Many diet products have used the alleged fat blocker chitosan, but recent studies suggest they have very little effectiveness. The active ingredient in many products is chitosan, a fibre extract that comes from the shells of shrimp and other crustaceans. The chitosan in theory bonds with fat from foods and stops it being absorbed, acting like a sponge to soak up to six to ten times its own weight in fats. In theory, the dietary fat instead will be disposed of in the stools without being stored as body fat. Adherents claim it increases feelings of fullness as well and allegedly results in eating some 15% less food in subsequent meals. By slowing transit, it also allegedly lowers the glycemic index of foods, an effect which makes sense to us, but which is not documented.
Small-scale trials in animals in the 1990s showed this product resulted in weight loss, leading to much media hype and a proliferation of products using chitosan (Lipoclear being one of the most popular in the UK, though no longer availble). However, further scientific research suggests that these claims are without substance. The British Advertising Standards Authority has upheld complaints about chitosan products advertised by eight companies. Likewise, the US Food and Drug Administration has issued warning letters to several companies who make claims that are not supported by reliable scientific evidence about the benefits of chitosan as a fat blocker.
One small study has found that the amount of fat actually removed by chitosan is insignificant. The study involved 15 men who consumed five meals per day for 12 days with a daily total of about 25 grams of fat. The amount of fat excreted during four days when they took chitosan was then compared to the amount excreted without chitosan. Taking 10 capsules of chitosan per day increased fecal fat excretion by only about 1 gram--a mere 9 calories worth. If this study is correct, you'd take 277 days and 2770 tablets to lose a single pound (2500 calories) using Chitosan!
Oddly, Chitosan's main ingredient is also used in many other applications, ranging from a natural seed treatment and plant growth enhancer to use in water filtration.
Ill Effects: A common side effect is indigestion and bloating. Also some people find it very difficult to pass stools when using the product, as they can become quite hard. Needless to say, you shouldn't take Chitosan if you have any shellfish allergies. And as with all diet pills, you shouldn't take them if you are pregnant or breastfeeding.
Even though the reported side affects appear mild, we'd pass on Chitosan and choose a weight loss supplement with a real, scientific trial-based track record.
Prices: Chitosan is available from Healthy Direct (which has the best prices for weight loss supplements in our experience) in a generic formulation for £7.99 for 180 tablets, or £12.99 for 360 tablets.
One month's supply works out to £12.99 (you're supposed to take two tablets per meal, and this is caculated using the bulk option).