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How to Calculate a Calorie Deficit for Fat Loss (Mifflin–St Jeor)

1 min read

Fat loss starts with an accurate calorie target — not a random 1,200 kcal plan from social media. The Mifflin–St Jeor equation is widely used by coaches because it estimates resting energy expenditure from your age, height, weight, and sex, then adjusts for activity.

Step 1: Estimate your BMR

For men: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5. For women: substitute −161 at the end. This gives you basal metabolic rate (BMR) — calories burned at rest.

Step 2: Multiply by activity

Sedentary ×1.2, lightly active ×1.375, moderately active ×1.55, very active ×1.725. The result is maintenance calories.

Step 3: Apply a deficit

Most people do well with a 15–25% deficit (roughly 300–500 kcal below maintenance). Pair it with 1.8–2.2 g protein per kg bodyweight to protect muscle while dieting.

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