What is chitosan and how effective is it for weight loss?

Written by , Last updated: November 13, 2014

Chitosan is a compound that is extracted from the hard shells of shrimps or other crustaceans. While chitosan has many different uses, it supposedly also helps limiting the amount of fat our bodies are able to absorb from the food we eat. Naturally, this would make a chitosan supplement a perfect candidate for inclusion in any weight loss program. In this article I will review the available evidence for the supposed weight loss effectiveness of chitosan. If it is effective, I will also try to shed some light on how big of a boost can you expect to get from it.

What is chitosan and how effective is it for weight loss?

Many manufacturers are using chitosan as an ingredient for different forms of weight loss supplements, sometimes throwing additional "effective" weight loss components into the mix. You can ingest chitosan in a form of capsules, pills or powders and since chitosan is supposed to bind to the fat contained in the foods you eat in your digestive track (which should prevent absorption) it is best to consume it with your meals. In theory everything sounds fine, but what does actual scientific research have to say about this?

Reviews of chitosan's effectiveness

While some companies selling chitosan supplements claim that it can cause up to 8% of body weight reduction in a manner of a few short weeks, clearly we need to look at some of the more independent research sources. This review of 14 studies has shown that chitosan lead to an average weight loss increase of 3.7 pounds (1.7 kilograms) over the course of four weeks.

But this is the average result, the trials that showed the biggest chitosan weight reduction were also of the lowest quality. I'm guessing they were poorly designed and/or that there was insufficient data available. When only the high quality studies are considered, the chitosan weight loss results were minimal and insignificant. Here is an example of a study that showed chitosan does not help reduce body weight at all.

Another study was done that looked at how much fat was excreted in fecal matter with or without taking a chitosan supplement. If chitosan actually blocks fat absorption more fat should be excreted. But this study also confirmed that chitosan has no effect on the amount of fat we can absorb from the food we eat. The currently available chitosan reviews are a bit contradictive, but a majority of them (at least the higher-quality trials) indicate that chitosan is ineffective for weight loss purposes.

Dosage and possible side effects

If you are an incurable optimist who chooses to believe that those trials of questionable quality still provide sufficient proof that chitosan can help you lose weight, you also need to know about the recommended dosage and possible side effects. Apart from very mild forms of stomach upset, constipation or gas, chitosan is not known to produce any significant side effects (but you do need to be careful if you have a shellfish allergy). The maximum daily tolerable amount or levels causing toxicity have not been established. I was able to find one recommendation of 1.35 grams of chitosan three times daily, but this is for people with renal failure who are undergoing hemodialysis. Since most supplements contain 250 or 500 milligrams per tablet or pill of chitosan, you can probably safely follow the recommendations of chitosan supplement manufacturers.


While some of the available scientific research about chitosan's effectiveness for weight loss might provide some unclear signs of hope, a majority of quality studies indicate that chitosan is not an effective weight loss supplement.

But if you are still willing to part with your hard-earned money and place it on an uncertain weight loss bet you should be fine in any case (chitosan causes no known serious side effects). Just don't expect a miracle (or even any significant results for that matter) from chitosan.

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