Women aged 17–35 who use diet and fitness apps that track calorie intake or both diet and exercise exhibit significantly higher levels of disordered eating behaviors, body dissatisfaction, and compulsive exercise than those who use fitness-only apps or no apps.

When a person repeatedly tracks every calorie they eat or every step they take, their brain starts linking food and movement with strict rules and self-judgment. This constant monitoring activates stress systems and reduces the brain’s natural reward response to eating or exercise. Over time, the body learns to associate normal eating or rest with failure, which increases anxiety and the drive to control behavior through more tracking or exercise.