The kidney bean is a variety of the common bean (Phaseolus vulgaris). It is named for its visual resemblance in shape and color to a kidney. Red kidney beans should not be confused with other red beans, such as adzuki beans.
White kidney beans are legumes native to Central and South America that prevent the breakdown and absorption of carbs and suppress appetite. In diet pills, the legume appears as Phaseolus vulgaris. When taken as part of a reduced-calorie diet, participants in a small study — published in 2014 in Obesity — lost 6 pounds over a 12-week period, compared to 2 pounds in the control group. However, a review study from 2011 published in the British Journal of Nutrition says much of the research on white kidney beans and weight loss are flawed, and recommends larger, more rigorous studies to figure out how well it works.