Alternate day fasting is known to be helpful to control weight and have a positive effect on insulin resistance and cardiovascular risk factors. However, there have been no studies on weight reduction program combining alternate day fasting with exercise which preserves lean mass in Korea. The purpose of this randomized clinical trial is to examine the effects of alternate day fasting and exercise on weight reduction, visceral fat, and metabolic parameters in overweight or obese adults.

Inclusion Criteria:

• Age 20-65 years
• Body mass index (BMI) more than 23.0 kg/m² (overweight or obese for Asian populations, according to the World Health Organization)

Exclusion Criteria:

• Participants with weight gain more than 5kg in the last 3 months
• Participants with history of bariatric surgery
• Participants with secondary obesity, such as hypothyroidism
• Participants with uncontrolled hypertension or type 1 diabetes
• Participants who are taking anti-diabetic medications due to type 2 diabetes
• Participants with hepatic disease (AST or ALT ≥200 mg/dL)
• Participants with renal disease (serum creatinine ≥2.0 mg/dL)
• Participants with pancreatitis or related disorders
• Participants with acute infectious diseases (i.e., pneumonia, acute enteritis, or urinary infection)
• Participants with chronic inflammatory diseases (i.e., rheumatoid arthritis, or lupus)
• Participants with overeating behavior
• Participants with history of cardiovascular diseases
• Participants with history of cancer
• Participants who are taking anti-obesity, anti-diabetic, diuretic, central-nervous system, antidepressant, antipsychotic, or steroid medications
• Pregnant or lactating women
• Participants who intake more than 30 g of alcohol daily
• Night-time or shift-work workers
• Participants with chronic malabsorption syndrome or cholestasis
• Participants with other medical conditions that would preclude subjects from participating in exercise and physical test