Vegan weightlifting: what does the science say?

MANY WEIGHTLIFTERS THINK A VEGAN DIET might be detrimental to their efforts because of the lower protein content of a typical vegan diet. Other weightlifters feel that a vegan diet enhances their training regimen by reducing fatigue and improving general health. Unfortunately, there are no studies looking directly at vegan weightlifters, but there is a fair amount of research that can be used to extrapolate to vegans.

While reading this article, keep in mind that weightlifting can be divided into two types:

* BODYBUILDING to achieve the most noticeable muscles.

* POWERLIFTING to produce the largest amounts of strength.

ENERGY

Carbohydrates, fat, protein, and alcohol all provide energy. Resistance training, exercises where muscles push or pull against some force, is used to develop and maintain muscular strength and requires an increase in energy above that of sedentary individuals. The amounts vary depending upon training regimen, as well as other factors, including exercise efficiency, gender, non-exercise habits, and genetics. Because of the variation in needs, there is no one easy formula for caloric requirements; it is a matter of experimentation.

It is important to note that not eating enough calories to meet needs will tend to reduce muscle mass. Eating adequate calories spares muscle protein that would otherwise be used for energy. Paying attention to hunger signals can be a good guide in knowing whether you are eating enough energy. For a general ballpark figure, novice male weightlifters increased muscle mass and size, and lowered body fat, on a diet of about 18 calories/lb of body weight per day (3240 calories/day for a 180-lb person). (1) In another study, highly trained male bodybuilders ate 22.7 calories/lb (4,086 calories/day for a 180-lb person). (2)

PROTEIN

Depending on the source, protein needs among weightlifters are reported at values equal to the Recommended Dietary Allowances (RDA) to values as high as four times the RDA (Table 1). During the 1800s, it was believed that protein was the main fuel used during exercise. But work in the early part of the 1900s indicated that exercise did not change protein needs and, until the 1970s, was accepted without further research. (3) Recently, there has been more research on protein requirements of athletes, with varying interpretations.

Determining how much protein a person needs is often done by using nitrogen balance studies. Nitrogen is a component of amino acids, the building blocks of protein, and can serve as a marker for protein metabolism. Positive nitrogen balance means that the person is taking in more nitrogen than he or she is excreting, and is therefore using that nitrogen to build muscle. Negative nitrogen balance means more nitrogen is being excreted than consumed, and thus muscle is breaking down. When looking solely at athletic performance, nitrogen balance is an indirect method of measuring protein needs; what really matters is whether the person increases muscle mass, strength, or speed.

Two studies are particularly relevant. Lemon et al. studied 12 men starting an intensive weight training program of 1.5 hours, six days a week. (1) They compared one month of supplementing with carbohydrates (on a diet of 1.4 g/kg of protein per day) to one month of supplementing with protein (for a total of 2.6 g/kg of protein per day) for the same people. They determined that a protein intake of 1.6 to 1.7 g/kg was needed to achieve nitrogen balance. However, muscle size and strength increased the same amount on both regimens. The authors thought that extra amino acids for the muscle-building during the carbohydrate treatment were coming from amino acid pools found in the digestive tract, kidneys, or liver. These sources are small and will eventually be depleted.

The second study was conducted by Tarnopolsky et al. on six lacto-ovo vegetarian bodybuilders who had been training intensively for at least three years. (2) The bodybuilders normally ate 2.77 g/kg of protein. Upon reducing their protein "intake to 1.05 g/kg, the group remained in nitrogen balance and changes in lean (non-fat) body mass did not occur. Two individuals, however, were found to have a negative nitrogen balance while eating 1.05 g/kg of protein. These results indicated that protein needs for the majority of advanced bodybuilders are fairly close to 1.05 g/kg but that some may have higher requirements.

Taken together, these studies on a small number of athletes imply that protein needs (per body weight) may be greater in the beginning stages of training (when muscles are making larger increases and protein is deposited) than when muscle mass has plateaued.

The Food and Nutrition Board, which sets the RDA, reviewed Lemon et al.'s study and others and concluded there is no sufficient evidence to support that resistance training increases the protein RDA of .80 g/kg for healthy adults.

Some vegan health professionals have recommended slightly higher protein intakes (.9-1.0 g/kg of body weight) than the RDA for vegans in general. (5,6) However, the Food and Nutrition Board recently said that if complementary sources of protein are used (generally mixing beans and grains throughout the day), vegetarians' protein needs are no greater than non-vegetarians. (4) It should be noted that the RDA for protein has a margin of safety such that many sedentary adults meeting the RDA will actually get more protein than they need. Considering the information reviewed above and the lack of other specific research, it seems reasonable to conclude that the protein needs of most vegan bodybuilders are somewhere between .8 and 1.5 g/kg (.36 and .68 g/lb) of body weight.