How we calculate it
From your expenditure to your calories, in four steps
How we calculate it
- What you use at rest: using the Mifflin-St Jeor equation, which takes your sex, age, weight and height 1.
- What you use in a day: we multiply that figure by your activity factor. We use 1.4 if you are sedentary, 1.55 if you train 1-3 days a week, 1.75 if you train 4-5 days and 2 if you train every day or have a physical job, within the FAO and WHO ranges 2.
- Your pace: between 0.5% and 1% of your body weight per week 3. In elite athletes, losing weight more slowly preserved muscle mass and strength better 5.
- Your deficit: each kilo of body weight lost is roughly equivalent to about 7,700 kcal 4. We spread it across the 7 days of the week.
- Your limit: we never suggest eating below your resting expenditure. If your pace would require it, we tell you how much you would lose eating that amount.
- Your protein: from 1.8 to 2.5 g per kilo of body weight a day, roughly equivalent to the recommendations for preserving muscle in a deficit 3.
Same diet
Sleep and your deficit: what you lose by how much you sleep
Why sleep counts as much as diet
In a study with the same diet, spending 5.5 hours in bed instead of 8.5 meant that less than half as much fat was lost, and more lean mass 6. If you sleep too little, your deficit does less for you. Check your rest with the sleep test.
What about supplements?
Diet, protein, strength training and sleep come first.
You will find the complete plan in the guide to getting leaner and all the fat burners compared in fat burners: which ones work.
Frequently asked questions
How many calories should I eat to lose fat?
Your daily expenditure minus your deficit. At a pace of 0.5-1% of your body weight per week, if you weigh 80 kg that is about 440-880 kcal less a day. The calculator does it for you using your sex, age, weight, height and activity level.
What is a calorie deficit?
Eating fewer calories than you use. Your body makes up the difference from its reserves, mainly fat if you eat enough protein and do strength training.
How much weight is it healthy to lose per week?
Between 0.5% and 1% of your body weight. In athletes, the slower pace preserved muscle mass and strength better.
Why am I not losing weight if I am in a deficit?
Formulas are an estimate, and weight varies from day to day with water and food. Look at the average of several mornings over 2 weeks: if it does not go down, take off another 100-200 kcal a day or add more activity.
Which supplements help when you are getting leaner?
Protein helps you reach your daily target. “Protein contributes to the maintenance of muscle mass.” A varied and balanced diet and a healthy lifestyle are important.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. View publication
- FAO, OMS, UNU. Human energy requirements: report of a Joint FAO/WHO/UNU Expert Consultation. FAO Food and Nutrition Technical Report Series 1. Roma: FAO; 2004. View publication
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. View publication
- Hall KD. What is the required energy deficit per unit weight loss? Int J Obes. 2008;32(3):573-576. View publication
- Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. View publication
- Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435-441. View publication