Total Daily Energy Expenditure adds your everyday movement and exercise on top of your resting burn. It's the single most useful number for weight management, since eating close to your TDEE keeps your weight roughly stable, while eating above or below it drives gain or loss.
This is the number to calculate before starting almost any diet or training plan, whether the goal is losing, gaining, or simply holding steady. Recalculate it whenever your activity level changes meaningfully — starting a new training block, recovering from injury, switching to a desk job, or taking on physical work — since your maintenance calories shift with it.
TDEE multiplies your BMR by an activity multiplier: 1.2 for a sedentary lifestyle, 1.375 for light activity, 1.55 for moderate activity, 1.725 for a very active routine, and 1.9 for extremely active people such as those with physical jobs or two daily training sessions. It's an estimate, so real-world results can vary by a few hundred calories.
Health Calc