Cutting 101: How to Lose Fat

You've spent months building muscle. Now you want to see it. Cutting — a structured period of fat loss — is how you reveal the physique underneath. But done wrong, you'll lose muscle, tank your performance, and end up worse than where you started. This guide covers everything you need to cut effectively while keeping the muscle you worked hard to build.

What Is a Cut?

A cut is a planned period of calorie restriction designed to lose body fat while preserving as much muscle mass as possible. Unlike casual "dieting," cutting is a deliberate, time-limited phase with clear targets for calorie intake, macronutrients, and training adjustments.

When to cut:

• You can't see muscle definition despite consistent training
• Your body fat percentage is above your target for aesthetics or performance
• You've completed a sufficient building phase (at least 3-6 months)

When NOT to cut:

• You haven't built enough muscle to reveal anything
• You're already lean (sub-12% for men, sub-20% for women)
• You're in the middle of a strength peaking cycle
• You're chronically stressed, sleep-deprived, or recovering from illness

Setting Up Your Calorie Deficit

Fat loss requires one thing: consuming fewer calories than you burn. Everything else — meal timing, food choices, supplements — is secondary to this energy balance.

Step 1: Estimate Your Maintenance Calories

Your Total Daily Energy Expenditure (TDEE) is the number of calories you burn per day:

TDEE = BMR × Activity Multiplier

For BMR, the Mifflin-St Jeor equation is the most validated for most people:

• Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
• Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

Step 2: Set Your Deficit

Research by Helms et al. (2014) recommends a rate of weight loss of approximately 0.5-1% of bodyweight per week to maximize muscle retention during a cut. This was further supported by Garthe et al. (2011), who found that athletes losing weight at a slower rate (~0.7% BW/week) actually gained lean body mass (+2.1%), while those cutting faster (~1.4% BW/week) did not.

In practice:

Iridium's macro and calorie goal setup includes a built-in TDEE calculator based on your profile and activity level. Set your goal to "Lose," choose your target weekly rate, and it calculates the appropriate calorie target — no manual math required.

Macros During a Cut

Not all calories are equal when you're trying to preserve muscle. How you distribute your macronutrients matters.

Protein: The Non-Negotiable

Protein is the most critical macro during a cut. A systematic review by Helms et al. (2014) concluded that resistance-trained athletes in a calorie deficit should consume 2.3-3.1 g/kg of fat-free mass per day, with protein needs scaling upward as the deficit becomes more severe and body fat decreases.

For a practical starting point, most lifters should aim for approximately 1.0 g per pound of bodyweight (2.2 g/kg total bodyweight), which falls comfortably within the evidence-based range for most body compositions.

A meta-analysis by Morton et al. (2018) confirmed that total daily protein intake is the primary driver of muscle preservation, with benefits plateauing around 1.6 g/kg/day in calorie surplus — but deficit conditions warrant the higher end of the range.

Fat: Don't Go Too Low

Dietary fat supports hormone production (including testosterone), vitamin absorption, and satiety. Don't drop below 0.3 g per pound of bodyweight (~0.7 g/kg).

A reasonable fat target during a cut: 25-35% of total calories.

Carbs: Fill the Rest

After setting protein and fat, your remaining calories go to carbohydrates. Carbs fuel training performance and recovery — don't restrict them unnecessarily.

How to Train During a Cut

This is where most people mess up. They either switch to high-rep "toning" workouts, pile on excessive volume, or stop training heavy entirely. All three are wrong.

The Priority: Maintain Intensity

Your number one training goal during a cut is to maintain the weight on the bar. This is the strongest signal to your body to keep muscle. If you were squatting 275 for 5 before the cut, fight to keep squatting 275 for 5.

Volume Adjustments

You probably can't sustain your bulking volume on reduced calories. That's fine. You can reduce volume by 20-30% and still maintain muscle as long as intensity stays high.

If you're using volume landmarks to guide your training, aim to train at or slightly above your MEV (Minimum Effective Volume) during a cut. You don't need MAV or MRV levels — you just need enough stimulus to tell your body "keep this muscle."

What to Change (and What to Keep)

Cardio: Types and How Much

Cardio is a tool for increasing your calorie deficit — nothing more. It's not required for fat loss, but it helps when you don't want to drop food intake further.

HIIT vs. Steady-State

A meta-analysis by Wewege et al. (2017) found no significant difference between HIIT and moderate-intensity continuous training for fat loss outcomes. Both work. The main advantage of HIIT is time efficiency — comparable results in approximately 40% less training time.

How Much Cardio?

Start with less than you think you need. You can always add more.

• Weeks 1-4: 2-3 sessions of LISS (20-30 min) or 1-2 HIIT sessions
• Weeks 5-8: Increase if weight loss stalls — add a session or extend duration
• Weeks 9+: Adjust as needed, but avoid exceeding 5-6 total cardio sessions per week

Managing Metabolic Adaptation

Your body doesn't want to lose weight. As you diet, metabolic adaptations kick in to resist the deficit. Trexler et al. (2014) reviewed these adaptations in athletes, which include:

• Decreased resting metabolic rate beyond what's explained by lost body mass
• Hormonal shifts — reduced thyroid output, lower testosterone, increased cortisol
• Increased hunger signals — ghrelin rises, leptin drops
• Reduced non-exercise activity (NEAT) — you move less without realizing it

How to Combat Metabolic Adaptation

1. Diet breaks — Every 4-6 weeks, spend 1-2 weeks eating at maintenance calories. This partially reverses metabolic adaptation and gives you a psychological reset.
2. Refeed days — 1-2 days per week at maintenance, primarily from extra carbs. Helps restore glycogen and can temporarily improve hormonal markers.
3. Don't crash diet — Aggressive deficits accelerate metabolic adaptation. The moderate approach outlined above minimizes this.
4. Keep NEAT high — Aim for 8,000-10,000 daily steps. When your body reduces spontaneous movement, consciously fight it.

Protecting Muscle During Fat Loss

Everything above contributes to muscle preservation. Here's the hierarchy of importance:

1. Sufficient protein — 2.2 g/kg bodyweight (or 2.3-3.1 g/kg fat-free mass)
2. Resistance training — Maintain intensity; don't switch to "light weight, high reps"
3. Moderate deficit — 0.5-1% bodyweight loss per week, not more
4. Adequate sleep — 7-9 hours. Sleep deprivation accelerates muscle loss during a deficit.
5. Stress management — Elevated cortisol promotes muscle breakdown

The single most important thing during a cut is showing up and training heavy. Everything else is optimization.

Iridium's recovery tracking becomes especially valuable during a cut. Your readiness score factors in sleep, HRV, muscle fatigue, and training load — all of which shift rapidly when you're in a deficit. Use it to make informed decisions about when to push and when to pull back.

Realistic Timelines

Cutting takes longer than most people want. Here are realistic expectations for a 180 lb male:

After the Cut

Don't immediately jump back to surplus calories. Spend 2-4 weeks at maintenance (a reverse diet) to:

• Stabilize your new body weight
• Allow hormones to normalize
• Restore training performance
• Prevent rapid fat regain

Start Your Cut

Fat loss is straightforward but not easy. Set a moderate deficit, keep protein high, train hard, add cardio strategically, and give it time. The science is clear on what works — the challenge is execution and consistency.

Download Iridium to set up your cutting macros with the built-in calorie and goal wizard, track your nutrition with 9 different logging methods including photo AI and barcode scanning, and get AI-generated workouts that adapt to your recovery status — so you can cut smarter, not harder.