How to Adjust Macros When Cutting vs Bulking

Adjusting your diet from building muscle to losing fat feels complicated. You've heard the terms, but the numbers are a mess. This guide explains exactly how to adjust macros when cutting vs bulking using simple math, so you can stop guessing and start seeing predictable results.

Key Takeaways

• Your protein intake is the anchor. Keep it constant at 0.8-1.0 grams per pound of your target body weight for both cutting and bulking.
• Calories drive the change. For cutting, create a 300-500 calorie deficit. For bulking, create a 300-500 calorie surplus.
• Carbs and fats are the levers you pull. To cut, you will primarily reduce carbohydrates. To bulk, you will primarily increase carbohydrates.
• Fat intake has a floor. Do not let your fat drop below 0.3 grams per pound of body weight, as it's essential for hormone function.
• The only significant change between a cut and a bulk is your total calories, which is managed by adjusting your carb and fat intake, not your protein.

The One Macro That Never Changes: Protein

If you're confused about how to adjust macros when cutting vs bulking, start here. Protein is the single most important macronutrient, and it's the one you should change the least.

Think of protein as the foundation of your house. Whether you're renovating (cutting) or adding an extension (bulking), you don't touch the foundation. You need it to hold everything up.

During a cut, a high-protein diet (along with resistance training) tells your body to burn fat for energy while preserving your hard-earned muscle. Without enough protein, your body will break down muscle tissue for fuel, leaving you looking "skinny-fat," not lean.

During a bulk, protein provides the literal building blocks for new muscle tissue. You can't build a brick wall without bricks.

The Golden Rule: 0.8 to 1.0 Grams Per Pound

For both cutting and bulking, aim for 0.8 to 1.0 grams of protein per pound of your *goal* body weight. If you are significantly overweight, use your target body weight to avoid over-calculating.

Let's use a 180-pound person as an example:

• Protein Goal: 180 lbs x 1.0g/lb = 180 grams of protein per day.

This number stays the same whether you are trying to lose 10 pounds or gain 5 pounds. It's your anchor. Don't overcomplicate it. Hit this number every single day. One gram of protein has 4 calories.

So, for our 180-pound person, their protein intake accounts for:

• 180g protein x 4 calories/gram = 720 calories.

This 720 calories from protein is your constant. Now we just need to figure out the rest.

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Calories: The Engine for Cutting and Bulking

With protein locked in, the next step is setting your total calories. This is the engine that determines whether your body's weight goes up or down. Everything hinges on this number.

First, you need a baseline: your maintenance calories. This is the number of calories you need to eat per day to keep your weight exactly the same. You can get a rough estimate by multiplying your body weight in pounds by 14-16.

• Quick Maintenance Estimate: Bodyweight (lbs) x 15

For our 180-pound person:

• 180 lbs x 15 = 2,700 calories (This is their estimated maintenance).

This is just a starting point. The real number will depend on your activity level, age, and metabolism. But it's close enough to get started.

The Calorie Math for Cutting

To lose fat, you need to be in a calorie deficit. This means consuming fewer calories than your body burns. A smart, sustainable deficit is 300-500 calories below your maintenance.

• Cutting Calories: Maintenance - 500 calories
• Example: 2,700 (maintenance) - 500 = 2,200 calories per day for cutting.

A 500-calorie daily deficit will lead to approximately 1 pound of fat loss per week (3,500 calories = 1 pound of fat). Going lower than this risks significant muscle loss and metabolic slowdown.

The Calorie Math for Bulking

To build muscle, you need to be in a calorie surplus. This provides the extra energy required for muscle repair and growth. A clean, effective surplus is 300-500 calories above your maintenance.

• Bulking Calories: Maintenance + 300 calories
• Example: 2,700 (maintenance) + 300 = 3,000 calories per day for bulking.

Starting with a smaller surplus of 300 calories helps ensure most of the weight you gain is muscle, not fat. If you're not gaining weight after 2-3 weeks, you can increase it to 500.

How to Adjust Carbs and Fats (The Step-by-Step Math)

This is where it all comes together. You have your protein goal and your total calorie targets for cutting and bulking. Now you just need to fill in the remaining calories with carbohydrates and fats.

Remember these values:

• Protein: 4 calories per gram
• Carbohydrates: 4 calories per gram
• Fat: 9 calories per gram

Step 1: Set Your Protein Intake

As we established, this is your constant. For our 180-pound person, it's 180 grams of protein, which is 720 calories.

Step 2: Set Your Fat Intake

Fat is crucial for hormone production, including testosterone. Don't cut it too low. A safe minimum is 0.3 grams per pound of body weight. A good general range is 20-30% of your total calories.

Let's use 25% of total calories for our example.

For Cutting (2,200 calories):

• Fat Calories: 2,200 x 0.25 = 550 calories
• Fat Grams: 550 calories / 9 cal/gram = ~61 grams of fat

For Bulking (3,000 calories):

• Fat Calories: 3,000 x 0.25 = 750 calories
• Fat Grams: 750 calories / 9 cal/gram = ~83 grams of fat

Step 3: Fill the Rest with Carbs

This is the final piece. Carbs are your body's primary fuel source for high-intensity workouts. You'll simply allocate all remaining calories to carbs.

Putting It All Together: The Cutting Macros

Our 180lb person is cutting on 2,200 calories.

1. Protein: 180g (720 calories)
2. Fat: 61g (550 calories)
3. Calories Used: 720 + 550 = 1,270 calories
4. Calories Remaining for Carbs: 2,200 - 1,270 = 930 calories
5. Carb Grams: 930 calories / 4 cal/gram = ~232 grams of carbs

Final Cutting Macros: 180g Protein / 232g Carbs / 61g Fat

Putting It All Together: The Bulking Macros

Our 180lb person is bulking on 3,000 calories.

1. Protein: 180g (720 calories)
2. Fat: 83g (750 calories)
3. Calories Used: 720 + 750 = 1,470 calories
4. Calories Remaining for Carbs: 3,000 - 1,470 = 1,530 calories
5. Carb Grams: 1,530 calories / 4 cal/gram = ~382 grams of carbs

Final Bulking Macros: 180g Protein / 382g Carbs / 83g Fat

Notice the only things that changed were the carbs and fats. Protein stayed the same. This is the entire secret.

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What to Expect and When to Readjust

Your body is a dynamic system, not a static equation. These numbers are your starting point, not the final word. You must track your progress and adjust based on real-world feedback.

If You're Cutting:

• Goal: Lose 0.5-1% of your body weight per week.
• For a 180lb person, this is 0.9 to 1.8 pounds per week.
• If you're losing weight faster than this: You're likely losing muscle. Increase your calories by 100-150 (add about 25-35g of carbs).
• If you're not losing weight (after 2 weeks): Your maintenance estimate was too high. Decrease your calories by another 100-150 (remove 25-35g of carbs).

If You're Bulking:

• Goal: Gain 0.5-1% of your body weight per *month*.
• For a 180lb person, this is 0.9 to 1.8 pounds per month.
• If you're gaining weight faster than this: You're likely gaining excess fat. Decrease your calories by 100-150 (remove 25-35g of carbs).
• If you're not gaining weight (after 2 weeks): Your maintenance estimate was too low. Increase your calories by 100-150 (add 25-35g of carbs).

Weigh yourself daily, but only pay attention to the weekly average. Your weight will fluctuate daily due to water, salt, and food volume. Look at the trend over 2-3 weeks before making any changes.

Recalculate your maintenance calories and macros every time you gain or lose 10-15 pounds, as your body's energy needs will have changed.

Frequently Asked Questions

Should I use an online macro calculator?

Online calculators are a great starting point to get a rough estimate of your maintenance calories. However, they are just estimates. Use one to get your initial numbers, but then follow the adjustment protocol in this guide based on your actual weight change. This guide teaches you the logic so you can be in control.

Does the carb/fat split matter that much?

Total calories and protein intake are responsible for about 90% of your results. The exact split between carbs and fats is less critical. However, keeping fat above 0.3g/lb is important for health, and prioritizing carbs helps fuel your workouts. The method outlined here provides a balanced and effective starting point.

How do I know if I'm gaining fat instead of muscle on a bulk?

Track your waist measurement along with your body weight. If your waist is growing at the same rate or faster than your chest and shoulders, you're likely gaining too much fat. Also, if you're gaining much more than 1% of your body weight per month, it's almost certainly not all muscle.

What if I hit a weight loss plateau when cutting?

Plateaus are a normal part of fat loss. Your body has adapted to the lower calorie intake. You have two options: slightly decrease your calories again (by 100-150) or increase your energy expenditure. Adding 2,000-3,000 steps to your daily routine is often enough to break through a plateau without having to eat less.

Conclusion

Switching between cutting and bulking isn't about a complete dietary overhaul. It's a simple, calculated adjustment.

Anchor your diet with consistent, high protein. Then, simply turn the calorie dial up or down using carbs and fats to match your goal. You now have the complete blueprint to do it effectively.