"The difficulty lies, not in the new ideas, but in escaping the old ones, which ramify, for those brought up as most of us have been, into every corner of our minds."
-John Maynard Keynes
High Protein Diet:
The Way To Go, Bro'.
Numerous studies have shown that high-protein diets increase satiety and thus facilitate fat loss. Furthermore, epidemiologic studies show a significant relationship between increased protein intake and lower risk of hypertension (high blood pressure) and coronary heart disease. Also, purported adverse effects of high-protein diets are false or at least greatly exaggerated.
A recent four-month study by Dr. Layman and co-workers examined the interaction of two diets (high-protein/moderate-carb versus low-protein/high-carb) with exercise on body composition and blood lipids in women during weight loss. Diets were equal in total energy and fats, but differed in protein content; 1.6 grams per kilogram of bodyweight per day in a high-protein group and 0.8 grams per kilogram in a high-carb group.
Not surprisingly, subjects in the high-protein and high-protein plus exercise groups lost more weight and fat and lost less lean mass than the high-carb and high-carb plus exercise groups. As expected, exercise promoted fat loss and preserved lean mass, so the combined effects of diet and exercise were additive for improving body composition.
The authors concluded,
"This study adds to the increasing body of evidence supporting protein-sparing (i.e., anti-catabolic) effects derived from maintaining higher protein intakes during energy restriction."
There's also evidence that higher protein intake improves weight management. For example, Dr. Lejeune and colleagues investigated whether the addition of protein to the diet might limit weight regain after a weight loss of five to 10 percent. One hundred and thirteen overweight subjects followed a very-low-energy diet for four weeks, after which there was a six-month period of weight management.
During weight management, subjects were randomized into either a protein group (30 grams of protein per day in addition to their own usual diet) or a control group. The protein group showed a lower weight regain and a decreased waist circumference. Interestingly enough, the results also indicated that weight regain in the protein group consisted of only fat-free mass, whereas the control group gained fat mass as well.
Low Fat Diet:
Decreases Testosterone Levels.
Testosterone separates the men from the boys. It promotes protein synthesis and growth of those tissues with androgen receptors. Testosterone effects can be classified as virilizing and anabolic, although the distinction is somewhat artificial.
Anabolic effects include growth of muscle mass and strength as well as increased bone density. Virilizing effects include maturation of the sex organs, a deepening of the voice, growth of the torso hair and so on.
Low-Fat Diet Study:
Thirty-nine healthy men were studied while they were consuming a high-fat/low-fiber diet and after an eight-week modulation switched to an isocaloric low-fat/high-fiber diet. After diet modulation, blood testosterone concentration fell, accompanied by small decreases in free (biologically active) testosterone.
The narrow-minded authors suggested that the low-fat diet modulates androgen levels and metabolism providing an unfavorable environment for the growth and development of prostate cancer .
While this hypothesis makes sense, they ignored the fact that low testosterone levels also have adverse effects such as decreased sex drive, poor erections, lowered sperm count, reduced muscle mass and so on. So, what's the bottom line? The low-fat diet may be good for your prostate, but it's not good for your dick and muscles!
Superior To Conventional Low-Fat Diet.
The glycemic index is a ranking of carbs according to the extent to which they raise blood sugar levels after eating. Foods with a high-glycemic index are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels.
Glycemic load builds on the glycemic index to provide a measure of total glycemic response to a meal.
Glycemic load = glycemic index [percent] x grams of carbs per serving.
In a recent study by Dr. LaHaye and co-workers at the Queen's University in Canada, 120 subjects who were advised to follow a low-glycemic load diet were evaluated and compared with 1,434 patients who were advised to follow the principles of "Canada's Food Guide to Healthy Eating."
As expected, the investigators found that the low-glycemic diet was superior to the "healthy eating" diet:
Subjects on the low-glycemic diet lost more weight at six months: 2.8 kilograms (2.2 pounds=1 kilogram) lost versus 0.2 kilograms gain.
The low-glycemic diet group had a greater reduction in abdominal lard: 2.9 centimeters versus 0.4 centimeters.
Subjects on the low-glycemic diet had a greater improvement in good cholesterol (HDL) high-density lipoprotein cholesterol, triglycerides and blood sugar control.
After one year of follow-up, the low-glycemic load subjects had maintained or even augmented the initial results.
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More recently, Dr. Stevenson and colleagues examined the effects of the glycemic index of post-exercise carbohydrate intake on endurance capacity the following day. On day one, subjects ran for 90 minutes at 70 percent VO2max. Thereafter, they were supplied with either a high-glycemic or low-glycemic diet, which provided eight grams of carbs per kilogram of body mass.
On day two, subjects ran to exhaustion at 70 percent VO2max. Interestingly enough, time to exhaustion during the second run was longer in the low-glycemic groups than in the high-glycemic group. The investigators suggested that the increased endurance capacity was largely a consequence of the increased fat burning following the low-glycemic recovery diet.
In sum, it's now clear that the conventional high-carb/low-fat diet is far from the ideal diet. Although Dietary Guidelines for Americans 2005 gives greater emphasis on increased consumption of whole grains rather than refined grains, this is unlikely to improve daylong glycemic control, because many so-called whole-grain products produce as much postprandial glycemia as do their white flour counterparts.
Bodybuilding.com gives the following sensible recommendations to decrease glycemic load:
- Use breakfast cereals based on oats, barley and bran.
- Reduce the amount of potatoes you eat.
- Enjoy all types of fruit and vegetables (except potatoes).
- Eat plenty of salad vegetables with vinaigrette dressing.
- Layman DK et al. Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr, 2005;135:1903-1910.
- Lejeune MP et al. Additional protein intake limits weight regain after weight loss in humans. Br J Nutr, 2005;93:281-289.
- Wang C et al. Low-fat high-fiber diet decreased serum and urine androgens in men. J Clin Endocrinol Metab, 2005;90:3550-3559.
- LaHaye SA et al. Comparison between a low-glycemic load diet and a Canada Food Guide diet in cardiac rehabilitation patients in Ontario. Can J Cardiol, 2005;21:489-94.
- Stevenson E et al. Improved recovery from prolonged exercise following the consumption of low-glycemic index carbohydrate meals. Int J Sports Nutr Exerc Metab, 2005;15, August.
- Brand-Miller J. Optimizing the cardiovascular outcomes of weight loss. Am J Clin Nutr, 2005;81:949-950.
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