In animal studies, food deprivation increases drub self-administration, but this phenomenon has never been systematically and experimentally studied in humans. This single-blind, cross-over, residential study addresses this issue by evaluating the effect on cigarette smoking and craving for cigarettes in 15 nicotine-dependent, normal weight subjects of four different diets fed to each subject for six days apiece: (1) normal; (2) normal with high carbohydrates; (3) calorie restricted, low carbohydrate (ketotic); and (4) calorie restricted, high carbohydrate. Dependent variables include cigarette use (by self-report and expired breath CO), subjective craving for cigarettes, hunger, mood, and resting metabolic rate. Data collection is continuing, with 5 subjects having completed the study.