Background Obesity and overweight may soon affect more than half of the population in some regions of the world and are associated with diabetes, hypertension and other diseases that cause morbidity, mortality and high health-care expenditure. No one approach, whether dietetic management, medication, or commercial weight loss programme, can alone solve the problem-all potential treatments need to be investigated and exploited. Among the herbal preparations known to non-western cultures are materials which may have applications in modulating physiological processes which influence gut motility, food intake and energy balance. One such mixed herbal preparation is 'YGD' containing Yerbe Mate (leaves of Ilex paraguayensis), Guarana (seeds of Paullinia cupana) and Damiana (leaves of Turnera diffusa var, aphrodisiaca). Aims This study had two distinct aims: to determine the effect of a herbal preparation 'YGD' containing Yerbe Mate, Guarana and Damiana on gastric emptying; to determine the effect of the same preparation on weight loss over 10 days and 45 days and weight maintenance over 12 months. Methods Gastric emptying was observed using ultrasound scanning in seven healthy volunteers following YGD and placebo capsules taken with 420 mL apple juice. Body weight was observed before and after 10 days of treatment with three YGD capsules or three placebo capsules before each meal for 10 days in 44 healthy overweight patients attending a primary health care centre. Forty-seven healthy overweight patients entered a double-blind placebo-controlled parallel trial of three capsules of YGD capsules before each main meal for 45 days compared with three placebo capsules on body weight. Body weight was monitored in 22 patients who continued active (YGD capsules) treatment for 12 months. Results The herb preparation YGD was followed by a prolonged gastric emptying time of 58 +/- 15 min compared to 38 +/- 7.6 min after placebo (P = 0.025). Body weight reductions were 0.8 +/- 0.05 kg after YGD capsules compared to 0.3 +/- 0.03 kg after placebo capsules over 10 days, and 5.1 +/- 0.5 kg after PGD capsules compared to 0.3 +/- 0.08 kg after placebo over 45 days. Active treatment with YGD capsules resulted in weight maintenance of the group (73 kg at the beginning and 72.5 kg at the end of 12 months). Conclusions The herbal preparation, YGD capsules, significantly delayed gastric emptying, reduced the time to perceived gastric fullness and induced significant weight loss over 45 days in overweight patients treated in a primary health care context. Maintenance treatment given in an uncontrolled context resulted in no further weight loss, nor weight regain in the group as a whole. The herbal preparation is thus shown to be one that significantly modulates gastric emptying. Further clinical studies with dietetic monitoring of energy intake, dietary quality, satiety ratings, body weight and body composition are now indicated, and examination of the active principles contained in the three herbal components may prove rewarding.
