How Many Calories Should I Eat a Day? Work Out Your Number

How many calories should you eat a day? To stay at the same weight, the NHS gives about 2,500 kcal a day for an average man and 2,000 kcal for an average woman. Your own number can sit a few hundred kcal either side, because it depends on your age, size and how much you move. You can work it out in four steps: resting energy, activity, your goal, and a two-week check.

Key takeaways

• The number that keeps your weight steady is called maintenance calories. Start there.
• Work it out from your weight, height and age, then multiply by an activity factor.
• To lose weight, eat a bit less than maintenance. To gain, a bit more.
• Treat the result as a starting point and adjust it from two weeks of real weight and food records.

How many calories should you eat a day?

Real numbers run from about 1,700 to 3,100 kcal a day, as the four worked examples further down show. Smaller, older or less active people sit at the low end; tall, young or very active people sit at the high end. The NHS uses 2,000 kcal for women and 2,500 kcal for men as rough averages. To get your own, multiply your resting energy (what you burn lying still) by an activity factor, as in the steps below.

Step 1: Find your resting energy

Resting energy is what your body burns for breathing, circulation and keeping warm. The Mifflin-St Jeor equation estimates it. Its authors built it in 1990 from measurements of 498 healthy adults aged 19 to 78. A systematic review by the Academy of Nutrition and Dietetics found it the most reliable of the common equations for healthy adults.

If you think in pounds and inches: divide pounds by 2.2 for kg, and multiply inches by 2.54 for cm.

Step 2: Multiply by your activity

Walking, working and training use energy on top of your resting energy. The FAO, WHO and United Nations University expert report describes three bands of daily activity:

Pick the middle of your row if you are unsure. Values above 2.40 are hard to keep up for long, according to the same report.

Four worked examples

These are examples calculated with the formulas above, not real people. Numbers are rounded to the nearest 10 kcal.

The first example is below the NHS average for women and the last is well above the NHS average for men. Most people sit above or below these averages, so a result away from them is normal.

Step 3: Set your goal

Maintenance holds your weight. To lose weight, eat below it, and to gain, eat above it. For a cut, the 2013 US obesity guideline recommends a daily cut of 500 to 750 kcal. Our calories for weight loss guide shows the steps, and what a calorie deficit is explains why a bigger cut is not always better. For an average adult with overweight, a 500 kcal cut averages about 0.2 kg a week over the first year, because the pace slows as you lose weight. For seven days of meals built around a target, see the calorie deficit diet plan. For protein at any calorie level, see how much protein you need per day. Cal Clark sets calorie and macro targets for the goal you pick: lose weight, gain mass, fuel training or stay healthy. It is coming soon to iOS and Android: join the waitlist.

If you would rather skip the arithmetic, the calorie calculator and the TDEE calculator do Steps 1 and 2 for you.

Step 4: Check it against real life

A formula gives an average for people of your size and age. It was tested on healthy adults, and individual estimates can still be well off. Run a two-week test:

1. Log everything you eat and drink, and weigh yourself each morning.
2. Compare your average weight in week 1 and week 2.
3. If your weight held steady, your target is your maintenance. If it moved, change the target by a small step and test again.

In a small study in the New England Journal of Medicine, ten people with obesity who said they could not lose weight on a low intake under-reported what they ate by 47% on average. It is one small group, but it shows that records from memory can miss a lot. Logging each meal as you eat it, and adding the oil and sauces, helps.

Where this does not work

• These numbers are for healthy adults. They do not fit pregnancy, breastfeeding or anyone under 18.
• If you have a thyroid condition, diabetes, a long-term illness or take medication that affects weight, ask your doctor or a registered dietitian for your target.
• If you have had an eating disorder, do not work out calorie targets alone.
• The lowest fixed intakes in the US guideline are 1,200 to 1,500 kcal for women and 1,500 to 1,800 kcal for men. Talk to a doctor before eating less than that.
• A formula cannot see muscle mass. A very muscular person burns more than the formula says.

Frequently asked questions

How many calories should a woman eat a day?

The NHS gives about 2,000 kcal a day as the average for a woman to hold her weight. The worked examples above give about 1,690 kcal for a smaller woman with a desk job and about 2,190 kcal for a woman who walks most days. Use the steps above for your own figure.

How many calories should a man eat a day?

The NHS gives about 2,500 kcal a day as the average for a man. The worked examples above give about 2,840 kcal for a 40-year-old man with a desk job who trains twice a week and about 3,080 kcal for a younger man who trains most days.

Is 1,200 calories a day enough?

The US obesity guideline lists 1,200 to 1,500 kcal a day as the lowest fixed intake for women, so 1,200 is the floor, not a target. It is below the maintenance of every example on this page. Work out your own maintenance first and cut moderately from there.

Do I need to eat back the calories I burn exercising?

Usually not. The activity factor in Step 2 already includes your regular exercise, so adding workouts again counts them twice.

Do my calorie needs change as I get older?

Yes. The age term in the formula lowers your resting energy by about 50 kcal for every ten years, so recalculate with your current age and weight every few months.

Summary

The NHS averages are 2,000 kcal a day for women and 2,500 kcal for men, and the examples above show how far real numbers can sit from them. Work out your own number from resting energy times activity, then test it for two weeks and adjust. Once you know it, set your goal from there: losing weight, protein and plateaus are the next pages to read.

Sources

• NHS. Understanding calories.
• Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
• Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc, 2005.
• FAO, WHO, UNU. Human energy requirements, chapter 5: physical activity levels. 2001.
• Jensen MD, Ryan DH, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation, 2014.
• Hall KD, Sacks G, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011.
• Lichtman SW, Pisarska K, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med, 1992.

Related

• How many calories should I eat to lose weight?
• What is a calorie deficit, and how big should yours be?
• Why you stopped losing weight