5:2 & 4:3 Calorie Cycling Calculator

What Are the 5:2 and 4:3 Protocols?

The 5:2 and 4:3 calorie cycling protocols alternate between normal-calorie days and reduced-calorie days during the week. In 5:2, you eat normally for 5 days and reduce calorie intake on 2 non-consecutive days. In 4:3, there are 3 reduced-calorie days per week.

Reduced-calorie days typically target 500 kcal (for women) or 600 kcal (for men), or alternatively 25% of your estimated TDEE. The remaining days are eaten at normal maintenance levels.

How This Calculator Works

This tool uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies by your activity level to get Total Daily Energy Expenditure (TDEE). It calculates both normal-day and restricted-day calories with full macro breakdowns.

For daily time-restricted eating windows (16:8, 18:6, etc.), use the Intermittent Fasting Calculator. For daily calorie cycling with high/medium/low days, try the Zig-Zag Calorie Calculator.

Protein Prioritization on Restricted Days

On restricted-calorie days, this calculator prioritizes protein intake (up to 50% of calories from protein). Higher protein intake during calorie restriction helps maintain lean body mass. On normal days, protein is set at 1.6 g/kg bodyweight, aligned with current sports nutrition recommendations.

For detailed macro planning, see the Macro Calculator and for tracking calorie deficits, use the Calorie Deficit Calculator.

Scheduling Tips

• Spread restricted days apart (e.g., Tuesday and Thursday for 5:2)
• Avoid placing restricted days on heavy training days
• Stay well-hydrated on restricted days — water, black coffee, and herbal tea contribute zero calories
• Focus on high-volume, low-calorie foods (vegetables, lean protein) to manage satiety on restricted days