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Whey and extra leucine helps build muscle during weight loss

A goal of any weight loss program is to maximize fat loss while preserving or even building muscle mass. This is especially important in older individuals who carry extra weight because they are at increased risk of low muscle mass and are not as responsive to protein as younger individuals.

Two strategies to protect muscle during weight loss are to take whey protein and to perform resistance training. Researchers in the Netherlands tested both approaches in obese men and women who restricted energy intake by 600 kcal/day and performed resistance training (3 times per week) for 13 weeks. 

One group received a carbohydrate-based beverage with no protein containing 150 kcal. Another group received a 150 kcal beverage that contained 21 grams of whey protein plus extra leucine (total 2.8 grams). Leucine is a naturally occurring amino acid in protein food, but it is particularly high in whey. A small amount of leucine was added to the whey to bring the total to 2.8 grams per serving. All participants consumed the beverages in the morning before breakfast, as well as after each training session for a total of 10 servings per week.

The whey group lost slightly more body weight (-7.5 vs -6.2 pounds) and body fat (-7 vs -5.5 pounds), but these changes were not statistically different between groups. However, the whey group gained muscle mass (0.9 pounds), whereas the carbohydrate group lost muscle mass (-1.1 pounds). These findings underscore the beneficial effects of whey protein and adequate daily consumption of leucine in order to preserve muscle mass during weight loss. 



If you primarily consume plant proteins or are a vegetarian, realize that plant proteins contain about half the level of leucine as whey protein. Leucine is probably the most important amino acid to turn on the body’s switch to activate protein synthesis. Prior studies have shown one needs to consume about twice as much plant protein to equal the same muscle-building effects as whey protein. This double dose of plant protein essentially provides about 2.5-3g of leucine, the amount needed to build muscle. One might consider adding leucine to plant proteins to boost their muscle building potential when taking less than 40-50 grams, or adding leucine to a whey protein shake when consuming less than 25-30 grams of protein. 

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