The quickest way to get your own range is the meal plan builder, which does the sums below and turns them into a week of meals. Here is how the numbers work.
How are daily calorie needs worked out?
In two steps. First, your resting energy: what your body burns to keep running if you did nothing all day. The widely used Mifflin-St Jeor equation estimates it from your weight, height, age and sex:
- Men: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
- Women: 10 × weight in kg + 6.25 × height in cm − 5 × age − 161
Second, you multiply that by a physical activity level, or PAL, which reflects how much you move in a typical day.
What activity level should you use?
The joint FAO, WHO and UNU report on human energy requirements groups lifestyles into three bands:
| Lifestyle | PAL | What it looks like |
|---|---|---|
| Sedentary or light activity | 1.40–1.69 | Desk job, little exercise |
| Active or moderately active | 1.70–1.99 | On your feet a lot, or exercise most days |
| Vigorous or vigorously active | 2.00–2.40 | Physical job, or hard training most days |
The report notes that "PAL values > 2.40 are difficult to maintain over a long period of time." Because each band is a range, your answer is a range too, not one exact number.
What does that look like for a real person?
Take a 40-year-old woman who is 165 cm tall, weighs 68 kg and works at a desk. Her resting energy is 10 × 68 + 6.25 × 165 − 5 × 40 − 161, about 1,350 kcal a day. Multiplied by 1.40 to 1.69, her daily needs come to roughly 1,900 to 2,300 kcal.
Equations like this are built from averages. Real needs vary between people, so treat the range as a starting point and adjust it if your weight drifts.
How many calories should you cut to lose weight?
Less than many people expect. The 2013 AHA, ACC and The Obesity Society guideline on managing overweight and obesity describes an energy deficit of 500 or 750 kcal a day, or a daily intake of 1,200 to 1,500 kcal for women and 1,500 to 1,800 kcal for men. It keeps very low calorie diets, under 800 kcal a day, for medically supervised settings.
A smaller cut is easier to keep up. Keeping vegetables and protein generous while trimming portions of starchy foods is one practical way to eat less without feeling deprived. For the protein side, see how much protein you need a day.
When should you not count calories?
- If you have had an eating disorder, or feel anxious or out of control around food. Regular, varied meals matter more than numbers, and a doctor or registered dietitian can help.
- If your BMI is under 18.5, which the World Health Organization classes as underweight.
- If you are pregnant, breastfeeding or live with a long-term condition. Check with your doctor or midwife first.
For what to put on the plate once you know your range, see how to plan a week of healthy meals. The full guide to nutrition covers the rest.
