How to Work Out Your Calorie Deficit (Without Starving Yourself)

How Many Calories Do I Need a Day? A Simple Step-by-Step Calculation

Your daily calorie need is not a magic number from an app. It is your basal metabolic rate, multiplied by how active you are, plus or minus what your goal requires. Here is how to calculate it yourself in three steps.

Written by Velion Physique. I have done nutrition coaching since 2019, alongside working as a personal trainer with five trainer licences.

The Calorie Deficit Handbook: Find Your Number, Keep the Muscle

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The Calorie Deficit Handbook: Find Your Number, Keep the Muscle

Work out your maintenance calories, set a deficit you can sustain, and keep your muscle while losing fat. Instant PDF download. · $21.00

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Short on time? The free fitness check does the calculation for you in 60 seconds – calories, protein, fat, carbs and water.

Step 1: Your basal metabolic rate (BMR)

Your BMR is what your body burns at complete rest. The most widely used estimate is the Mifflin-St Jeor formula:

  • Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
  • Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

Step 2: Multiply by your activity level

Activity Factor
Desk job, little exercise 1.2
Desk job, training 2–3 times a week 1.375–1.45
Training 4–5 times a week 1.55
Physical job or daily hard training 1.7+

Be honest here. Most people overestimate their activity – one hour of training does not cancel out eight hours of sitting.

Step 3: Adjust for your goal

  • Lose fat: about 300–500 kcal below your maintenance calories.
  • Build muscle: about 200–300 kcal above maintenance.
  • Maintain: stay at maintenance and focus on training and protein.

Two worked examples

Man, 30, 180 cm, 80 kg, trains 4 times a week: BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal. × 1.55 = about 2,760 kcal maintenance. For muscle gain: about 3,000 kcal.

Woman, 30, 168 cm, 65 kg, desk job, trains twice a week: BMR = 650 + 1,050 − 150 − 161 = 1,389 kcal. × 1.375 = about 1,900 kcal maintenance. For fat loss: about 1,450–1,600 kcal.

The most common mistakes

  • Treating the number as exact. Every formula is an estimate. Weigh yourself for 2–3 weeks and adjust by 100–200 kcal if your weight does not move as planned.
  • Too big a deficit. Cutting 1,000 kcal often costs muscle, energy and sleep. Slower usually works better.
  • Forgetting protein. In a deficit, enough protein is what protects your muscle. See how much protein you need.

Next steps

More detail on fat loss: how to calculate your calorie deficit · the difference between resting and total burn: BMR explained · splitting your calories: how to calculate your macros.

Want every step done for you? The Calorie Deficit Handbook walks you through finding your number and adjusting it week by week.

General information, not medical or dietetic advice. With medical conditions, pregnancy or a history of eating disorders, please plan your intake with a doctor or dietitian.

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