Fat Loss Formula

Macro Cycling Formula

Macro cycling matches daily carbohydrate intake to daily training demand. Hard training days get higher carbs (6-10 g/kg); easy or rest days get fewer (3-4 g/kg). Protein stays constant at 1.6-2.2 g/kg every day. Fat fills the remainder. Burke & Hawley 2018 framework reflects glycogen recovery research — chronic over-feeding carbs on rest days adds calories without benefit; under-feeding carbs on training days impairs session quality.

4 VARIABLESPublished May 14, 2026Live Content

By AI Fit Hub · AI Fit Hub Team

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Formula 4 variables Worked example Variations

Education · Not medical advice. Output is deterministic math from your inputs.Editorial standards Sponsor disclosure Corrections

Formula

Copy the exact expression or work through it step by step below.

 carb_g_training = mass_kg × (6 to 10) g/kg
carb_g_rest    = mass_kg × (3 to 4) g/kg
protein_g       = mass_kg × (1.6 to 2.2) g/kg   [constant across days]
fat_g           = remaining calories / 9   [fat is the slack]

Variables

carb_g_training

Training-day carbs

Higher dose to fuel session glycogen needs + replace post-session loss. Range: 6 g/kg (moderate training) to 10 g/kg (multi-hour endurance days).

carb_g_rest

Rest-day carbs

Lower dose since metabolic demand is lower. Range: 3 g/kg (sedentary rest) to 4 g/kg (active recovery — walking, mobility work, easy spin).

protein_g

Protein (constant)

ISSN 2017 evidence-based range: 1.6-2.2 g/kg/day. Higher end (2.0-2.2) during fat-loss phases or for strength athletes; 1.6 for general fitness. Keep CONSTANT across training and rest days — protein protects against muscle loss most effectively when daily.

fat_g

Fat (remainder)

After protein + carbs, fat fills the remaining calories. Floor at 0.8 g/kg for hormone health (testosterone, ghrelin/leptin signaling). On hard-training days fat tends to be lower; on rest days higher.

Step By Step

1

Identify your training schedule. Categorize each day: hard training, moderate, easy/rest.

Week: Mon hard lift, Tue easy run, Wed hard lift, Thu rest, Fri hard lift, Sat moderate cardio, Sun rest. So 3 hard days, 1 moderate, 1 easy, 2 rest.
2

Set protein target. Same every day.

80 kg × 2.0 g/kg = 160 g protein/day (every day).
3

Set hard-day carb target: 6-10 g/kg based on duration/intensity.

Hard lift (60-90 min): 6 g/kg → 80 × 6 = 480 g carbs.
4

Set rest-day carb target: 3-4 g/kg.

Full rest: 3 g/kg → 80 × 3 = 240 g carbs. Easy run day: 4 g/kg = 320 g.
5

Fill remaining calories with fat. Compute total calories per day type from TDEE.

Hard lift day: 160 × 4 + 480 × 4 = 640 + 1,920 = 2,560 from P+C. TDEE 2,800. Remaining: 240 cal → 27 g fat. Rest day: 160 × 4 + 240 × 4 = 1,600 from P+C. TDEE 2,300 (no exercise). Remaining: 700 cal → 78 g fat. Compare: hard-day low fat + carb-loaded; rest-day higher fat.

Worked Example

80 kg recreational lifter, 3 hard sessions/week + 1 moderate + 1 easy + 2 rest, maintenance kcal cycle

Body mass

80 kg

TDEE hard day

2,800 kcal

TDEE rest day

2,300 kcal

Protein constant

2.0 g/kg = 160 g/day

Hard day: 160P / 480C / 27F (kcal 640+1920+243 = 2,803) Mod day (4 g/kg C): 160P / 320C / 47F (kcal 640+1280+423 = 2,343) Rest day: 160P / 240C / 78F (kcal 640+960+700 = 2,300) Weekly avg: (3×2,803 + 1×2,500 + 1×2,343 + 2×2,300) / 7 = 2,535 kcal/day

Weekly average maintenance with daily variance. Total weekly carbs: 3,200 g (vs 4,200 g if 480 carbs every day). Saved ~1,000 g carbs/week = ~4,000 fewer kcal across the week. Allows a slight surplus on hard days (supporting recovery + training quality) without exceeding weekly maintenance.

Common Variations

Train-low / sleep-low (Burke 2017): occasional sessions performed with low glycogen to trigger mitochondrial adaptation. 2-3 sessions/week max. Performance during the low-glycogen session is impaired; adaptation upside is the benefit.

Refeed / diet break (Helms 2014, MATADOR trial Byrne 2018): planned 1-2 week refeed every 4-6 weeks of dieting to restore leptin/thyroid signaling. Carbs spike to 5-6 g/kg, calories at maintenance.

Carb back-loading (Kiefer): 80% of daily carbs concentrated post-training. Not well-supported empirically — total daily carbs matters more than timing for most outcomes (Aragon & Schoenfeld 2013).

Targeted ketogenic (cyclical keto): 5-6 days ketogenic + 1-2 days high-carb. Research thin; popular among physique competitors who already have lower carb tolerance.

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FAQ

Questions people ask next

The short answers readers usually want after the first pass.

What is macro cycling and how does it work?

Macro cycling matches daily carbohydrate intake to daily training demand: hard training days get higher carbs (6-10 g/kg) and easy or rest days get fewer (3-4 g/kg). Protein stays constant at 1.6-2.2 g/kg every day and fat fills the remaining calories. It avoids over-feeding carbs on rest days while still fueling hard sessions.

How many carbs on a rest day versus a training day?

Training days use 6 g/kg for moderate work up to 10 g/kg for multi-hour endurance days, while rest days drop to 3 g/kg for sedentary rest or 4 g/kg for active recovery like walking or an easy spin. For an 80 kg lifter that is about 480 g of carbs on a hard day versus 240 g on a full rest day.

Should protein change on training versus rest days?

No. Protein stays constant at 1.6-2.2 g/kg every day, with the higher end (2.0-2.2) during fat-loss phases or for strength athletes. Daily protein protects against muscle loss most effectively, so it does not get cycled the way carbs do.

Does macro cycling save calories over the week?

Yes, by lowering carbs on easy and rest days. The worked example for an 80 kg lifter totals about 3,200 g of carbs per week versus 4,200 g if you ate 480 g every day, roughly 1,000 g fewer carbs or about 4,000 fewer calories across the week, while still allowing a slight surplus on hard days.

Does carb timing or back-loading matter for macro cycling?

Not much. Carb back-loading (concentrating most daily carbs post-training) is not well supported empirically; total daily carbohydrate matters more than timing for most outcomes. The cycling benefit comes from matching the day's total carbs to that day's training demand, not from when you eat them.

Sources & References

Burke et al. (2018). Toward a common understanding of diet-exercise strategies to manipulate fuel availability for training and competition preparation in endurance sport. — International Journal of Sport Nutrition and Exercise Metabolism — periodized nutrition framework
Burke (2015). Re-examining high-fat diets for sports performance: did we call the 'nail in the coffin' too soon? — Sports Medicine — train-low protocol evidence
Byrne et al. (2018). Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. — International Journal of Obesity — diet break / refeed evidence
Aragon & Schoenfeld (2013). Nutrient timing revisited: is there a post-exercise anabolic window? — JISSN — timing vs total daily intake