Disclosed are a composition for anti-obesity comprising a pulverized material of Odontella aurita as an active ingredient and a method of processing Odontella aurita to improve the anti-obesity effects. The pulverized material may be a microfluidizer-processed pulverized material of Odontella aurita. The pulverized material exhibits the effect of inhibiting weight gain and the effect of inhibiting body fat accumulation in mice fed with a high-fat diet.