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 Maté (leaves of Ilex paraguayensis), Guarana (seeds of Paullinia cupana) and Damiana (leaves of Turnera diffusa var. aphrodisiaca).