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15.09.2009

Thirty or ninety grams of meat protein: it makes no difference to muscle fibre production

Eat a piece of lean meat weighing 113 grams – which is good for 30 g of protein – and your production of muscle protein will increase just as much as after eating a piece of meat three times the size, write Texan researchers in the Journal of the American Dietetic Association. This makes the time-honoured theory, that you optimise muscle tissue manufacture by eating protein at several moments throughout the day, more likely.

The researchers gave two groups of test subjects – one with an average age of 34 and the other with an average age of 65 – a piece of meat at midday. Immediately after the meal and again at five o'clock in the afternoon, the researchers took a small sample of muscle tissue from the subjects’ bodies and measured the muscle protein production.

The results are shown below. The greyish bars in the background represent the measurements after consuming 90 g of meat protein. The transparent bars in the background represent the measurements after consuming 30 g of meat protein. The higher meat protein intake led to a slightly higher protein production, but the difference was not statistically significant.

The test subjects were healthy, but did not do any sport, and certainly no power sports. High-intensity muscular exertion, like weight training, boosts the anabolic machinery in the body's cells. The researchers therefore do not exclude the possibility that consuming a large amount of protein before or soon after a training session will lead to more increase in muscle mass than consuming smaller amounts.

The researchers deliberately withheld carbohydrates, and fed their subjects only proteins and a little fat. Carbohydrates increase the anabolic stimulus of food proteins, primarily because carbohydrates lead to a rise in insulin levels. The researchers excluded carbohydrates in their study to keep it simple, and elderly people react less well to insulin than young people. Elderly people also react less well to a low protein intake. If elderly people eat 7 g of protein their muscle tissue manufacture rises by less than that of young people.

"We suggest that instead of a single, large protein-rich meal, ingestion of multiple moderate-sized servings of high-quality protein-rich foods over the course of a day may represent an effective means of optimizing the potential for muscle growth while permitting greater control over total energy and nutrient intake", the researchers conclude.

Source:
J Am Diet Assoc. 2009 Sep; 109(9):1582-6.

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