[PROBLEMS] To provide a body weight gain inhibitor which is to be used for obtaining an effect of inhibiting a body weight gain while having ordinary eating habits, and to provide a food, a drink, a material and so on having an effect of inhibiting body weight gain. [MEANS FOR SOLVING PROBLEMS] A body weight gain inhibitor which contains, as the active ingredient, aroma component(s) comprising essential oil components obtained from green leaves. The aroma component(s) comprise one member or a combination of two or more members selected from among (3Z)-hexanol, (3Z)-hexenol, (3E)-hexenol, (3E)-hexenal, (2E)-hexenol, (2E)-hexenal, n-hexenolandn-hexanal. A food or drink for inhibiting body weight gain, a material for inhibiting body weight gain, wherein the above-described body weight gain inhibitor is carried on a material, and so on each containing from 0.003 to 1% by weight of the aroma component(s) as described above.
