Effects of licorice extract in combination with a low-calorie diet on obesity indices, glycemic indices, and lipid profiles in overweight/obese women with polycystic ovary syndrome (PCOS): a randomized, double-blind, placebo-controlled trial.

The short version

This 8-week randomized, double-blind, placebo-controlled trial with 66 women explored whether licorice (Glycyrrhiza glabra) root extract could ease some of the metabolic burden of polycystic ovary syndrome (PCOS), a hormonal condition marked by irregular ovulation, elevated androgen levels, and polycystic ovaries on ultrasound. PCOS frequently occurs alongside obesity and insulin resistance, the body's reduced response to insulin, which raises blood sugar and makes weight loss harder to achieve. The trial paired licorice extract with a calorie-restricted diet to test whether the herb added benefit beyond diet alone. Seventy-two overweight or obese women with PCOS, ages 18 to 45, at a clinic in Yazd, Iran, were randomly assigned to 1,500 mg of standardized licorice extract daily, taken as three capsules before meals, or a matching placebo, both alongside the same reduced-calorie diet, for 8 weeks. Sixty-six women completed the study. Body composition was measured with a bioelectrical impedance analyzer, and blood tests tracked fasting glucose, insulin, and cholesterol levels before and after treatment. Women taking licorice lost more weight than those on diet alone (82.60 kg versus 86.09 kg, a statistically significant difference at p<0.001) and showed larger drops in body mass index and body fat percentage. Their fasting blood sugar (74.0 versus 94.0 mg/dl), insulin (6.68 versus 11.06 µIU/ml), and an insulin-resistance score called HOMA-IR (1.23 versus 2.55) all improved significantly more than in the placebo group (p<0.001), as did triglycerides and total and LDL cholesterol (all lower with licorice) and HDL cholesterol (higher, the more favorable direction) (p between <0.001 and 0.01). A separate measure of insulin-producing capacity, HOMA-B, improved within the licorice group and looked better than placebo before statistical adjustment, but that edge disappeared once the analysis accounted for baseline differences and other factors, a reminder that not every raw difference holds up under closer scrutiny. Diet and activity levels were identical between the two groups throughout the study, and the low-calorie diet alone produced no measurable change in any of these markers over the 8 weeks. The authors propose that licorice's compounds act on fat metabolism, insulin signaling, and cholesterol handling through several biological pathways, though those pathways were not directly measured in this trial. The study ran for only 8 weeks, did not test licorice without the accompanying diet, and relied on 24-hour dietary recall, a self-reported method that can be imprecise. Longer trials isolating licorice's own effect and testing its proposed mechanisms, in more diverse populations than this single-center Iranian cohort, are needed to confirm these results.

Key findings

• In this 8-week clinical trial, women with polycystic ovary syndrome (PCOS, a hormonal condition involving irregular ovulation and elevated androgens) who took licorice (Glycyrrhiza glabra) root extract alongside a low-calorie diet lost significantly more weight than those who followed the same diet with a placebo.
• The licorice group also showed larger improvements in fasting blood sugar, insulin levels, and HOMA-IR (a calculation that estimates insulin resistance, meaning how well the body responds to insulin) compared with diet alone.
• Cholesterol markers moved in favorable directions with licorice: triglycerides, total cholesterol, and LDL ('bad') cholesterol decreased, while HDL ('good') cholesterol increased, more than with diet alone.
• A measure of insulin-producing capacity called HOMA-B improved with licorice before statistical adjustment, but the advantage over placebo did not hold up once other factors were accounted for, showing why not every early result survives closer analysis.
• The trial lasted only 8 weeks and did not test licorice without the accompanying diet, so it does not show whether licorice alone, or its benefits over a longer period, would produce the same results.

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