How many calories should I eat to lose weight?

Start about 10 to 20 percent below your maintenance calories (your TDEE), which for many people means 300 to 500 fewer calories a day. Track your food and weekly average weight for two to four weeks, then adjust. Without medical supervision, health experts advise not going below about 1,200 calories a day for women or 1,500 for men.

1. Estimate your maintenance. Use a TDEE calculator for a starting number, then confirm it by eating that amount for two weeks while your weight holds steady.
2. Set a moderate deficit. Eat about 10 to 20 percent below maintenance. Bigger cuts are harder to keep up and cost more muscle.
3. Keep protein high. Aim for about 1.6 to 2.2 grams of protein per kilogram of body weight to protect muscle while you eat less.
4. Track and weigh in. Log what you eat, and weigh yourself a few mornings a week. Compare weekly averages, not single days.
5. Adjust every few weeks. If the weekly average hasn't moved in two to three weeks, lower calories by 100 to 200 a day, or add some activity.

Find your starting number

Use the TDEE calculator for an estimate of the calories you burn a day. Take 10 to 20 percent off for your starting target. For someone with a TDEE of 2,400, that’s about 1,920 to 2,160 calories.

Why “3,500 calories a pound” isn’t the whole story

The old rule says cutting 3,500 calories loses a pound of fat. It’s close for the first few weeks, but it overstates weight loss over months. As you get lighter, your body burns less, so the deficit shrinks. A 2011 analysis in The Lancet showed weight loss follows a curve rather than a straight line. Expect to adjust your calories as you go.

Make the deficit easier to keep

• Fill up on protein and vegetables first.
• Save some calories for foods you enjoy, so the plan lasts.
• Keep lifting. Strength training helps you hold onto muscle while you lose fat.
• Don’t chase the scale every day. Water weight swings by a few pounds.

When to get help

If you have a health condition, take medication that affects appetite or weight, or have a history of disordered eating, work with a doctor or registered dietitian. If counting starts to feel stressful or controlling, take a break from it.