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WEIGHT LOSS (2)
Peter Tallas, Ph.D., C.N.S., L.N. Senior Scientist, Nutrition Research, Douglas Laboratories
Although Ayurvedic medicine has been aware for centuries of Garcinia cambogia's potential to combat obesity, Western science has only in the past thirty years recognized the anti-lipogenic properties of HCA, Garcinia cambogia's active ingredient. Animal studies in the 1970s tested the hypothesis that metabolic regulation by HCA of the pivotal lipogenic enzyme, citrate lyase, might be useful in treating lipid disorders. These early studies showed that oral administration of HCA markedly reduced lipogenic rates and circulating triglycerides in genetically obese rats. Hypertriglyceridemia and increased hepatic lipogenesis, induced by dietary fructose, were also significantly reduced by orally administered HCA.
In vitro rat studies in the 1980s reaffirmed hydroxycitrate's depressive effect on fatty acid synthesis from glucose and indicated the prime role the citrate cleavage pathway plays in the conversion of carbohydrate to fat. Cellular work in the 1990s tested HCA in a hepatoma line and found a strong inhibition of citrate carbon flux into fatty acids.
However, researchers studying HCA have found that although obese rats that were orally administered HCA reduced their food intake and body weight, their body fat percentages did not change. These studies suggest that combating obesity has to be waged on several fronts, and not just in a campaign of metabolic regulation of lipogenesis. The obese body seems to be well adapted to defending its composition.
Although several clinical trials evaluating the weight loss benefits of HCA have presented positive results, a recent clinical trial reported opposite findings; its design methodology, however, was significantly flawed. The twelve week, randomized, double blind, placebo-controlled trial was undertaken in an outpatient weight control research unit. All patients ate a low calorie, high fiber diet daily. Test subjects (66) also ate 1500 mg/d HCA. The investigators reported no difference in loss of weight or fat mass between the HCA group and placebo. Unfortunately, this trial was significantly flawed, as the authors essentially "stacked the deck" against HCA's action by feeding a high fiber, low energy, non-lipogenic diet, thus preventing much lipogenesis from carbohydrate to occur. The low calorie diet also precluded testing the hypothesis that HCA reduces feeding and curbs appetite. Also, a high fiber diet can limit HCA absorption, and hence limit its effectiveness.
Chitosan
Dietary chitosan, a glucosamine polymer derived from crab shells, has been shown to be not only an effective binder of dietary fat, but also a potent hypocholesterolemic agent. Thus, chitosan could be a potent player in a weight control program by reducing the absorption of dietary fat.
Rat studies undertaken twenty years ago demonstrated that the addition of 2 to 5% chitosan to a hypercholesterolemic diet significantly reduced plasma cholesterol 20 to 30%, without affecting food intake. Although higher dietary levels of chitosan further reduced plasma cholesterol, they had a depressive effect on growth. The chitosan in this study evidently reduced plasma cholesterol by binding intestinal lipids and increasing fecal excretion of both endogenous and exogenous choles-terol. Later investigation showed that chitosan binds both bile acids and phospholipids, reducing their absorption from the intestines.
Don't Forget Exercise
It is becoming increasingly apparent that the decreased level of physical activity associated with our Western lifestyle is a very important determinant of the "obesity epidemic" sweeping through the world today. Exercise may work on two fronts to battle this encroaching epidemic. First, increased physical activity will result in more calories being burned. As lean body mass expands, induced by muscular contraction, there is a concomitant increase in the daily thermogenesis of the metabolic rate. Highly active individuals may have a reduced appetite, and find energy dense foods less appealing.
Putting It All Together
In conclusion, dietary supplements can be a valuable part of a weight reduction program that combines lowered caloric intake with increased activity. In the effort to reduce energy intake, the first step is to wisely choose a less energy dense diet. Chitosan operates to reduce absorption of consumed fat, the most calorically dense food component. Garcinia cam-bogia can reduce the synthesis of new fat in the body, while ephedra may help to increase energy expenditure, by increas-ing metabolic rate as well as reducing appetite. Finally, chromium works to normalize carbohydrate, protein, and fat metabolism toward pre-ferential loss of fat rather than muscle protein.
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