Macro Calculator for Weight Loss

How this weight loss macro calculator works

This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies by an activity factor to determine your Total Daily Energy Expenditure (TDEE). A moderate calorie deficit of approximately 550 calories per day is applied, targeting about 0.5 kg (roughly 1 lb) of fat loss per week. This rate is widely recommended by nutrition researchers as sustainable and safe for most adults.

The calculator sets a minimum calorie floor of 1,500 kcal for men and 1,200 kcal for women to ensure nutritional adequacy. Protein is set at 2.0 grams per kilogram of body weight during a deficit, which is higher than maintenance, to help preserve lean muscle mass while losing fat. Fat is set at 25% of total calories, and the remaining calories are allocated to carbohydrates.

Why protein matters more during a deficit

When you eat fewer calories than you burn, your body can break down muscle tissue for energy alongside fat. Higher protein intake (1.6-2.4 g/kg) has been shown in multiple meta-analyses to significantly reduce muscle loss during caloric restriction, especially when combined with resistance training. This calculator uses 2.0 g/kg as the default, which sits in the middle of the evidence-based range.

Tips for successful fat loss

• Track consistently: Research shows that people who track food intake lose more weight than those who do not, even without perfect accuracy
• Prioritize protein: Hit your protein target first each day, then fill in carbs and fats around it
• Lift weights: Resistance training is the most effective way to preserve muscle during a calorie deficit
• Be patient: Aim for 0.5-1% of body weight lost per week. Faster loss increases muscle loss and metabolic adaptation

Other goals

Already at your target weight? Switch to the maintenance macro calculator to find your sustaining calorie level. Looking to build muscle? Try the muscle gain macro calculator for a calculated caloric surplus.