The Effects of a 4-week Supplementation With a Ketogenic Nutrient Mix on 24-hour Substrate Metabolism and Muscle Health

Inclusion Criteria: * Aged 60-80 years * Body mass index (BMI) 25-35 kg/m2 * Sedentary lifestyle (not more than 2 hours of structured physical activity per week in the past 3 months) * Stable dietary habits (no weight loss or gain \> 5 kg in the past 3 months) * Healthy (as determined by dependent physician based on medical questionnaire) * Regular sleeping habits (7-9h of daily sleep) Exclusion Criteria: * Type 2 diabetes * Participants with active congestive heart failure and/or severe renal and or liver insufficiency * Uncontrolled hypertension * Alcohol consumption of \>3 servings per day for men and \>2 servings per day for women * Unstable body weight (weight gain or loss \> 5 kg in the last 3 months) or intention to lose weight * Participants who are on an intermittent fasting diet * Previous enrolment in a clinical study with an investigational product during the last 3 months or as judged by the investigator which would possibly hamper our study results * Significant food allergies/intolerance (seriously hampering study meals or study product) * Participants who do not want to be informed about unexpected medical findings * Blood donation during or within 2 months prior to the study * Disturbances in circadian rhythm determined with the follow criteria: * Extreme early bird or extreme night person (score ≤30 or ≥70 on MEQ-SA questionnaire) * Heavily varying sleep-wake rhythm * Night shift work during last 3 months * Travel across \> 1 time zone in the last 3 months * High daily caffeine intake \> 400mg (more than 4 cups of coffee or energy drinks)