Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients: a placebo-controlled, double-blind 8-week intervention in obese subjects

Background: A combination of tyrosine, capsaicin, catechines and caffeine may stimulate the sympathetic nervous system and promote satiety, lipolysis and thermogenesis. In addition, dietary calcium may increase fecal fat excretion. Objective: To investigate the acute and subchronic effect of a supplement containing the above mentioned agents or placebo taken t.i.d on thermogenesis, body fat loss and fecal fat excretion. Design: In total, 80 overweight-obese subjects ((body mass index) 31.2 +/- 2.5 kg/m(2), mean +/- s.d.) underwent an initial 4-week hypocaloric diet (3.4 MJ/day). Those who lost > 4% body weight were instructed to consume a hypocaloric diet (-1.3 MJ/day) and were randomized to receive either placebo (n = 23) or bioactive supplement (n = 57) in a double-blind, 8-week intervention. The thermogenic effect of the compound was tested at the first and last day of intervention, and blood pressure, heart rate, body weight and composition were assessed. Results: Weight loss during the induction phase was 6.8 +/- 1.9 kg. At the first exposure the thermogenic effect of the bioactive supplement exceeded that of placebo by 87.3 kJ/4 h (95%CI: 50.9; 123.7, P = 0.005) and after 8 weeks this effect was sustained (85.5 kJ/4 h (47.6; 123.4), P = 0.03). Body fat mass decreased more in the supplement group by 0.9 kg (0.5; 1.3) compared with placebo (P < 0.05). The bioactive supplement had no effect on fecal fat excretion, blood pressure or heart rate. Conclusion: The bioactive supplement increased 4-h thermogenesis by 90 kJ more than placebo, and the effect was maintained after 8 weeks and accompanied by a slight reduction in fat mass. These bioactive components may support weight maintenance after a hypocaloric diet.