Soy isn't exactly at the top of most bodybuilders' list of must-eat proteins. Okay, sumo wrestlers eat the stuff by the bucketful, but then again, unless your goal is to be 400 pounds and knock heads with another big guy in a G-string, perhaps it seems unappealing. But there may be something to this soy stuff. Proteins such as whey have bioactive peptides; that is, smaller amino acid units within the protein may confer specific biological properties in and of themselves. For instance, if you look at milk protein, you'll find several smaller proteins that might have immunity-enhancing properties, including immunoglobulins, kappa-casein, lysozyme, lactoferrin, haptocorrin, alpha-lactalbumin and lactoperoxidase.
What if we could isolate certain peptides, or small proteins, from soy? A group in Japan did just that. Soy protein isolate hydrolysate (SPI-H) was made by hydrolyzing soybean protein isolate with protease (an enzyme that breaks down protein) from Bacillus subtilis; the average peptide chain length was five to six amino acids. Those are very short peptides.
They compared the effects of SPI-H to casein protein on metabolism in diabetic mice. First, they gave the mice unrestricted access to a high-fat diet (30 percent fat'I guess that's a lot of fat for mice) for four weeks. After that they divided the mice into two groups and put them all on restricted-calorie diets, with both groups getting the same amount of protein and fat (35 percent protein, 5 percent fat), to see how that would affect energy expenditure, bodyfat and bodyweight. The only difference was that one group got the soy peptides, and the other group got casein.
Bodyweight and fat levels decreased the same in both groups, so at the gross level no major changes occurred. Remember, it was a short study (four weeks).
Even so, energy expenditure after eating, or the thermic effect of food, was 1 to 8 percent higher in the SPI-H group. That's equivalent to a 25 percent increase in resting metabolic rate. Now here's the cool part: Much of that difference in metabolic rate was due to the fact that SPI-H promoted a much greater increase in carbohydrate oxidation'meaning those mice burned many more carbohydrate calories. Interestingly, the casein group burned proportionately more fat. But when you take the total, the net effect was greater in the SPI-H group because they burned a helluva lot more carbs than the amount of fat the casein group burned.
It would be interesting to see if scientists could isolate which components of casein promote fat oxidation and which components of soy promote carbohydrate oxidation. Is there a particular peptide that does that? Could you combine the two proteins to maximize the burning of both carbs and fat?
Either way, the study puts a twist into the protein debate: whey vs. casein vs. soy. Which is best?
Bitter melon burns fat. The bitter melon is widely used as food as well as medicine in Asia. Some research indicates that it's good for blood sugar metabolism and may in fact reduce bodyfat. So you better go to your local market and get your bitter melon stash! Actually, bitter melon, known scientifically as Momordica charantia, has some good supportive data. Researchers at the University of Hong Kong gave bitter melon to rats that they put on a high-fat diet to induce diabetes. Bitter melon was fed freeze-dried as a percentage of the diet (ranging from 0.75 percent to 1.5 percent bitter melon). At the highest dose rats tended to have less organ fat mass and were less energy efficient'meaning they burned more energy. Also, bitter melon supplementation improved insulin metabolism while lowering serum insulin, but, oddly, it raised fat levels in the blood.
It isn't known how bitter melon could lower bodyfat levels. Some think that it suppresses lipogenesis and promotes lipolysis. Either way, maybe bitter melon should be a normal part of your nutritional regimen.
A thermogenic stack. Imagine chewing gum that contains a caffeine/nicotine stack. Well, leave it to Danish scientists to give this one a shot. In a randomized, double-blind, placebo-controlled trial they compared the thermogenic responses of seven different kinds of chewing gum (I can see the Doublemint twins commercial already). They used 12 healthy men of normal weight who were 18 to 45 years old. These were the doses studied (milligrams of nicotine/milligrams of caffeine): 0/0, 1/0, 2/0, 1/50, 2/50, 1/100, 2/100.
The thermogenic responses were 3.7 percent, 4.9 percent, 7.9 percent, 6.3 percent, 8.5 percent and 9.8 percent for gums containing 1/0, 2/0, 1/50, 2/50, 1/100, and 2/100. Adding caffeine to one and two milligrams of nicotine definitely enhanced thermogenesis. But changing the caffeine dose from 50 to 100 milligrams did not have an effect. Both glucose and fat oxidation increased equally. And side effects occurred only in the two-milligram-nicotine group.
Bottom line: Combining one milligram of nicotine with 50 to 100 milligrams of caffeine may actually be a fairly potent thermogenic stack. Not that I recommend getting addicted to nicotine; but then again, how many of us are addicted to caffeine?
Ishihara, K., et al. (2003). A soybean isolate diet promotes postprandial carbohydrate oxidation and energy expenditure in type II diabetic mice. J Nutr. 133:752-757.
Chen, Q., et al. (2003). Bitter melon (Momordica charantia) reduces adiposity, lowers serum adiposity, lowers serum insulin and normalizes glucose tolerance in rats fed a high-fat diet. J Nutr. 133:1088-1093.
Jessen, A.B., et al. (2003). Effect of chewing gum containing nicotine and caffeine on energy expenditure and substrate utilization in men. Amer J Clin Nutr. 77:1442-1447.
Editor's note: Jose Antonio, Ph.D., CSCS, earned his doctorate at the University of Texas Southwestern Medical Center. He is a co-editor (with Jeffrey R. Stout, Ph.D.) of and contributor to Sports Supplements (Lippincott Williams & Wilkins), Sports Supplement Encyclopedia (Nutricia), Supplements for Strength-Power Athletes (Human Kinetics) and Supplements for Endurance Athletes (Human Kinetics). For more information visit www.supplementbooks.com. IM