Objective: Few weight loss supplements are clinically tested for efficacy, yet their proliferation continues. Chitosan-based supplements are sold as fat trappers and fat magnets. They purportedly block fat absorption and cause weight loss without food restriction. We quantified the in vivo effect of a chitosan product on fat absorption.
Research methods and procedures: Participants (n = 15) consumed five meals per day for 12 days. Energy intake was not restricted. Participants consumed no supplements during a 4-day control period and two capsules five times per day (4.5 g chitosan/d), 30 minutes before each meal, during a 4-day supplement period. All feces were collected from days 2 to 12. Oral charcoal markers permitted division of the feces into two periods. The two fecal pools were analyzed for fat content.
Results: Participants were male, 26.3 +/- 5.9 years old, BMI of 25.6 +/- 2.3 kg/m(2). Subjects consumed 133 +/- 23 g of fat/d and 12.91 +/- 1.79 MJ/d (3084 +/- 427 kcal/d). Individual meals averaged 26.3 +/- 9.3 g of fat. With chitosan supplementation at 10 capsules/day, fecal fat excretion increased by 1.1 +/- 1.8 g/d (p = 0.02), from 6.1 +/- 1.2 to 7.2 +/- 1.8 g/d.
Discussion: The effect of chitosan on fat absorption is clinically negligible. Far from being a fat trapper, at 0.11 +/- 0.18 g of fat trapped per 0.45-g capsule or 1.1 g (9.9 kcal) fat trapped per day, this product would have no significant effect on energy balance. The fat trapping claims associated with chitosan are unsubstantiated.