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BCAAs, Grapefruit and Fat Dogs

The amount of scientific data on sports nutrition and supplementation is growing faster than a breast-feeding infant. If you blink, you’re already falling behind on the latest research. Never fear: I’m here to give you some of the newest cool tidbits from the world of science.

You’ve heard how great the branched-chain amino acid leucine is for muscle building and alleviation of soreness. Well, another BCAA, isoleucine, may indeed have its own special properties. Mice given isoleucine had an almost 6 percent lower bodyweight gain and 49 percent less epididymal white adipose tissue mass—that is, fat—than control mice. Also, insulin and muscle fat were lower in the isoleucine-fed mice. Perhaps it’s time to increase your intake of BCAAs.1

Ever eat grapefruit? Yes, it’s sour and nasty, but scientists have characterized something called nootkatone, a constituent of grapefruit, as a naturally occurring AMPK activator. Nootkatone—say that three times fast—sounds like the name of an Eskimo. Nonetheless, long-term intake of diets containing 0.1 to 0.3 percent nootkatone significantly reduced high-fat and high-sucrose diet-induced bodyweight gain, abdominal-fat accumulation and development of hyperglycemia, hyperinsulinemia and hyperleptinemia in mice. Furthermore, endurance capacity, evaluated as swimming time to exhaustion, was 21 percent longer in mice fed nootkatone than in control mice. So nootkatone is beneficial in preventing obesity and improving exercise.2 Maybe we need to eat more grapefruit.

Got a fat dog? Or a fat pet of any kind? A new study tested the effects of a high-protein, high-fiber diet on 15 fat dogs. Fifteen dogs ate that kind of diet, while a matched control group of 27 dogs got a high-protein, medium-fiber diet that contained an equal number of calories. They found that Fido’s percentage of bodyfat mass decreased with the high-fiber version.3 Believe it or not, that diet works for the dog’s owner too.

If you want to have fit kids, what diet is best for them? Well, the worst is a low-protein, high-glycemic-index diet, which actually makes them fat. The best diet for kids is a high-protein, low-glycemic-index diet. That combination was protective against obesity in children in a recent study.4 And guess what—it works in adults too.

Finally, in the battle between animal and plant sources of protein, we know that when it comes to anabolic effects, animal-based protein wins. A recent study compared the effects of high-protein meals containing meat, dairy and soy sources on energy expenditure, substrate oxidation and satiety of 12 adults during eight-hour stays in a whole-room calorimeter. The three isoenergetic high-protein test meals—30 percent protein, 40 percent carbohydrate, 30 percent fat—contained predominantly meat, dairy and soy protein. Protein oxidation was significantly lower in meals dominated by meat, meaning that their protein-sparing effect was great relative to the retention of lean body mass.5

—Jose Antonio, Ph.D.


Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (; also check out his site


1 Nishimura, J., et al. (2010). Isoleucine prevents the accumulation of tissue triglycerides and upregulates the expression of PPARalpha and uncoupling protein in diet-induced obese mice. J Nutr. Mar. 140(3):496-500.

2 Murase, T., et al. (2010). Nootkatone, a characteristic constituent of grapefruit, stimulates energy metabolism and prevents diet-induced obesity by activating AMPK. Am J Physiol Endocrinol Metab. 299(2):E266-275.

3 German, A.J., et al. (2010). A high protein high fibre diet improves weight loss in obese dogs. Vet J. 183(3):294-297.

4 Papadaki, A., et al. (2010). The effect of protein and glycemic index on children’s body composition: The DiOGenes randomized study. Pediatrics. 126(5):e1143-1152.

5 Tan, S.Y., et al. (2010). Energy expenditure does not differ, but protein oxidation rates appear lower in meals containing predominantly meat versus soy sources of protein. Obes Facts. 3(2):101-104.


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