Are you hitting the treadmill but not dropping pounds? Beware: Too much cardio can spike muscle-eating stress hormones, like cortisol, and hinder thyroid hormones, leading to fatigue and slowed metabolic rate (the rate at which you burn calories at rest), says Natasha Turner, ND. Plus, long, moderate-intensity aerobic workouts tend to lower levels of the satiating hormone leptin, making you ravenous afterward, says Jade Teta, ND.

In contrast, both experts say, strength training along with short, intense cardio sessions stimulates fat-burning hormones like testosterone and human growth hormone, bolstering metabolism.

Try 30- to 45-minute workouts three times weekly, combining intervals (cardio bursts punctuated by brief rests) and strength training. On “off” days, walk for 30 to 60 minutes.