Over 20? You Need To Read This Now! Teri Lynn Haass Fitness, Health September 11, 2014November 23, 2014lean, metabolism, muscle loss, strong 3 Comments Pop quiz: At what age do we start to lose muscle? a) 20s b) 30s c) 40s d) Over 50 Answer: a) Studies show that inactivity can cause muscle loss beginning in our late 20s…..Ouch. read more