There’s a number floating around every diet forum: eat 1,200 calories and the weight comes off. It’s wrong for almost everyone who repeats it, because a calorie target that isn’t built from your own maintenance level is just a guess wearing a lab coat. Working out how many calories you should eat to lose weight takes two steps, and the second one is where most plans quietly fall apart. Get your maintenance figure from the CalcRange Calorie Calculator first, then use this to set the deficit properly.
Key Takeaways
- Your weight loss calorie target is your maintenance level (TDEE) minus a deficit, not a fixed number copied from someone else’s plan.
- A deficit of roughly 500 calories a day corresponds to about 1 lb (0.45 kg) of weight loss per week under the widely used 3,500-calorie-per-pound approximation.
- The 3,500-calorie rule is a simplification that becomes less accurate over longer periods, because maintenance calories fall as bodyweight drops.
- Commonly cited minimum intakes are around 1,200 calories a day for women and 1,500 for men, and these are general guidance rather than universal medical thresholds.
- A deficit that’s too aggressive tends to cost muscle alongside fat and is the most common reason people abandon a plan within a few weeks.
Start With Maintenance, Not a Guess
Every valid calorie target starts from the same place: how much you burn in a normal day. That figure is your Total Daily Energy Expenditure, or TDEE, and it’s your basal metabolic rate multiplied by an activity factor that reflects how you actually spend your time.
Most calculators estimate BMR using the Mifflin-St Jeor equation, which takes height, weight, age, and sex. That gives you what you’d burn lying still all day. Multiplying by an activity factor between about 1.2 (desk job, minimal exercise) and 1.9 (physical job plus daily training) produces TDEE. If those terms are blurring together, our breakdown of BMR versus TDEE untangles them properly, because using the wrong one is the single most common setup error in the whole exercise.
Say your TDEE comes out at 2,400 calories. That’s your maintenance. Eat that and, roughly speaking, your weight holds. Everything from here is subtraction.
Setting the Deficit
A calorie deficit means eating below maintenance. The conventional starting point is 500 calories a day, which under the standard approximation produces about a pound of loss per week. For our 2,400-calorie example, that’s a target of 1,900.
Two guardrails are worth applying to whatever number you land on.
The first is proportional: a deficit somewhere around 15-25% of TDEE tends to be sustainable, while going much past 25% starts trading away muscle and adherence. For someone with a 2,400 TDEE, that’s a deficit of roughly 360 to 600 calories. For someone with a 3,200 TDEE, the same percentages allow a much larger absolute deficit, which is why fixed-number advice fails at the extremes.
The second is directional: aim for roughly 0.5-1% of bodyweight lost per week. Heavier people can safely lose faster in absolute terms; someone already lean cannot, and pushing it just accelerates muscle loss.
Deficit Size and Expected Rate
Using a 2,400-calorie maintenance level as the example, here’s how deficit size maps to expected loss.
| Daily deficit | Daily target | % of TDEE | Approx. weekly loss | Practical read |
|---|---|---|---|---|
| 250 cal | 2,150 | 10% | 0.5 lb / 0.23 kg | Slow, very sustainable |
| 500 cal | 1,900 | 21% | 1 lb / 0.45 kg | Standard recommendation |
| 750 cal | 1,650 | 31% | 1.5 lb / 0.68 kg | Aggressive, harder to hold |
| 1,000 cal | 1,400 | 42% | 2 lb / 0.9 kg | Rarely advisable unsupervised |
Notice the bottom row lands at 1,400 calories, which is below the commonly cited floor for men and close to it for women. That’s the mechanism by which “just eat less” advice quietly becomes bad advice: the arithmetic keeps working long after the plan stops being reasonable.
Where the 3,500-Calorie Rule Breaks Down
The rule that 3,500 calories equals a pound of fat comes from an estimate published by researcher Max Wishnofsky in 1958, and it’s been carried in diet guidance ever since. It’s a useful approximation for short horizons and a poor one for long ones.
The reason is that it treats maintenance as fixed while your body changes. Lose 20 lb and your TDEE falls, because a smaller body costs less to run and moving it around burns less. The 500-calorie deficit that produced a pound a week at the start produces less than that six months in, not because the plan failed but because the maths quietly shifted underneath it. Linear projections from the 3,500 rule consistently overestimate loss over a year or more, which is why people hit a wall well before the spreadsheet said they would.
The practical fix is straightforward: recalculate your TDEE every 5-10 kg of change rather than setting a target once and defending it for a year.
Get Your Own Target
Enter your height, weight, age, sex, and activity level in the CalcRange Calorie Calculator to get your maintenance figure and deficit targets in one step. For a realistic sense of timeline before you start, our guide to how much weight you can actually lose in a month sets expectations against what the maths supports.
The Floor You Shouldn’t Drop Below
The figures usually quoted are about 1,200 calories a day for women and 1,500 for men. These are general guidance rather than hard medical cutoffs, and they exist for a practical reason: below roughly that level it becomes genuinely difficult to hit protein, fibre, and micronutrient requirements from food, regardless of how carefully you plan.
There’s a second reason to respect the floor, and it’s less about nutrition than about physics. Your BMR is what your organs need to function. Consistently eating well beneath it pushes the body toward breaking down muscle for fuel alongside fat, and muscle loss lowers your TDEE further, which makes the next phase harder. It’s a mechanism that punishes impatience specifically.
Very low calorie diets below these thresholds do exist as legitimate clinical interventions, but they’re medically supervised for a reason and aren’t a DIY option.
Why the Number Stops Working
Three things account for most stalls, and none of them mean your metabolism is broken.
TDEE fell and the target didn’t. Covered above, and it’s the most common one by a distance.
Intake crept up. Not deliberately. Portion estimates drift, cooking oil goes unlogged, food labels carry legal tolerances of up to 20% either way. A plan that assumes perfect measurement is measuring something other than what you ate. Our piece on how accurate calorie counts really are covers the size of that gap.
Non-exercise movement dropped. This one is nearly invisible. Under sustained restriction, people fidget less, walk a little slower, take the lift more often. Nobody decides to do this. It can quietly erase a few hundred calories of deficit without a single logged change.
The fix for all three is the same: measure the trend over two to three weeks rather than reacting to daily scale noise, and adjust the target when the trend actually flattens.
Frequently Asked Questions
How many calories should I eat to lose weight?
Take your maintenance calories (TDEE) and subtract a deficit of roughly 15-25%. For someone with a 2,400-calorie maintenance level, that means eating around 1,800 to 2,040 calories a day, which corresponds to roughly 0.5 to 1 lb of loss per week.
Is 1,200 calories a day enough to lose weight?
It will produce a deficit for most adults, but it’s near the commonly cited minimum for women and below the usual guidance for men. Whether it’s appropriate depends entirely on your maintenance level; for someone with a high TDEE it’s an unnecessarily severe deficit that tends to cost muscle and adherence.
How much of a calorie deficit do I need to lose 1 lb a week?
About 500 calories a day, based on the widely used approximation that a pound of fat represents roughly 3,500 calories. This holds reasonably well over weeks but overestimates loss over longer periods, since maintenance calories fall as you lose weight.
Why did my weight loss stop even though I’m eating the same amount?
Usually because your TDEE fell as your bodyweight dropped, so the same intake is now a smaller deficit. Unlogged intake creep and reduced non-exercise movement are the other two common causes. Recalculating your target every 5-10 kg of change addresses the first.
Can I eat below my BMR to lose weight faster?
It’s generally a poor trade. BMR is the energy your organs need at rest, and consistently eating beneath it tends to push the body toward burning muscle alongside fat, which lowers your maintenance level further and makes continued loss harder.
How many calories should I eat to lose weight without exercise?
The same method applies, but your TDEE will be lower because you’d use a sedentary activity multiplier of around 1.2 rather than a higher one. That means a smaller absolute deficit is available before you hit the recommended intake floor.
The Bottom Line
How many calories you should eat to lose weight is your own maintenance number minus a deficit you can actually live with, typically 15-25% of TDEE. Skip the fixed numbers you’ve seen quoted, respect the intake floor, and recalculate as your bodyweight changes rather than defending a target you set months ago. The plan that works is almost never the fastest one on paper.
Health disclaimer: This article is general information, not medical or dietetic advice. Calorie needs vary with medical conditions, medications, pregnancy, and eating disorder history. Speak to a qualified healthcare professional or registered dietitian before starting a significant calorie deficit.
Last reviewed: August 2026