The objective of the present investigation was to evaluate the possible role of serotonin in the anti-obesity action of Nutrigrow fat burner capsules. The total ash value of the capsule powder was 8.15 % with 2.65 % acid insoluble ash and 4.55 % water soluble ash. The water soluble and alcohol soluble extractives were 1.58 % and 1.54 % respectively. The results of preliminary qualitative phytochemical screening revealed that all the classes of phytochemicals (alkaloids, glycosides, saponins, tannins, phenolics, flavonoids, proteins & amino acids, sterols and triterpenoids) were present in NFB. The anti-obesity effect of the NFB weight loss capsules was assessed by observing the effect of the capsule content on the food intake habit of experimental mice. It is visible from the results that NFB was immediate in exhibiting anorexic effect (50.000 % inhibition in the first 30 min) while its anorexic potential started to lower by the 4th hour (26.011 %). Both NFB and fluoxetine were effective in reducing the food intake significantly.