Shellfish Extract Linked To Weight Loss

Chitosan, an extract of lobster, shrimp and crab shells, has been acclaimed for helping people peel off pounds. But does the proof merit the praise? Some evidence says no, some says yes.

Test-tube research implies that the chitosan molecule and fat stick together as effectively as Velcro, suggesting that fat is then expelled in stools. However, in a recent study, 88 overweight Asian women and men took chitosan supplements (Absorbitol) for four months without changing their diets. The results showed no greater changes in body weight, leanness or blood pressure than in the placebo group. This finding supported two other studies—one lasting a month, the other lasting six months (the longest study to date)—which also found no impact on body weight. The six-month study, which employed a 1,000-calorie per day diet, also found that both the chitosan and placebo groups lost similar amounts of muscle.

Another very recent study, however, found a specific brand of rapidly soluble chitosan (Chitosol) to produce significantly greater weight loss than placebo. While more research is necessary to be certain about the benefits of chitosan, it's important to recognize that not all chitosan products may be alike. Regardless, the benefits appear to come only from a processed shell extract, so bingeing on crab legs won't tip the scales in your favor.

Nutrition and exercise biochemist Anthony Almada, MS, has collaborated on more than 45 university-based studies and is founder and chief scientific officer of IMAGINutrition.