How big should my calorie deficit be?

Start from your maintenance calories

A deficit only means something relative to what you burn. Your maintenance number (TDEE) is your resting burn plus daily movement and exercise. If you eat 2,000 calories and burn 2,500, your deficit is 500.

Calculators give a starting estimate. Your real maintenance shows up after two or three weeks of logging food and weighing yourself. If your weekly average weight holds still, that intake is your maintenance.

Three deficit sizes and who they suit

Percentages scale better than fixed numbers, because 500 calories is a lot more for a 55 kg woman than for a 110 kg man.

• Mild, 10 to 15% (about 200 to 300 kcal): close to your goal weight, training hard, or you want it to feel almost effortless.
• Moderate, 15 to 25% (about 300 to 600 kcal): the default for most people. Steady loss, manageable hunger.
• Aggressive, 25% or more (600+ kcal): only if you have a lot of fat to lose and keep protein high. Expect more hunger and lower training performance.

How fast should the scale move?

A practical target is 0.5 to 1% of body weight per week. Research on lean athletes found that the slower rate (around 0.7% a week) kept more muscle and strength than a faster one.

The old rule that 3,500 calories equals one pound of fat overestimates loss over time, because your body adapts as you get lighter. Expect the rate to slow a bit after the first months and recheck your numbers every 4 to 6 weeks.

Floors you should not go below

Common guidance is not to drop below about 1,200 kcal a day for women and 1,500 kcal for men without medical supervision. Below that it gets hard to cover protein, vitamins and minerals.

Very low calorie diets (800 kcal or less) exist, but they are a medical treatment and should be run with a doctor.

Make the deficit easier to hold

The best deficit is the one you can keep for months. A few things help more than shaving off another 200 calories:

• Eat about 1.6 g of protein per kg of body weight to protect muscle and stay full.
• Keep lifting. Resistance training tells your body the muscle is still needed.
• Walk more. Steps add burn without making you as hungry as hard cardio.
• Judge progress by the weekly average weight, not single weigh-ins. Water and salt move the scale by a kilo or more day to day.