We hypothesised that GT ingestion during a LED might compensate for the reduction in REE and prevent weight regain and thus weight-cycling (the yo-yo effect). Because of possible interactions between GT and habitual caffeine intake level, we investigated the effect of GT in the context of a controlled but realistic caffeine level (Kovacs et al. 2004). The aim of the pre- sent study was therefore to investigate whether GT ingestion, independent of habitual caffeine intake, increased REE and sub- strate oxidation, whether this effect was present after a 4-week administration of GT along with a LED (meal replacement diet plan) and whether GT ingestion during the LED offset the expected reduction in REE. Furthermore, we investigated the effect of a 12-week GT administration during the LED on body weight and fat loss. We hypothesised that GT might increase REE and fat oxidation compared with PLAC, and that this effect might be present after a 4-week ingestion of GT along with a LED (meal replacement diet plan). We further hypoth- esised that GT might offset the reduction in REE that is expected to occur during the LED and that GT might stimulate the loss of body weight and fat.