protein |
30% |
16% |
| Carbohydrates |
41% |
58% |
| Fat |
29% |
26% |
| Grams of Protein/Body-weight |
0.73 |
0.36 |
Contrasting Fortunes
Though all the women lost about 16 pounds each, those in the higher-protein group lost more body fat and retained more lean muscle than those in the high-carb group.
Four months later the higher-protein group had continued to lose weight while the high-carb group had plateaued and lost no additional weight. The higher-protein group had lower blood sugar levels, making them less prone to Type 2 diabetes.
However, those eating the more typical high-carb diet had:
- lower cholesterol levels.
- Their "bad" LDL cholesterol levels dropped 16%
- Their total cholesterol was down 12% - that's nearly twice as much as those getting more protein.
There was no change in triglyceride levels in the high-carb group, but the higher-protein group averaged a 22% decrease.
These contrasting results left one noted nutritionist with mixed feelings. " This is certainly interesting and stresses the need for us to reassess where our focus should be in determining exactly how much we should be consuming of protein, carbohydrates, and fat", says Alice H. Lichtenstein, DSc, professor of nutrition at Tufts University and vice chairwoman of the nutrition committee of the American Heart Association.
Special Note
In this study all the foods were provided free and the participants getting more protein got very lean meats which might not be representative of everyday experience. In practice, the LDL cholesterol position could be much worse for high protein consumers because of the probable consumption of less lean beef.
Conclusions
High-protein Diet
- Lose weight more rapidly over an extended period of time.
- Less prone to Type 2 diabetes
- Risk raising your LDL (bad) cholesterol level.
- Instead of meat, an alternative source of protein could be broiled fish, non-fat dairy products, and legumes.
High-Carb Diet
- Lose weight more slowly over a shorter period of time.
- Lower LDL (bad) cholesterol
- Risk raising tendency to Type 2 diabetes.
07/25/03
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