Nutrition for slimming diet
Anti-fat impacts of different sources of protein powder
Food choices will greatly influence our ability to gain or lose fat. It has long been said that a calorie is a calorie and that with equal caloric intake, all diets provide comparable fat loss. A new study shows that nothing is more false than this old belief.
Men and women received either a high protein meal (50% of calorie intake) or a high carbohydrate meal (95% of calorie intake) (1).
The thermogenic effect (wasted calories in the form of heat) of protein was 14% compared to 6% with carbohydrates, which is half as much. The oxidation (burning) of fats reaches 16% with proteins against 11% with carbohydrates.
Bottom Line: By eating protein, we waste more calories and burn more fat than by eating carbohydrates. So, for an equal calorie intake, we will lose weight faster thanks to protein.
But the study does not stop there. It also shows that some proteins are more effective than others. Thus, the subjects received either whey, or casein or soy protein.
Whey has the strongest thermogenic effect of all proteins; it is 20% higher than casein. The latter is much more effective than soy, which turns out to be the poorest protein.
For anti-fat action, whey, with a potency 8% greater than that of casein, is again the best. Casein is however 10% more effective than soy, which still ranks last among proteins.
Regarding the elevation of the level of blood amino acids, this study confirms the speed of whey, the slowness of casein and the mediocrity of soybeans.
Thus, one hour after taking whey, the level of essential amino acids in the blood is 13% higher than with casein. Two hours after intake, the amino acid level is 17% higher with whey than with soy. The amino acid level drops back to normal 5 hours and a half after taking it with whey as well as soy.
One would have expected that with a smaller increase induced by soybean, the latter would produce a prolonged effect. But, despite a reduced ability to quickly raise the level of amino acids in the blood, the effect of soy remains short-lived. On the other hand, with casein, the level of amino acids remains high, even after 5:30, which testifies to the long-lasting impact of this protein.
A second study looked at the long-term effect of whey on fat loss. Adults, men and women, received a classic diet, called "balanced" or a diet enriched with whey isolate for 8 weeks (2).
In both cases, the calorie intake was the same.
Thanks to whey, subjects lost 9.7kg against 6.1kg with the "balanced" diet. The fat loss amounts to 8.77kg with whey compared to 5.45kg with the classic diet, i.e. a difference in efficiency of 61% between the two diets.
But most strikingly, it is the targetable areas of fat loss thanks to whey. The latter concentrates the loss of centimeters on the stomach with an efficiency 57% higher and on the thighs with an efficiency twice as high as the conventional diet.
(1) Acheson KJ. Protein choices targeting thermogenesis and metabolism. Am J Clin Nutr 2011;93 525-534
(2) Aldrich ND. Varying protein source and quantity do not significantly improve weight loss, fat loss, or satiety in reduced energy diets among midlife adults. Nutr Res. 2011 Feb;31(2):104-12.