Muscle-to-Fat Ratio Key for Brain Health
A new study reveals that muscle-to-fat ratio—not just weight or BMI—is the key number for brain health. Building or maintaining lean muscle mass may offer significant cognitive benefits, underscoring the value of strength training for everyone.
- A study presented at the Radiological Society of North America (RSNA) analyzed 1,164 healthy adults with an average age of about 55. It used whole-body MRI scans and an AI algorithm to measure muscle volume, visceral fat (fat surrounding internal organs), subcutaneous fat (fat under the skin), and to estimate the biological age of the brain. - The research found that a higher ratio of visceral fat to muscle was linked to an older-appearing brain, while subcutaneous fat had no significant association with brain age. This highlights that the "hidden" fat deep in the abdomen is a greater concern for brain health than the fat just under the skin. - Sarcopenic obesity, the combination of low muscle mass and high-fat mass, has been associated with poorer performance on cognitive tests, particularly in executive function and orientation. A meta-analysis of eight studies involving 87,520 participants found a significant link between sarcopenic obesity and cognitive dysfunction. - The connection between muscle and brain health may be explained by myokines, which are proteins released by muscle fibers during contraction. These myokines can enter the bloodstream and are thought to control brain functions like learning, memory, and mood, potentially mediating the cognitive benefits of exercise. - One specific myokine, Brain-Derived Neurotrophic Factor (BDNF), is released by skeletal muscle and is essential for the growth, survival, and communication of brain cells. Both aerobic and resistance training have been shown to increase BDNF levels. - Another way muscle may influence brain health is by reducing inflammation. Interleukin-6 (IL-6), a myokine released during exercise, has anti-inflammatory effects that can counter chronic systemic inflammation, a known risk factor for cognitive decline. - Research also suggests that nerves play a role in this communication. When the brain signals nerves to move a muscle, the nerves not only instruct the muscle to contract but also prompt it to release more of these brain-boosting molecules. - This area of research may lead to new interventions for preserving cognitive function, including therapies that aim to selectively reduce visceral fat while maintaining muscle mass. This is particularly relevant with the rise of weight-loss medications that can cause both fat and muscle loss.
