How to calculate your diet's calories and macros (and build a shopping list)

1. Your daily energy use

Start with your basal metabolic rate (Mifflin-St Jeor equation, using sex, age, weight and height) and multiply it by an activity factor of 1.2 to 1.9. The result is an estimate: adjust it after 2 to 3 weeks based on how your weight and waist change.

2. Deficit or surplus

For fat loss, a deficit of 10–25% of your energy use is sustainable and protects muscle; you shouldn't go below roughly 1200 (women) or 1500 (men) calories per day without professional support. To build muscle, 5–10% above your energy use is enough.

3. Splitting your macros

Protein first: 1.6 to 2.2 g per kg of body weight if you train. Fat: at least 20% of calories. Carbs make up the rest and fuel your training. Protein and carbs have 4 kcal per gram; fat has 9.

4. Reading the label

Nutrition labels give values per 100 g. For 150 g, multiply by 1.5. Weigh food raw or cooked to match the table you use, and always stick to the same method.

With FitHandy, no maths

Let the app generate your diet or enter your own: type the foods and grams and instantly see the calories and macros of each meal and the whole day, compared with your target. Foods not on the list use the per-100 g values from the label. When you save, your weekly shopping list is ready.

Frequently asked questions