The aim of the present study was to examine the effects of green tea epigallocatechin-3-gallate (EGCG) on changes in body composition, energy and substrate metabolism, cardiometabolic risk factors and liver function enzymes after an energy-restricted diet intervention in obese women. In the present randomised, double-blind, placebo-controlled study, eighty-three obese (30 kg/m2>BMI < 40 kg/m2) pre-menopausal women consumed 300 mg/d of EGCG or placebo (lactose). We measured body weight and adiposity (dual-energy X-ray absorptiometry), energy expenditure and fat oxidation rates (indirect calorimetry), blood lipid levels (TAG, total cholesterol, LDL-cholesterol and HDL-cholesterol), insulin resistance, C-reactive protein and liver function markers (aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, γ-glutamyltransferase, urea, bilirubin and 2-keto[1-13C]isocaproate oxidation) before and after the intervention in the EGCG and control groups. We did not find any significant difference in the changes in body weight ( − 0·3 kg, 95 % CI − 5·0, 4·3), fat mass ( − 0·7 kg, 95 % CI − 3·5, 2·1), energy (0·3 kJ/kg per d, 95 % CI − 3·1, 2·7) and fat ( − 0·1 g/min, 95 % CI − 0·03, 0·01) metabolism, homeostasis assessment model for insulin resistance (0·2, 95 % CI − 0·2, 0·7), total cholesterol ( − 0·21 mmol/l, 95 % CI − 0·55, 0·13), LDL-cholesterol ( − 0·15 mmol/l, 95 % CI − 0·50, 0·20), TAG ( − 0·14 mmol/l, 95 % CI − 0·56, 0·29) and liver function markers between the EGCG and control groups. In conclusion, the present results suggest that dietary supplementation with 300 mg/d of EGCG for 12 weeks did not enhance energy-restricted diet-induced adiposity reductions, and did not improve weight-loss-induced changes in cardiometabolic risk factors in obese Caucasian women. The intake of 300 mg/d of EGCG for 12 weeks did not cause any adverse effect on liver function biomarkers.