How to Build a Cut Protocol That Actually Works

TL;DR: Calculate your TDEE (Mifflin-St Jeor equation x activity multiplier), set a calorie deficit capped at 70% of the Alpert limit (22 kcal/lb of fat mass/day), eat 1g protein per pound of bodyweight, keep fat at 25-30%, fill the rest with carbs. Plan diet breaks every 8-12 weeks. A 20% to 12% body fat cut takes 16-24 weeks. Use our free cut calculator to get your exact numbers.

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Cutting isn't complicated. But most people make it complicated by either going too aggressive (and losing muscle) or too conservative (and spending 6 months spinning their wheels at the same body fat).

Here's how to build a cut protocol grounded in actual physiology.

Step 1: Know Your Numbers

You need three data points before you can set a deficit:

1. Current weight — weigh yourself first thing in the morning, average over 7 days
2. Estimated body fat % — Navy method, DEXA scan, or a calibrated smart scale. Doesn't need to be perfect, but you need a reasonable estimate
3. Maintenance calories (TDEE) — use the Mifflin-St Jeor equation, then multiply by your activity factor

The Mifflin-St Jeor equation:

• Males: (10 × weight_kg) + (6.25 × height_cm) - (5 × age) + 5
• Females: (10 × weight_kg) + (6.25 × height_cm) - (5 × age) - 161

Multiply by your activity level: Sedentary (1.2), Lightly Active (1.375), Moderately Active (1.55), Very Active (1.725).

Don't want to do the math? Use our free cut calculator — plug in your stats and get your deficit, macros, and timeline instantly.

Step 2: Set Your Deficit (The Alpert Limit)

Here's what most "just eat 500 calories less" advice gets wrong: the maximum rate your body can pull energy from fat stores is physiologically capped.

Alpert (2005) established this cap at approximately 22 kcal per pound of fat mass per day. If your deficit exceeds this, the extra energy comes from muscle, not fat. That's the opposite of what you want.

Example: A 180 lb person at 20% body fat has 36 lbs of fat mass. Their maximum sustainable deficit is ~792 cal/day. Going to a 1,200 cal deficit would guarantee muscle loss.

| Body Fat % | Fat Mass (180 lbs) | Max Deficit | Weekly Fat Loss | |------------|-------------------|-------------|-----------------| | 25% | 45 lbs | ~990 cal/day | ~2.0 lbs/wk | | 20% | 36 lbs | ~792 cal/day | ~1.6 lbs/wk | | 15% | 27 lbs | ~594 cal/day | ~1.2 lbs/wk | | 12% | 21.6 lbs | ~475 cal/day | ~0.95 lbs/wk |

The leaner you get, the slower you must go. This isn't optional — it's physics.

Step 3: Set Your Macros

During a cut, protein is the most important macro. It preserves lean mass, keeps you satiated, and has a higher thermic effect than carbs or fat.

Protein: 1.0g per pound of bodyweight. Non-negotiable during a cut. Research consistently shows this is the threshold for maximal muscle preservation in a caloric deficit.

Fat: 25-30% of total calories. Don't go below 20% — you need dietary fat for hormone production (testosterone, estrogen, cortisol regulation).

Carbs: Whatever's left after protein and fat. Carbs fuel your training, so don't zero them out unless you have a specific reason.

Example for a 180 lb person at 2,000 cal/day:

• Protein: 180g (720 cal)
• Fat: 60g (540 cal, ~27%)
• Carbs: 185g (740 cal)

Step 4: Protect Your Muscle

The deficit handles fat loss. Your job is to make sure you don't lose muscle along the way:

1. Keep lifting heavy — maintain the intensity (weight on the bar) even if you reduce volume. The stimulus to maintain muscle is mechanical tension, not pump or volume.
2. High protein — already covered, but it bears repeating. 1g/lb.
3. Don't crash your calories — respect the Alpert limit. Aggressive deficits feel productive but they're eating your muscle.
4. Sleep 7-9 hours — growth hormone peaks during deep sleep. Cutting on poor sleep is a recipe for muscle loss.
5. Manage stress — chronically elevated cortisol promotes muscle catabolism and fat retention. Counterproductive.

Step 5: Set a Realistic Timeline

Most people underestimate how long a proper cut takes. Here's a realistic framework:

• 25% → 15% body fat: 16-24 weeks
• 20% → 12% body fat: 16-24 weeks
• 15% → 10% body fat: 12-20 weeks (gets progressively slower)

These ranges account for the diminishing deficit as you get leaner (per the Alpert limit) and include 1-2 diet breaks.

Step 6: Plan Diet Breaks

Every 8-12 weeks of sustained deficit, spend 1-2 weeks eating at maintenance. This:

• Restores leptin and ghrelin to pre-cut levels
• Gives your nervous system a break from NEAT suppression
• Provides a psychological reset
• Does NOT erase your progress — you'll gain 2-3 lbs of water/glycogen that drops off within a week of resuming the deficit

The Protocol, Summarized

1. Calculate TDEE with Mifflin-St Jeor
2. Set deficit at 70% of your Alpert limit (moderate pace)
3. Protein at 1g/lb, fat at 25-30%, carbs fill the rest
4. Maintain training intensity, consider reducing volume 10-20%
5. Diet break every 8-12 weeks
6. Track weekly weight averages and body measurements, not daily scale

The math is straightforward. The execution is where people struggle. Having a system that tracks it all and shows you the projected timeline — that's the difference between finishing a cut and quitting at week 4.

Try our free cut calculator to get your personalized numbers, or download Protokl for the full protocol with daily tracking, forecasting, and auto-adjusted nutrition targets.