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Weight Loss
Peter Tallas, Ph.D., C.N.S., L.N. Senior Scientist, Nutrition Research, Douglas Laboratories
For many people, losing body weight is crucial for improving self-esteem. Dieting has become a national preoccupation, with a seemingly never-ending series of videos, books, and newspaper articles about diets and exercise regimens. The food industry has fed the trend with an ever expanding array of low calorie and low fat entrees, nutritionally complete beverages, food bars, and snack products intended to help in the quest to lose weight and improve body image. Excess weight loss is important not just for cosmetic reasons, but is also important for reducing the risk of numerous diseases, including type 2 diabetes mellitus, cardiovascular disease, gall bladder disease, high blood pressure, and osteoarthritis. Ironically, while this desire to lose weight is pervasive in today's culture, the number of overweight and obese individuals has increased by 25% over the last 30 years and continues to increase among both adults and adolescents. Indeed, currently over half of all U.S. adults are considered overweight, a characteristic of an affluent society marked by sedentary lifestyles and over-consumption of high-fat foods.
The degree to which a person is overweight is defined by the body mass index (BMI), which is calculated by dividing weight in kilograms (kg) by height in meters square, (kg/m 2 ). BMI is highly correlated with body fat content. For example, a woman who weighs 160 lb. and is 5 feet, 6 inches tall has a BMI of 25.9. Both the World Health Organization and the National Heart, Lung, and Blood Institute consider a BMI of 25.0 - 29.9 to be overweight or pre-obese.
Excess weight is typically caused by increased energy consumption coupled with decreased energy expenditure. One way to correct this imbalance is to limit high caloric, high fat intake and/or to increase exercise. Dietary supplements can also help. For example, Chitosan, a natural product produced from the chitin of crab shells, inhibits the absorption of dietary fat.
Additionally, numerous dietary supplements may directly affect fat metabolism. Inhibition of lipid synthesis by (-) hydroxycitric acid (HCA) derived from Garcinia cambogia, may inhibit fat formation and deposition. Herbal products containing ephedra may increase energy expenditure by stimulating the basal metabolic rate via the sympathetic nervous system and supplemental chromium may increase lean body mass and decrease body fat.
Garcinia cambogia
Garcinia cambogia, also known as Malabar tamarind or Brindall berry, is a native fruit of South India. This orange-sized yellowish fruit is used not only in the preparation of Indian curries, but also in Ayurvedic medicine to treat obesity. Garcinia cambogia's high content (20 - 30% in the dried fruit and rind) of the organic acid (-) hydroxycitric acid (HCA) is thought to be responsible for its effect in promoting weight loss.
HCA is a competitive inhibitor of the extra mitochondrial enzyme adenosine triphosphate (ATP)-citrate lyase. Inhibition of this enzyme effectively limits the amount of precursor, acetyl coenzyme A, available for fatty acid and cholesterol synthesis in the body. A significant amount of the acetyl-CoA used in fat synthesis comes from mitochondrial oxidation of pyruvate that originates from dietary carbohydrates. However, before fat synthesis can proceed, the precursor acetyl CoA must pass out of the mitochondria into the cytosol where it can be synthesized into fat. Citrate is the carrier thattransports the acetyl unit across the mitochondrial membrane into the cytosol where ATP-citrate lyase cleaves it, producing acetyl-CoA for fat synthesis. Thus, inhibition of the enzyme that cleaves citric acid in this shuttle between the mitochondrion and the cytosol should effectively limit fat synthesis.
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