How Much of a Calorie Deficit to Lose Weight?

Most adults do well with 275 to 550 kcal a day, though the right gap depends on your size. By the old rule that is 0.25 to 0.5 kg (0.55 to 1.1 lb) a week. The NHS gives 0.5 to 1 kg as its range. I stop at 1% of body weight a week, and your intake never goes under the floor.

How much of a calorie deficit to lose weight is enough?

The smallest calorie deficit you will actually hold. The AHA, ACC and TOS guideline says adults in structured lifestyle programs are typically prescribed a deficit of at least 500 kcal a day. It names 500 or 750 kcal as options. That is about 0.45 to 0.68 kg a week on paper. A smaller gap still counts. A 275 kcal gap, held for four weeks, adds up to 7,700 kcal, which is about 1 kg by the 7,700 kcal per kg rule.

I put 275 in the range even though the guideline starts at 500, because the guideline describes structured programs and you are probably on your own. A gap that holds is worth more than a bigger one that breaks by Thursday.

Step for today: write down your maintenance, then subtract 275 and 550. You now have the two ends of the range to test.

What is a safe daily calorie deficit for weight loss?

One that clears three limits at once. I check them in this order.

1. The pace. The NHS aims for 1 to 2 lb (0.5 to 1 kg) a week, and the CDC calls about 1 to 2 pounds a week gradual and steady.
2. Your body weight. A review by Helms and colleagues for lifters in contest prep sets intake to lose about 0.5 to 1% of body weight a week. At 70 kg (154 lb), 1% is 0.7 kg, or 770 kcal a day.
3. The floor. The guideline’s prescribed ranges start at 1,200 kcal for women and 1,500 kcal for men. Diets under 800 kcal belong in medical care.

The pace limit is the loosest of the three. The weight limit and the floor are the ones that bite. The table shows what each gap leaves on the plate for three people who maintain at 2,000, 2,400 and 2,800 kcal. I added the share of maintenance each gap removes.

Maintenance	275 kcal gap	550 kcal gap	825 kcal gap
2,000 kcal	1,725 kcal (14% cut)	1,450 kcal (28% cut)	1,175 kcal (41% cut), below both floors
2,400 kcal	2,125 kcal (11% cut)	1,850 kcal (23% cut)	1,575 kcal (34% cut)
2,800 kcal	2,525 kcal (10% cut)	2,250 kcal (20% cut)	1,975 kcal (29% cut)

A small eater feels the same gap as a bigger cut. A 550 kcal gap removes 28% of a 2,000 kcal day and 20% of a 2,800 kcal day. At 2,000 kcal of maintenance, an 825 kcal gap lands under both floors. That pace is off the table.

Your own row is missing from that table, so run your age, height, weight and activity through the calorie calculator, which applies the NASEM 2023 equations. It keeps every target at or above 1,200 kcal for women and 1,500 kcal for men.

Why not take the biggest deficit I can?

A bigger gap takes more lean mass along with the fat. According to Helms and colleagues, lean mass makes up a larger share of the weight lost the deeper the deficit goes. They cite a study of athletes who lost 1.4% of body weight a week against 0.7% a week, over four to eleven weeks. Fat mass fell 21% in the faster group and 31% in the slower group. Lean mass rose 2.1% in the slower group and stayed flat in the faster one. In strength-training women, losing 1 kg a week rather than 0.5 kg for four weeks came with a 5% decrease in bench press strength, in their account. These were athletes and lifters, so I read the results as a direction and not a prediction for you. Protein is the lever on the food side, and how much protein to eat to lose weight has its own numbers.

Regain points the other way. In it by Purcell and colleagues, adults with a BMI of 30 to 45 followed a 12-week rapid or a 36-week gradual program. After 144 more weeks, the completers had regained 70.5% of the lost weight in the rapid group and 71.2% in the gradual group. Over those 144 weeks, rapid loss wasn’t regained faster. In the rapid group, 81% reached the 12.5% loss in time, against 50% in the gradual group.

The regain data don’t back a rule against fast loss, so my case for a moderate gap rests on the lean mass Helms describes and the margin for error in your maintenance estimate. The gap itself isn’t optional, as losing weight without a calorie deficit explains.

How do I choose between 275, 550 and 825?

When unsure, take the smaller number. The NASEM equations have a typical error of 246 kcal a day for women and 339 kcal for men, so a planned 275 kcal gap is about the size of that error. Two weeks of weigh-ins tell you more than the first estimate, so compare weekly averages and not single mornings. If you count macros for weight loss, set the gap first and split it into protein, fat and carbs after.

My own checks, in order:

• Multiply your weight in kg by 11 to get the 1% limit in kcal. Under 50 kg that is below 550, so stay at 275. At 55 kg the limit is 605 kcal, so 550 is the ceiling.
• If maintenance minus 550 lands within 250 kcal of your floor, use 275. A small error in your maintenance could push you under.
• If you maintain at 2,400 kcal or more, 550 is a comfortable middle.
• If you’re unsure of your maintenance, use 275 for the first two weeks and let the weigh-ins show where you really are.

A large maintenance changes the answer. Take a man aged 38, 178 cm and 100 kg who is low active. The equation gives 3,141 kcal. For him 1% of body weight is 1 kg a week, or 1,100 kcal a day. An 825 kcal gap is allowed and is a 26% cut. The same pace is out of reach for the 2,000 kcal woman in the table.

What does a 275 kcal gap look like in food?

It is small, which is the point. I took six records from USDA FoodData Central and worked out how much of each carries 275 kcal. Each energy figure uses the record’s own Atwater factors when it lists them.

Food (state)	Grams for 275 kcal	In portions
Rice, white, medium-grain, cooked	211 g	1.1 cups (186 g each)
Bread, white	102 g	3.7 slices (27.3 g each)
Cheddar cheese	67 g	4 slices (17 g each)
Croissant, butter	68 g	1.2 medium (57 g each)
Beer, regular	640 g	1.8 cans (356 g each)
Peanut butter, creamy	47 g	no portion in the record

One or two of these swaps cover the gap. Half a croissant plus one beer comes to about 270 kcal. Trimming the peanut butter on your toast by 25 g saves 147 kcal at 589 kcal per 100 g. Pick the one or two items you eat most often, weigh them for a week, and see which cut you would not miss.

How should I change my deficit as I lose weight?

Recalculate every few kilograms, because a lighter body uses less energy. In the NASEM equations, each kilogram you lose cuts maintenance by 11.71 kcal for an inactive woman and 14.10 kcal for an inactive man. For low active adults it is 12.14 and 14.94 kcal. Lose 10 kg and your maintenance falls by 117 to 149 kcal a day, if age and height stay the same.

If you keep eating the same food, a 550 kcal gap shrinks to about 400 to 430 kcal. You have two options. Accept a slower pace, or lower your target by about 120 to 150 kcal. Both are fine. Keeping the old number while the scale slows is the option that fails. Hall and colleagues describe the same slowing in their model, where weight change has a half-time of about one year.

I also plan a short stretch at maintenance every so often, so the averages can catch up and I can see where maintenance really sits. That’s a habit of mine, not a published protocol.

My numbers are for adults with a real reason to lose weight. Pregnancy, breastfeeding, a medication or a health condition puts the plan in your doctor’s hands, and a past eating disorder means seeing a professional first.

If counting calories has started to feel hard to stop, or eating feels out of control, talk to someone: ANAD in the US (1-888-375-7767), Beat in England (0808 801 0677), NEDIC in Canada (1-866-633-4220) or the Butterfly Foundation in Australia (1800 33 4673). If you’re in danger right now, call your local emergency number. Other UK numbers and crisis lines are on our crisis support page.