Role of Leucine on Muscle Preservation During Weight Loss in Older Men

Role of Leucine on Muscle Preservation During Weight Loss in Older Men

Overweight and obesity are part of a global health epidemic. However, older adults trying to lose weight face a dual challenge: first, muscle mass and strength naturally decline at an accelerating rate with age; second, effective weight loss diets like alternate-day fasting (ADF) are typically accompanied by significant muscle loss. Together, these factors can increase the risk of developing sarcopenia, a muscle disease characterized by critical losses in muscle mass and strength, especially when overweight or obese older adults try to lose weight through dieting alone. While high protein diets have often been advocated as a muscle preserving strategy when losing weight, recently, high leucine intake has been promoted for its critical role in stimulating muscle protein synthesis (MPS) with lower overall protein consumption, potentially reducing calorie intake while maintaining muscle during weight loss. Nonetheless, the effects of body mass-scaled protein and leucine intakes on muscular outcomes during weight loss remain uncertain. This study examines the effects of body mass-scaled protein and leucine supplementation on body composition during four weeks of ADF in older men.

Inclusion Criteria (all of the criteria):

• Of Asian descent
• Do not smoke or use tobacco products (including shisha)
• Have a body mass index (BMI = body mass in kilograms divided by the square of height in metres) ≥ 23 kg/m2

Exclusion Criteria (any of the criteria):

• Unable to adhere to the requirements regarding physical activity and diet as stated in the research methodologies. All supplements; including but not limited to vitamins, minerals, amino acids and proteins; which are not provided by this research, and traditional Chinese medicine are not allowed.
• Vegetarians or vegans due to potential differences in responses and that the supplements provided may contain dairy products.
• Allergic or intolerant to milk. The supplement that you will be required to consume may contain milk proteins, and lactose (milk sugar).
• Failed an exercise stress test.
• Have any health condition(s) that would be made worse by fasting.
• History of familial leucine-sensitive hypoglycaemia, i.e., highly symptomatic hypoglycaemia triggered by protein meals or the amino acid, leucine.
• Have diabetes, pre-diabetes, or abnormally high fasting blood glucose (> 6.0 mmol/L).
• Have uncontrolled hypertension (≥ 150/90 mmHg for ≥ 80 years old, ≥ 140/90 mmHg for < 80 years old).
• Have liver or kidney conditions.
• Have existing musculoskeletal conditions that could be exacerbated by the physical assessments in this study.
• More than twice per week of regular and structured resistance training (lifting weights).
• Competed in resistance exercise-related competitions in the past 6 months.
• Taking long-term prescribed medications (including traditional Chinese medicine and other alternative medicine), drugs, steroids, or hormones that can affect any of the measurements in this study.
• Have electrical implant (such as pacemaker, implantable cardioverter defibrillator or neurostimulator), metal or plastic implant/rod/plate, or joint replacement in the body as these objects can affect the accuracy of the body composition measurement.