Mesomorphs tend to have a medium build with natural muscularity. They can gain body fat over time and with age. Mesomorphs typically sit somewhere between the other two body types in their propensity for weight gain. Mesomorphs often respond well to resistance training, but may benefit from additional aerobic activity as they age to maintain good body composition.
Though naturally muscular, consistency and nutritional balance are important to optimize either fat loss or weight gain. Mesomorphs can acclimate to both increased or decreased food intake, but they tend to adapt to decreased food intake faster as they get older.
Switching between strategic “up-adjusting” (increased fuel) and “down-adjusting” (decreased fuel) is usually effective for Mesomorphs trying to lose fat or stay lean while adding muscle.