Soy & Whey Diets

Soy and whey diets may be useful to help reach various goals, such as weight-loss and bodybuilding, and for health concerns including menopausal symptoms, cardiovascular health and high cholesterol. Adding soy and whey products can supplement the protein in your diet without the addition of excessive fat from meat. Also, soy products are a good substitute for dairy products if you are lactose intolerant.

Identification

Protein is broken down into amino acids in the body. Of the 21 kinds of amino acids, the body makes 11; the remainder of these "essential" amino acids must be obtained from food. Most vegetable proteins are incomplete proteins but whey and soy protein contain all 10 essential amino acids. Whey protein, derived from one of the proteins in cow's milk, is a byproduct of cheese-making. Whey can contain up to 75 percent lactose, says NoWhey.org.

Soy protein is made from soybean, specifically soy flour. It is produced in three ways. Protein isolate is the most refined form. Protein concentrate is soybean without the carbohydrates. Textured soy, often called TSP, is used as a meat replacement or additive in vegetarian products such as soy burgers, cheese, soy yogurt and soy dogs.

Protein Content

Protein is essential for healthy skin, bones, muscles and organ tissue. MayoClinic.com suggests that 10 to 35 percent of total daily calories should come from protein, which amounts to 50 to 175 g based on a 2,000-calorie diet. Endurance and strength-training athletes need more. Whey protein powder contains 29 g of protein per 30 g scoop, with 116 calories and no fat, according to calculations on the MyFitnessPal website. Soy protein powder contains 11 g of protein per 30 g, with 2 g fat and 120 calories.

Benefits of Whey

A study done at the University of Wollongong, Australia, found that the type of protein in a diet has a significant effect on weight. Whey protein was found to be the most effective of various protein sources tested in stabilizing weight gain and body mass. Whey had the strongest effect on decreasing appetite and stimulating a high production of adiponectin, which regulates metabolism of fat, and was associated with the lowest insulin levels, as published in "Nutrition & Dietetics" in June 2008.

Benefits of Soy

Soy protein may be beneficial in lowering cholesterol. An association with soy and changes in serum lipid concentrations was made in a 1995 study published in "The American Journal of Clinical Nutrition." The conclusion was that soy protein consumption lowered levels of total cholesterol, including LDL, the "bad" cholesterol, without significantly lowering levels of HDL, or good, cholesterol.

Comparison

Many athletes favor whey protein because they feel soy is inferior in promoting muscle weight gain. A direct comparison study was published in 2004 in "Nutrition Journal" that examined the effects of soy versus whey protein bars on lean body mass and antioxidant capabilities. Findings were that both whey and soy protein bars showed a larger gain in lean body mass than the control group, but the soy was superior in preserving two aspects of antioxidant function.