Weight loss is actually a misnomer because by weight loss we really mean fat loss. The problem with low calorie diets and aerobic exercise, the modus operandi of most people wishing to lose fat, is that they cause significant reductions in the amount of skeletal muscle. In fact on a typical forced calorie restriction diet, the average weight loss includes 50 % of that weight as muscle. The main problem with this is two fold. Firstly, muscle mass is what gives us shape, and so losing mass causes a deterioration in body shape and composition. Secondly, the reduction in muscle mass causes a concomitant reduction in resting metabolic rate, and this increases the risk of future weight gain. This last point is pivotal, because it is the main reason so many weight loss diets fail. As resting metabolic rate falls, the amount of energy required to sustain the organism declines. When the low calorie diets ends, the individual is at increased risk of weight gain because the original calorie intake is now too great for their newer lower resting metabolic rate.
The fall in resting metabolic rate caused by low calorie diets and aerobic exercise is detrimental to the health because muscle mass is inversely related to mortality, particularly in the elderly. Losing weight in the form of fat and muscle and then regaining weight in the form of fat is common in serial dieters, and results in a slow deterioration in body composition. Such yo yo dieting is the main reason most fail in their fat loss efforts. The trick to successful long term fat loss is to consume high quality foods that negate the need to cut calories. This is because high quality foods address the underlying cause of weight gain which is the consumption of low quality foods that damage the metabolism through the development of insulin resistance. Another key factor in successful long term fat loss is the maintenance or increase of skeletal muscle mass. Once yo yo dieting has damaged the resting metabolic rate, increases in skeletal muscle mass are the only way to return resting metabolic rate to its previous homeostatic levels.
In order to be able to increase skeletal muscle mass, it is important to eat enough high quality protein. High quality protein contains all of the essential amino acids in their correct ratios for metabolic needs, and this generally means consumption of proteins of animal origin. Few plant proteins are of high enough quality individually, the exception being the protein derived from the soya bean. High protein diets provide the body with a positive nitrogen balance, and this is pivotal to muscle protein synthesis, although added dietary protein also decreases the rate of skeletal muscle catabolism. This is especially true during periods of resistance training, the result of which produces an anabolic environment that favours the accruing of skeletal muscle mass. Whey protein is a popular dietary supplement with athletes because it is easy to digest, readily absorbed and has been shown to increase plasma levels of a number of amino acids pivotal to skeletal muscle growth, including the branched chain amino acids valine, isoleucine and leucine.
But how much whey protein is required to cause an anabolic response in terms of increasing myofibrillar muscle protein synthesis rates? Current recommendations are to consume around 1 gram of protein per pound of lean muscle tissue to maximise the growth seen from a resistance training programme. The amount of protein that should be consumed following a workout has also been investigated in the nutritional literature. For example, in one study1 researchers fed a group of healthy volunteers a high protein breakfast containing 0.54 grams per kg body weight protein, and three hours later the subjects performed 8 sets of 10 repetition leg presses and leg extensions at 80 % of their 1 repetition maximum. The subjects then consumed 0, 10, 20 or 40 grams of whey protein isolate immediately following training. The results showed that myofibrillar protein synthesis rates increased by 49 % and 56 % with ingestion of 20 and 40 grams of whey protein compared to the control and 10 gram whey protein ingestion.
Dr Robert Barrington’s Nutritional Recommendation: These results suggest that both 20 and 40 grams of whey protein after a workout are suitable for stimulating myofibrillar muscle protein synthesis. However, with the 40 gram dose, there was evidence of increased oxidation of amino acids and increased ureagenesis (increased nitrogen excretion in the urine) and therefore this higher dose there may have oversupplied protein for immediate metabolic needs. For the 80 kg subjects in this study then, the idea amount of protein for stimulation of myofibrillar protein synthesis is indicated to be 20 grams of whey protein isolate. As well as the recommendation to consume 1 gram per pound of lean body weight, it is also therefore prudent to ensure that 0.25 grams of high quality whey protein isolate are consumed following a workout. The rest of the protein intake should be spread throughout the day into 20 gram servings to minimise oxidation of the ingested amino acids.
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