This study found that supplementing with WKBE enhanced weight loss in the context of a hypocaloric diet, and a greater dose of WKBE led to greater weight loss.

WKBE promotes weight loss by inhibiting the digestion of carbohydrate. Specifically, WKBE contains the glycoprotein alpha-amylase inhibitor isoform 1, which inhibits the activity of alpha-amylase, an enzyme responsible for breaking down starch into simpler sugars, so that they can be absorbed by the body.

White kidney bean extract inhibits starch digestion to promote weight loss

White kidney bean extracts inhibits the activity of alpha-amylase, an enzyme that breaks down starch.

WKBE might also have an indirect effect on energy absorption by altering the composition of the gut microbiota,^[1]^[2] resulting in fewer calories being extracted from the diet.^[3]

The results of the summarized study are in agreement with previous research. One notable trial had 123 participants consume a hypocaloric diet and take either the same supplement used in the summarized study or a placebo. After 12 weeks of supplementation, taking WKBE reduced weight more than taking a placebo (−6.4 lbs vs. −2 lbs, −2.9 kg vs. −.9 kg).^[4] Furthermore, more participants in the WKBE group achieved clinically meaningful weight loss than the placebo group (31% vs. 8%). Additionally, during a 24-week weight-maintenance phase, 74% of participants in the WKBE group maintained their weight loss.

A meta-analysis of 11 randomized controlled trials (573 participants) published in 2018 also supports the findings of the summarized study.^[5] Most of these trials did not involve caloric restriction, and the most common dosage of WKBE was 3,000 mg per day, with 1,000 mg taken at each main meal. It was reported that supplementing with WKBE reduced weight by a little over 2.2 pounds (1 kg), compared to the control. Additionally, according to 3 randomized controlled trials, WKBE reduced fat mass.

Although the summarized study also reported a decrease in fat mass in the WKBE groups, there was a decrease in fat-free mass in the WKBE groups. This could be seen as a downside, but the intervention was not designed to preserve muscle mass.

A hypocaloric diet is known to decrease muscle mass. It’s estimated that in adults ages 19–50 with overweight and obesity who are not performing structured exercise, for every 10 lb of weight loss, there’s about a 1–1.5 lb loss of muscle mass in women and 2–2.5 lb loss of muscle mass in men.^[6]

This is why the suboptimal changes in body composition in the WKBE groups isn’t unexpected, because a structured exercise program was not part of the intervention. Also, the diets were not optimized to preserve muscle mass. The specific instructions were to consume “approximately 45–60% of energy from carbohydrates and 20–30% of energy from fat.” There was no mention of protein intake, which is of the utmost importance for preserving muscle mass.^[7]

Ultimately, the results of the summarzied study add to a convincing body of evidence indicating that supplementing with WKBE — whether it’s in the context of a hypocaloric diet or not — promotes weight loss to a small degree.

White kidney bean extract for weight loss Original paper