Calorie cycling (sometimes called zigzag dieting) is a structured nutrition strategy where you eat a different number of calories each day of the week — higher on training days, lower on rest days — while keeping the seven-day total fixed at the amount needed to achieve your body-composition goal. The idea is that your body actually needs more fuel on the days you stress it with exercise, and less when you are sedentary. Matching intake to demand improves workout performance, aids recovery, and — for many people — makes the overall diet easier to stick to because you are never eating the same small number every single day.
This calculator takes your biometrics, your baseline activity level, and your weekly goal (fat loss, maintenance, or lean bulk), then lets you label each day of the week as a Training, Active, Light, or Rest day. It works out the mathematically correct calorie target for each day so that the seven values sum to exactly your weekly calorie envelope.
How it works
Step 1 — Estimate BMR using Mifflin-St Jeor (1990):
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (men) BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161 (women)
Step 2 — Multiply by an activity factor to get TDEE:
Activity factors range from 1.2 (sedentary) to 1.9 (very active). This gives your Total Daily Energy Expenditure — the flat daily intake that would keep your weight stable if you ate the same amount every day.
Step 3 — Set your weekly calorie target:
Weekly target = 7 × TDEE + weekly goal adjustment
One kilogram of body fat stores roughly 7,700 kcal, so losing 0.5 kg/week requires a weekly deficit of 3,850 kcal; gaining 0.5 kg/week (lean bulk) requires a weekly surplus of 3,850 kcal.
Step 4 — Distribute across days using proportional weighting:
Each day type has a relative multiplier:
| Day type | Multiplier |
|---|---|
| Training (High) | 1.2 |
| Active (Medium) | 1.0 |
| Light (Low) | 0.8 |
| Rest (Very Low) | 0.6 |
Day calories = (day multiplier ÷ sum of all 7 multipliers) × weekly target
This normalisation means the exact split changes with your schedule — three hard training days and four rest days produces a wider swing than a mixed week.
Worked example
A 28-year-old woman, 165 cm, 68 kg, lightly active, aiming to lose 0.5 kg/week:
- BMR = 10 × 68 + 6.25 × 165 − 5 × 28 − 161 = 1,430 kcal
- TDEE = 1,430 × 1.375 = 1,966 kcal/day
- Weekly target = 7 × 1,966 − 3,850 = 9,912 kcal
Default 3 High + 2 Medium + 1 Low + 1 Rest schedule (sum of multipliers = 3×1.2 + 2×1.0 + 1×0.8 + 1×0.6 = 7.0):
| Day | Type | Calories |
|---|---|---|
| Mon | Training | (1.2 ÷ 7.0) × 9,912 = 1,699 kcal |
| Tue | Active | (1.0 ÷ 7.0) × 9,912 = 1,416 kcal |
| Wed | Training | 1,699 kcal |
| Thu | Active | 1,416 kcal |
| Fri | Training | 1,699 kcal |
| Sat | Light | (0.8 ÷ 7.0) × 9,912 = 1,133 kcal |
| Sun | Rest | (0.6 ÷ 7.0) × 9,912 = 849 kcal |
| Total | 9,911 kcal (rounds to target) |
The average is 1,416 kcal/day — identical to a flat deficit of the same size — but training days are fuelled properly and the weekly target is met.
All calculations run entirely in your browser. Nothing is uploaded or stored.