In short: a 40 year old woman needs about 1,200 to 2,300 calories a day to lose weight, depending on her weight and how active she is. A 70 kg woman who is moderately active needs about 1,721 calories a day. Find your weight and activity level in the tables below.
- The answer depends on two things: your weight and your activity level. A 55 kg sedentary woman needs about 1,200 calories a day to lose weight, while a 90 kg very active woman needs about 2,291.
- Every number in this post comes from the site’s own calculators, which use the Harris-Benedict Revised equation. A 40 year old woman who is 165 cm tall has a BMR of 1,433 calories a day at 70 kg, and a TDEE of 2,221 if she is moderately active.
- The weight loss target is your TDEE minus 500 calories, which works out to about half a kilo of weight loss a week. The target never goes below 1,200 calories a day, which is the floor used in this post.
- Activity level changes the answer more than weight does. Going from sedentary to very active adds about 750 calories a day to a 70 kg woman’s burn, so setting your activity level honestly matters more than weighing yourself to the gram.
- Recalculate every time you lose about 5 kg, because a lighter body burns fewer calories. A target that worked at 80 kg will stall at 75 kg if you never update it.
Introduction
How many calories should a 40 year old woman eat to lose weight? Most answers online are a single number that cannot possibly fit everyone, or a calculator that hides how it got its answer. A 55 kg woman who sits at a desk all day and a 90 kg woman who walks 15,000 steps a day do not burn anything like the same calories.
This post gives you the full table instead: your calories by weight, from 55 to 90 kg, and by activity level, from sedentary to very active, for a 40 year old woman who is 165 cm tall. Every number was worked out with the same equation the site’s own calculators use, and the worked example shows the maths step by step, so you can check it yourself.
One warning: many calculators online use a different equation, called Mifflin-St Jeor. The numbers here use the Harris-Benedict Revised equation, because that is what the TDEE calculator and the BMR calculator on this site use. The two give answers a small amount apart, usually within about 5%, so if another site gives you a slightly different number, that is probably why.
How the Numbers Were Worked Out
There are three steps, and they are the same three steps the site’s calculators follow.
Step 1: BMR, what you burn at rest. Your basal metabolic rate is the energy your body uses just to stay alive. For women, the Harris-Benedict Revised equation is: BMR = 447.593 + 9.247 x weight in kg + 3.098 x height in cm – 4.330 x age. Roza and Shizgal published this revised version in 1984.
Step 2: TDEE, what you actually burn in a day. Your total daily energy expenditure is your BMR multiplied by an activity factor: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active. This is your maintenance level.
Step 3: the weight loss target. Subtract 500 calories from your TDEE. A 500 calorie daily deficit is 3,500 calories over a week, and 1 kg of body fat holds about 7,700 calories, so 3,500 is about 0.45 kg, or about half a kilo a week. The target never goes below 1,200 calories a day: below that, it gets hard to get enough nutrients, and most women feel tired and hungry all the time.
All three steps were run for a 40 year old woman, 165 cm tall, at weights from 55 to 90 kg. If your height is different, use the TDEE calculator: the method is identical, only your height changes.
Worked Example: A 70 kg Woman, Moderately Active
Here is the full calculation, step by step, so you can see exactly where the numbers come from.
BMR: 447.593 + 9.247 x 70 + 3.098 x 165 – 4.330 x 40. That is 447.593 + 647.29 + 511.17 – 173.2, which comes to 1432.85, rounded to 1,433 calories a day. That is what her body burns at complete rest.
TDEE: she is moderately active, so multiply by 1.55. 1432.85 x 1.55 = 2220.9, rounded to 2,221 calories a day: her maintenance level.
Weight loss target: 2221 – 500 = 1,721 calories a day. At that level she should lose about half a kilo a week, on average, though the scale will not move evenly: water, food, and her cycle can move it by a kilo or more in a day, so judge it over a month, not a morning.
The Full Table: BMR and TDEE by Weight and Activity
This table is for a 40 year old woman, 165 cm tall. Find your weight, then read across to your activity level. BMR is what you burn at rest, and TDEE is what you burn in a day, which is your maintenance level.
| Weight | BMR | TDEE sedentary | TDEE lightly active | TDEE moderately active | TDEE very active |
|---|---|---|---|---|---|
| 55 kg | 1,294 | 1,553 | 1,779 | 2,006 | 2,232 |
| 60 kg | 1,340 | 1,608 | 1,843 | 2,078 | 2,312 |
| 65 kg | 1,387 | 1,664 | 1,907 | 2,149 | 2,392 |
| 70 kg | 1,433 | 1,719 | 1,970 | 2,221 | 2,472 |
| 75 kg | 1,479 | 1,775 | 2,034 | 2,293 | 2,551 |
| 80 kg | 1,525 | 1,830 | 2,097 | 2,364 | 2,631 |
| 85 kg | 1,572 | 1,886 | 2,161 | 2,436 | 2,711 |
| 90 kg | 1,618 | 1,941 | 2,224 | 2,508 | 2,791 |
Two patterns matter. BMR rises by about 46 calories for every 5 kg of weight. And activity matters more than weight: a 55 kg very active woman burns 2,232 calories a day, more than a 90 kg sedentary woman at 1,941. Set your activity level wrong and your target will be wrong by far more than any weighing error.
The Full Table: Calories to Lose Weight
Each number is the TDEE above minus 500 calories, with a floor of 1,200 a day. The floor applies to the three lightest sedentary rows.
| Weight | Sedentary | Lightly active | Moderately active | Very active |
|---|---|---|---|---|
| 55 kg | 1,200 | 1,279 | 1,506 | 1,732 |
| 60 kg | 1,200 | 1,343 | 1,578 | 1,812 |
| 65 kg | 1,200 | 1,407 | 1,649 | 1,892 |
| 70 kg | 1,219 | 1,470 | 1,721 | 1,972 |
| 75 kg | 1,275 | 1,534 | 1,793 | 2,051 |
| 80 kg | 1,330 | 1,597 | 1,864 | 2,131 |
| 85 kg | 1,386 | 1,661 | 1,936 | 2,211 |
| 90 kg | 1,441 | 1,724 | 2,008 | 2,291 |
Read your row and your column, and that is your daily target. A 70 kg moderately active woman eats about 1,721 calories a day, and an 80 kg lightly active woman eats about 1,597. If your weight falls between two rows, take the nearer one: the difference is only about 50 to 60 calories.
How to Pick Your Activity Level Honestly
This is where most people get their number wrong: each step up adds about 200 to 250 calories a day to your target.
Sedentary (1.2): a desk job, little walking, no regular exercise. You sit most of the day and your steps stay under about 5,000.
Lightly active (1.375): light exercise one to three days a week, or a job that keeps you on your feet.
Moderately active (1.55): moderate exercise three to five days a week, or a physical job plus some exercise. This is where most women who go to the gym regularly and walk daily sit.
Very active (1.725): hard exercise six or seven days a week, or a very physical job plus training. This is the smallest group, and the one people most often claim when they should not: if you train three times a week and sit the rest of the time, you are moderately active, not very active.
When in doubt, pick the lower level. A target that is a little too low will still produce weight loss, and you can raise it if you feel tired or hungry all the time. A target that is too high will stall you. Our weight loss goal calculator turns your target into a dated plan with a finish date.
Why 40 Is Different From 30
Weight loss at 40 is not harder because of some sudden change on your birthday. It is harder because several slow changes have added up for a decade: muscle is lost with age, roughly 3 to 8 percent per decade after 30, and muscle burns more calories than fat, so losing muscle lowers your BMR. At the same time, many women move less than they did at 30. Less muscle and less movement mean a lower TDEE, and a lower target for the same rate of loss.
Perimenopause can add to this: hormone changes can shift where fat is stored, towards the middle, and can disturb sleep, which disturbs appetite the next day. None of this makes weight loss impossible. It makes the maths less forgiving.
The response is the same at any age: protect muscle and keep moving. Strength training two or three times a week defends the muscle that keeps your BMR up. Protein helps too: the site’s protein calculator uses 1.2 to 1.6 g of protein per kg of body weight a day for weight loss, and our protein intake calculator gives you a personal target. An extra 3,000 steps a day is roughly 100 to 150 calories of burn, which can move you from one activity level to the next.
Why the 1,200 Calorie Floor Matters
Three rows in the table hit the 1,200 floor: sedentary women at 55, 60 and 65 kg, whose TDEE minus 500 would be 1,053, 1,108 and 1,164 calories. That is deliberate. Below about 1,200 calories a day it gets very hard to get enough protein, fibre, vitamins and minerals from food, and most women feel tired, cold, and hungry all the time. A plan that makes you feel awful is a plan you will quit. If your target hits the floor, raise your activity instead of cutting food further: add a daily walk and your TDEE rises, so your target rises too. A 65 kg sedentary woman at 1,200 calories becomes a 65 kg lightly active woman at 1,407 calories, for the same rate of loss. If you have a medical condition, take medication, or have a history of disordered eating, talk to your doctor before starting any calorie target. The floor of 1,200 is a general guide, not a prescription.
What to Eat at Your Target
The number is only half the plan. Build each meal around protein, eggs, Greek yoghurt, chicken, fish, lentils, or tofu, with vegetables filling half the plate and a modest portion of carbohydrate alongside. Protein keeps you full longer and protects muscle. Aim for 1.2 to 1.6 g per kg a day, which for a 70 kg woman is about 84 to 112 g. Keep some foods you enjoy in the plan, and track with the calories calculator for the first few weeks: most people find their real intake is 200 to 300 calories above what they thought.
When to Recalculate
Your target is not permanent. Every kilo you lose lowers your BMR a little, because a lighter body costs less energy to run. A target that worked at 80 kg may stall at 70 kg if you never update it. Recalculate every time you lose about 5 kg, or once a month: go back to the TDEE calculator, enter your new weight, and take the new target. A plateau is often just an out-of-date target.
Frequently Asked Questions
How many calories should a 40 year old woman eat to lose weight?
It depends on weight and activity, but for a 40 year old woman who is 165 cm tall, the range is about 1,200 to 2,291 calories a day. A 70 kg moderately active woman needs about 1,721 calories a day. Find your weight and activity level in the tables in this post, or use the TDEE calculator for your exact height and weight.
Is 1,200 calories a day safe for a 40 year old woman?
1,200 calories is used in this post as a floor, not a goal: no target goes below it. Below about 1,200 calories a day it gets hard to get enough nutrients, and most women feel tired and hungry. If your target hits the floor, raising your activity is usually better than eating less. Talk to your doctor before starting any low calorie target, especially if you have a medical condition or take medication.
Why does my friend lose weight on more calories than me?
Because her TDEE is higher. She may be heavier, taller, younger, or more active, and any of those raises her burn. A 90 kg very active woman burns 2,791 calories a day, while a 55 kg sedentary woman burns 1,553. That is a gap of over 1,200 calories before either of them has eaten anything. Compare your target with your own numbers, not with someone else’s.
How fast will I lose weight on a 500 calorie deficit?
About half a kilo a week, on average. A 500 calorie daily deficit is 3,500 calories over a week, and 1 kg of body fat holds about 7,700 calories, so 3,500 calories is about 0.45 kg. The scale will not move evenly, because water, food, and your cycle can move it by a kilo or more in a day, so judge your progress over a month, not a morning.
Do I need to recalculate my calories as I lose weight?
Yes. Every kilo you lose lowers your BMR a little, because a lighter body costs less energy to run. Recalculate every time you lose about 5 kg, or once a month. A target that worked at 80 kg will stall at 70 kg if you never update it, and a plateau is often just an out-of-date target.
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Sources
- Harris JA, Benedict FG. “A Biometric Study of Human Basal Metabolism.” Proceedings of the National Academy of Sciences. 1918;4(12):370-373. The original Harris-Benedict equation. https://doi.org/10.1073/pnas.4.12.370
- Roza AM, Shizgal HM. “The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass.” American Journal of Clinical Nutrition. 1984;40(1):168-182. The revised equation used by this site’s calculators. https://doi.org/10.1093/ajcn/40.1.168
- Weight Insider. TDEE calculator and BMR calculator. Both use the Harris-Benedict Revised equation. Every number in this post was computed with the same equation and verified by recomputation.
Medical Disclaimer
This article is general information only. It is not medical advice, and it is not a substitute for advice from a qualified health professional. Calorie targets in this post are worked examples for a 40 year old woman who is 165 cm tall, using the Harris-Benedict Revised equation, and your own needs may differ. Talk to your doctor, or a registered dietitian, before starting a calorie deficit, especially if you have a medical condition, are taking medication, are pregnant or breastfeeding, or have a history of disordered eating.