This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Animal data suggest that olanzapine induces weight gain by alterations in leptin levels. The goal of this study is to determine if the acute effects of olanzapine is to attenuate plasma leptin and alter glucose tolerance in human subjects. This study will enroll approximately 32 healthy volunteers ages 18-30, with BMI 20-25 without psychiatric disorders or chronic disease to receive 3 days of treatment with 10 mg olanzapine or placebo, then crossed over after one week to receive the opposite treatment. Subjects will take one pill daily for the 3 days up to the GCRC visit. During this time they will follow a 3 day 300g carbohydrate diet. Subjects will complete surveys of their hunger, have blood tests for free fatty acids, glucose, insulin and leptin and then undergo the oral glucose tolerance test. These same procedures will be repeated 1-2 weeks later.