Don't trust fitness tracker calorie counts

What to Do

Treat calorie burn numbers from your watch or app as rough estimates, not facts. A Stanford analysis of 7 fitness devices found they overestimate calorie burn by 27-93%. A simpler rule of thumb: running burns approximately 80-100 calories per mile.

Why It Works

The Apple Watch has a ~28% mean error across activities (2025 meta-analysis of 56 studies). Humans overestimate exercise calories by ~36% on average, and overweight individuals overestimate by up to 72%. This creates a dangerous feedback loop: overestimate burn, eat more to "compensate," and wonder why weight isn't changing.

Tips

• Running 3 miles 3x/week burns roughly 750-900 extra calories — about 1 pound per month without dietary changes
• "Compensatory eating" (eating more because you exercised) is the primary reason running alone often fails for weight loss
• Running paired with modest caloric restriction is far more effective than either alone
• Focus on how running makes you feel rather than the calorie number on your watch