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What happens to your body when you're 30?: A Guide to Navigating Changes

By age 30, the average adult starts to lose 3% to 5% of muscle mass each decade, a process known as sarcopenia. This gradual, decade-long shift in muscle mass is just one of many changes that occur, prompting many to wonder, what happens to your body when you're 30? While you may not notice drastic differences overnight, your 30s are a critical time to establish healthy habits that will benefit your long-term health.