by Steelhead » Fri Aug 03, 2012 3:42 pm
Without bragging about my own athletic success, I will share some science that hopefully will help motivate everyone to not hold back on following Dr. McDougall's suggested dietary program while endeavoring to attain athletic success.
The key principles regarding athletic prowess are (1) genes and (2) hard work (not necessarily in that order). The goal is to maximize our genetic potential through training. As many of us have discovered, we don't really need to eat all that much to be energetic and fit, but we do need glycogen and that comes from carbohydrates (including importantly starches).
A real benefit for the athlete on this type of eating program is that we get our energy from carbohydrate and don't need to use protein as an energy source; hence, we don't need that much protein for building tissue.
If we take the recommended energy intake in calories for each age group, say 2500 C for the average adult male, and calculate the percentage of this value that the RDA for protein supplies, the values approximate 10 percent for each age group. The National Academy of Sciences indicated that the AMDR (Acceptable Macronutrient Disribution Range) should not be set below levels for the RDA for protein, which is about 10 percent of energy. Mathematically, 56 grams of plant-based protein, at 4 Calories per gram, total 224 Calories, which is about 9-percent of 2,500, or near the lower limit of the AMDR. (It is easy getting 56 grams or more from a plant-based diet - stating the obvious and preaching to the choir.)
Consequently, protein needs are determined by overall food energy intake. If energy intake is inadequate, such as may be the case in those on weight-loss diets or the elderly, dietary protein may be used for energy instead of its core purpose of building tissue. (This is why this is not a calorie-restricted diet even though it appears that some still count calories and focus on losing muscle mass and water instead of burning fat and gaining muscle mass -- that is, throw the scale away and buy a measuring tape.)
Hence, if the active individual desires to maintain lean body mass, it is essential to have not only adequate protein (from plant sources is fine), but also sufficient carbohydrate Calories in the diet to provide a protein sparing effect. In other words, our plant-based, high starch diet, is brilliant for the athlete: carbohydrate Calories will be used for energy production, thus sparing utilization of protein as an energy source and allowing it to be used for its more important structural and metabolic functions. The presence of adequate muscle glycogen inhibits enzymes that catabolize muscle protein -- thereby reducing the amount of necessary dietary protein compared to the low-carbohydrate diet leading to decreased muscle glycogen levels leading to increased dependence upon protein as an energy source (a bad thing).
I don't have the exact reference, but recall that scientists at the University of Maastricht in the Netherlands noted that high-carbohydrate diets have a protein-sparing effect for endurance athletes.
Moreover, protein metabolism becomes more efficient as a result of training: the response of muscle protein turnover to habitual exercise is comparable to other metabolic changes in the muscle associated with exercise training. Although an initial bout of exercise may markedly elevate protein breakdown and synthesis in an untrained individual, the effect is much less in one who has trained habitually. Training induces a decreased activity in BCAAD, the enzyme that oxidizes BCAA (Branch Chained Amino Acid), when exercising at a standardized workload of the same absolute intensity! Trained individuals, during rest after exercise, have been shown to experience a preferential oxidation of fat and a sparing of protein. This is why in pertinent part a high starch, low protein, low fat diet, with exercise burns off our fat and makes us lean.
In its recent Dietary Reference Intakes for protein, the National Academy of Sciences concluded that in view of the lack of compelling evidence to the contrary, NO additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise. Some investigators even contend that because exercise training increases the ability of the body to retain protein in the recovery period, athletes in training may need less protein than sedentary individuals if they consume enough Calories to maintain body weight.
So I expect everyone eating as recommended by Dr. McDougall who embarks on an athletic program will experience great success -- and will recognize the brilliance of eating correctly when it comes to athletic success.
Just do it.
No matter what genes we inherit, changes in diet can affect DNA expression at a genetic level." Michael Greger M.D.
Certificate in Plant-Based Nutrition - eCornell & T. Colin Campbell Foundation.