Evidence Level
Moderate
White kidney bean extract has moderate evidence as a starch blocker, with a meta-analysis showing significant body fat reduction. It works specifically on starch (complex carbohydrates) — it does not block sugar, fat, or protein absorption. The GI side effects (gas, bloating) result from undigested starch being fermented by colonic bacteria. It is most useful for individuals who consume significant amounts of starchy foods and want to reduce carb-derived calorie absorption.