Calorie and macro calculator

First, what you burn at rest, with the Mifflin-St Jeor equation: in the review by Frankenfield et al., it’s the one that most often comes close to what’s measured in the lab. Then I multiply it by your activity level, using the FAO and WHO levels.

To lose fat I take off 20%, which is my own choice, and to build muscle I add 10%, the minimum Iraki et al. suggest. With typical figures, taking off 20% means losing between 0.5% and 1% of your body weight a week, the pace Helms et al. recommend so you don’t lose muscle along the way.

Protein goes per kilo of body weight: 2.2 g to lose fat and 1.8 g otherwise. Fat is 25% of the calories and the rest is carbs. If your body mass index is over 30, I work out protein from the weight you’d have at 30 rather than your total weight.

Any equation is off by 10% or more for some people, either way. That’s why the number is a ballpark: what really matters is how your body responds when you put it into practice.

If you want to be a lion, you can’t eat like a bird. But everyone has their own story, and that context shapes their relationship with food: this is an estimate, and I adjust the plan to your day-to-day life.

If you’re pregnant or breastfeeding, if you have or have had an eating disorder, or if you have a condition that affects what you eat, don’t go by this calculator: talk to your doctor. And if counting calories makes you anxious, you don’t need to do it to make progress.