Aim of the study is to investigate the impact of energy flux (achieved by changes in physical activity) under the conditions of energy balance, caloric restriction and overfeeding in healthy subjects.

A low energy flux is achieved by low energy expenditure, equivalent to low physical activity and with a corresponding low energy intake. A high energy flux is achieved by high energy expenditure, equivalent to high physical activity and with a corresponding high energy intake, respectively.

The protocol of this randomized, intra-individual nutrition intervention includes 12 one-day interventions with 3 different levels of energy flux and 4 different diet conditions.

Inclusion Criteria:

• 20-40 years of age
• healthy
• BMI between 18.5 and 31 kg/m2

Exclusion Criteria:

• smoking
• food allergies
• alternative nutrition habits like vegetarian / vegan
• chronic diseases
• regular medication intake
• claustrophobia
• weight loss > 5 kg in the last 3 years