Effect of D-β-Hydroxybutyric Acid on Body Fat in Japanese Adults: A Randomized, Double-Blind, Placebo-Controlled Study

Ketone metabolism is currently being spotlighted for its health benefits. Strict dietary carbohydrate restriction is required to increase plasma ketone levels, which can be achieved with D-β-hydroxybutyric acid (D-BHB) supplementation as well. Although 2.9 g/day of D-BHB may reduce body fat without dieting or exercise interventions, the lower effective intake limit of exogenous D-BHB remains unknown. In this randomized, double-blind, placebo-controlled study (UMIN000054231), we aimed to assess the safety and fat-reduction effects of a 12-week intake of D-BHB in healthy Japanese adults (low-dose [1.5 g/day, n = 33], normal-dose [2.9 g/day, n = 33], and placebo [n = 34] groups). Blood samples were collected pre- and post-intervention. Participants’ blood chemistry, anthropometric, and body composition parameters were investigated. The low-dose group had a lower visceral fat area and body mass index (BMI) and higher plasma ketone levels than the placebo group. The normal-dose group had a significantly lower visceral fat area than the placebo group. Significant between-group (normal-dose vs. placebo) differences were observed in body weight, BMI, body fat percentage, fat mass, and plasma ketone levels. Participants reported no D-BHB-related adverse effects or discomfort. In conclusion, 1.5 or 2.9 g/day of D-BHB may reduce body fat without dieting or exercise interventions.