Using TDEE to Lose or Gain Weight

Your TDEE is your maintenance number — roughly what you burn, and therefore roughly what you'd eat to stay where you are. Turning it into a weight-loss or weight-gain target is simple arithmetic, but the size of the step you choose matters more than the arithmetic does.

The basic idea

Eat below your TDEE over time and you tend to lose weight; eat above it and you tend to gain. A gap of about 500 kcal per day corresponds to roughly 0.5 kg per week, which is the pace most guidance treats as sustainable.

Our TDEE Calculator shows these targets alongside your maintenance figure:

Using the worked example from how to calculate your TDEE — a maintenance figure of 1,917 kcal — a weight-loss target would be about 1,417 kcal/day, and a gain target about 2,417 kcal/day.

Why bigger deficits usually aren't better

A larger daily gap looks like faster progress, and for a while it can be. The catch is that very aggressive deficits are harder to sustain, and an approach you abandon in three weeks loses to a gentler one you keep for six months. Steeper deficits also tend to cost more lean mass alongside fat, and make training noticeably harder to recover from.

The gradual options above exist for this reason. A 250 kcal step is easier to hold, easier to combine with training, and far less likely to end in the all-or-nothing cycle that a severe deficit invites.

Your starting number is a hypothesis

Remember where the target comes from: an estimated BMR multiplied by an activity level you selected. Both carry uncertainty, and individual metabolism varies by roughly ±10–15% regardless. Your first target is a well-informed starting point, not a prescription.

So test it the same way you'd test any estimate:

1. Hold the target for two to three weeks.
2. Track a weekly average weight, not daily readings — day-to-day swings are mostly water, food volume, and timing.
3. If nothing is moving, adjust by a modest step (100–200 kcal) rather than slashing further, and check your activity level first — see choosing your activity level honestly, which is the most common source of a wrong starting number.

As you lose or gain weight, your TDEE moves too — a smaller body burns less. It's worth recalculating every few kilograms rather than holding the original figure indefinitely.

Calories aren't the whole picture

The total sets the direction; what makes up that total affects how the process feels and what you keep.

• Protein helps preserve lean mass in a deficit and is the most satiating macronutrient. The Protein Intake Calculator sets a target for your body weight and training.
• Macro balance — the Macro Split Calculator takes your TDEE and divides it into protein, carbohydrate, and fat.
• Resistance training is what signals your body to hold onto muscle while losing fat. Calories decide the direction; training influences the composition of the change.
• Weight is not the only measure. The Body Fat Calculator and Waist-to-Height Ratio Calculator capture changes the scale alone can hide, especially early on when body composition shifts before weight does.

The bottom line

Take your TDEE, subtract about 500 for loss or add about 500 for gain, and treat the result as a starting hypothesis to test over two to three weeks. Choose a gentler step if the larger one isn't something you can sustain — consistency beats severity. Recalculate as your weight changes, and bring anything that matters to a qualified professional.

Get your maintenance figure and goal targets on the TDEE Calculator.