Nutrition Performance - Macronutrient Update “A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.”—Maxwell Planck The Australian government’s Better Health Channel recently told us, “Some weight-trainers and bodybuilders believe that high-protein diets lead to increased muscle mass. This isn't true. It is stimulation of muscle tissue through exercise, not extra dietary protein, that leads to muscle growth.” MD readers know that this statement was nothing but a bunch of BS. A high-protein diet supports lean body mass gain in conjunction with a resistance training program. So, when it comes to bodybuilding nutrition, you cannot trust the government or health organizations. Simply stated, they don’t have a clue what the heck they’re talking about. With that said, this article examines the latest findings on macronutrient intake. High Protein/Low Fat vs. Standard Protein/High Fat When energy intake is matched and fat intake is reduced to about 30 percent of energy, the replacement of a moderate percentage of energy from carbohydrate with protein has been shown to enhance fat loss and to spare muscle mass. Furthermore, there are numerous studies reporting greater improvements in blood sugar control, insulin sensitivity and the blood lipid profile after weight loss with high-protein diets than after a standard-protein diet. However, a pertinent question is whether, in the context of low-carb diets, the high-protein or the high-fat diet is better at improving fat loss and health in general. So, Dr. Natalie Luscombe-Marsh and colleagues at the University of Adelaide in Australia compared the effects of two isocaloric diets (that differed in protein and fat content) on weight loss/fat loss, blood lipids, appetite regulation and energy expenditure after test meals.1 This was a parallel, randomized study in which subjects received either a low-fat, high-protein diet or a high-fat, standard-protein diet during 12 weeks of energy restriction and four weeks of energy balance. Fifty-seven overweight and obese volunteers completed the study. The main finding of this study was that the low-fat/high-protein diet and the high-fat/standard-protein diet (high in monosaturated fat) were equally effective at reducing bodyweight, improving insulin sensitivity and improving heart disease risk factors. So, it’s becoming increasingly clear that restriction of carbs in a low-fat/ moderate-carb diet or high-protein diet may be beneficial in improving body composition compared to a low-fat/high-carb diet (i.e., the American Heart Association diet), possibly by reducing insulin levels and thus, enhancing breakdown of stored fat. Not surprisingly, the experimental diets had no adverse effects on kidney function, blood pressure or markers of bone turnover. In summary, if you want to gain body fat and lose muscle mass, then the AHA diet is clearly the best choice. Protein Supplementation: Milk vs. Soy Dr. Stuart Phillips and co-workers at McMaster University in Canada examined how a protein source (milk vs. soy) affects the processes of muscle protein synthesis (i.e., anabolism) and muscle protein breakdown (i.e., catabolism) after resistance exercise.2 Their first study was an acute examination of how milk vs. soy proteins would support protein accretion (i.e., muscle hypertrophy). Subjects performed an intense workout on only one of their legs to isolate the effects on exercise to a single muscle mass. Immediately following exercise, subjects consumed an isonitrogenous (18.2 grams of protein) and isoenergetic (750 kilojoules) beverage of either low-fat milk or a beverage that contained hydrolyzed (partially pre-digested) soy proteins as a protein source. The investigators observed that the soy promoted a more rapid and transient hyperaminoacidemia than milk. Nevertheless, over the ensuing three hours following resistance training they observed a markedly greater uptake of amino nitrogen following milk consumption. In other words, milk protein was more effective at supporting muscle protein anabolism. The second study by Dr. Phillips and colleagues wished to test their finding of greater post-exercise anabolic response acutely following resistance training in a chronic resistance training setting.2 The subjects always exercised at least two hours post-prandial (after eating) and in the post-exercise period consumed one drink immediately and a second drink one hour later. The increase in muscle fiber cross sectional area was slightly greater in the milk-consuming group than the other two groups, so Dr. Phillips’ short-term findings were borne out when a long-term comparison was made. The authors concluded: “Our findings revealed that even when balanced quantities of total protein and energy are consumed, milk proteins are more effective in stimulating amino acid uptake and net protein deposition in skeletal muscle after resistance exercise than are hydrolyzed soy proteins… In young men completing 12 weeks of resistance training (five days per week) we observed a tendency (P = 0.11) for greater gains in whole body lean mass and greater muscle fiber hypertrophy with consumption of milk.” Macronutrients and Testosterone Janne Sallinen and co-workers at the University of Jyväskylä in Finland examined the relationship between macronutrient intake and blood anabolic hormones.3 In the first part of this study, blood basal anabolic hormone concentrations and macronutrient intake were examined in the total group of subjects. In the second part of the study, a subgroup of five gym rats and five physically active non-athletes performed high-volume and high- intensity heavy resistance training. The main finding of this study was that the basal testosterone level correlated with intake of fat (saturated and monounsaturated fatty acids) and negatively with protein, protein/fat, protein/carbohydrate and carbohydrate/fat ratios. However, when the two groups were examined separately, the significant relationship between macronutrient intake and testosterone could be noticed in the strength athletes only. No relationship between the biologically active (free) testosterone or growth hormone and macronutrient intake were observed in this study. This study also showed that testosterone responses to heavy resistance training may be influenced by macronutrient intake. Both total testosterone and free testosterone responses to training were significantly correlated with total fat, saturated fatty acids, monosaturated fatty acids and negatively with protein, protein/fat, carbohydrate/fat and protein/carbohydrate ratios. The authors concluded, “The present nutritional data in relation to [blood] basal testosterone concentration and [blood] total and free testosterone responses to [heavy resistance training] suggest that the moderate intake of both fat and protein could be recommended for strength athletes.” In other words, low-fat or very-high-protein intake may have adverse effects on testosterone levels. Contrary to popular belief, saturated fats are not that bad. If saturated fatty acids were of no value, or were as harmful to humans as the AHA Nutrition Committee claims, evolution would probably not have established within the mammary gland the means to produce saturated fatty acids that provide a source of nourishment to ensure the growth, development and survival of mammalian offspring.4 The recent literature review by Drs. Bruce German and Cora Dillard at the University of California, Davis, stated, “The question remains: What is an appropriate amount to which saturated fatty acids in the diet can be lowered for optimal health? Before recommendations are made to further lower the content of these components in the food supply, should we not wait until scientific evidence clearly shows that this is the healthiest direction to take?”4