Does berberine help with weight loss?
Berberine leads to modest weight loss in some studies, but a large well-designed study found no effect on visceral fat. It is not a powerful slimming agent, but may offer additional benefits for people with elevated cholesterol or type 2 diabetes.
Berberine reduces body weight in meta-analyses, but the effect is small and outcomes vary. One meta-analysis of twelve randomised trials found a mean reduction of 2.07 kg, while another meta-analysis of ten trials found no significant weight loss. A more recent meta-analysis of 23 trials found a mean reduction of 0.88 kg. Anyone expecting a spectacular result will be disappointed.
On two other measures the picture is somewhat more consistent. Waist circumference decreased by an average of 1 to nearly 3 cm across multiple meta-analyses. BMI decreased by 0.29 to 0.48 kg/m². These are small, statistically significant effects, but not large changes.
A large double-blind study with 337 participants and a duration of six months is therefore sobering: in people with obesity and fatty liver disease, berberine (1 gram per day) produced no significant reduction in visceral fat or liver fat compared with placebo. That is one of the most relevant findings, precisely because this study was well designed and focused on the people who would typically be expected to benefit most. Berberine did, however, significantly lower LDL cholesterol and another blood lipid marker in that same study.
In people with obesity and type 2 diabetes, a combination of berberine with the herbal extract silymarin performed better in a one-year study of 136 participants: visceral fat, BMI, waist circumference and blood sugar all improved significantly. Whether berberine alone produces the same effect in this group remains unclear.
Berberine appears reasonably safe in the short term. In the large study, side effects were comparable to placebo. Gastrointestinal complaints are the most common, but they decreased within the first month. Effects with long-term use are less well studied.
Based on multiple meta-analyses of randomised trials and one large (337 participants) double-blind RCT. The studies are heterogeneous with respect to population, dose and duration, which partly explains the conflicting results.