In this episode of Longevity Roadmap, Dr. Keith Baar, professor of physiology at UC Davis, dives into the molecular science of muscle growth, metabolism, and ageing. Host Buck Joffrey explores how diet, exercise, and cellular signalling pathways like mTOR interact to influence healthspan and longevity—and whether more muscle is always better.

Key Points:

This episode clarifies the complex role of mTOR in muscle growth and ageing, showing that building strength can boost longevity when done right. With smart training and nutrition, it’s possible to age with vitality—without compromising health.

• mTOR- The Anabolic-Longevity Balancing Act: The mTOR pathway helps muscles grow but is also linked to ageing and cancer risk. Dr. Baar explains how exercise activates mTOR in specific muscles without triggering harmful systemic effects—unlike drugs like rapamycin, which blunt mTOR across the body.
• Muscle Mass Supports Longevity: Contrary to myths, muscle isn’t harmful to lifespan. In fact, midlife strength is one of the strongest predictors of reaching 100. Bodybuilders may face health risks, but it's due to anabolic drug use, not muscle mass itself.
• How Diet Shapes Muscle and Ageing: A ketogenic diet lowers insulin and global mTOR activity, mimicking some anti-ageing effects. When paired with resistance training, it still allows local mTOR activation for muscle growth—while preserving mitochondria-rich muscle fibres in older adults.
• Exercise Type Matters-Resistance vs. Endurance: Resistance training boosts muscle size and strength via mTOR activation, while endurance training promotes mitochondrial renewal and metabolic health by temporarily suppressing mTOR—offering complementary longevity benefits.
• Practical Workout Advice: To build muscle, lift any weight to failure—low or heavy, as long as you reach fatigue. One hard set per muscle group, twice weekly, is enough for most people. Dr. Baar also recommends adding simple isometric “exercise snacks” throughout the week to maintain muscle in older age.