Subjects in this group are metabolically normal. They have low liver fat defined as less than five percent as determined by magnetic resonance spectroscopy.

Intervention: Subjects will begin an 8-12 week high-calorie diet intervention. They will eat an additional 1000 kcal/day for two to three months, until a moderate, approximately 5% weight gain is achieved. The recommended dietary energy intake will be 1000 kcal/d more than the subject's baseline resting energy expenditure. An individualized diet plan will be developed for each subject by the study dietitian based on estimated energy requirements, and the subject's food preferences and dietary habits.

Subjects in this group are metabolically abnormal. They have high liver fat defined as at least ten percent as determined by magnetic resonance spectroscopy.

Intervention: Subjects will begin an 8-12 week high-calorie diet intervention. They will eat an additional 1000 kcal/day for two to three months, until a moderate, approximately 5% weight gain is achieved. The recommended dietary energy intake will be 1000 kcal/d more than the subject's baseline resting energy expenditure. An individualized diet plan will be developed for each subject by the study dietitian based on estimated energy requirements, and the subject's food preferences and dietary habits.

Subjects will begin an 8-12 week high-calorie diet intervention. They will eat an additional 1000 kcal/day for two to three months, until a moderate, approximately 5% weight gain is achieved. The recommended dietary energy intake will be 1000 kcal/d more than the subject's baseline resting energy expenditure. An individualized diet plan will be developed for each subject by the study dietitian based on estimated energy requirements, and the subject's food preferences and dietary habits.