Whether you're maintaining, trying to lose fat, building muscle, or fueling an active lifestyle, understanding your macros starts with knowing how much energy your body actually needs. Let me walk you through this step-by-step.
Step 1: Calculate Your BMR (Basal Metabolic Rate)
Your BMR is the number of calories your body needs just to stay alive—breathing, pumping blood, keeping your organs functioning. Think of it as your "doing absolutely nothing all day" number.
We'll use the Mifflin-St Jeor formula (the most accurate for adults):
For Women:
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
For Men:
BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Quick conversions:
- Pounds to kg: divide by 2.2
- Inches to cm: multiply by 2.54
Example (mine):
- Weight: 178 lbs ÷ 2.2 = 81 kg
- Height: 5'3" (63 inches) × 2.54 = 160 cm
- Age: 39
My BMR: (10 × 81) + (6.25 × 160) − (5 × 39) − 161 = 1,454 calories
That's just to keep my body functioning. Now let's add real life.
Step 2: Calculate Your TDEE (Total Daily Energy Expenditure)
Your TDEE accounts for your actual activity level. This is where most people underestimate.
Choose your activity multiplier:
- Sedentary (desk job, minimal movement): × 1.2
- Lightly active (exercise 1-3x/week): × 1.375
- Moderately active (exercise 3-5x/week): × 1.55
- Very active (exercise 6-7x/week): × 1.725
- Athlete/labor job (intense daily activity): × 1.9
My example:
I train for a 10K, strength train 3-5x/week, and have a labor-intensive job. I'm between "very active" and "athlete," so I use 1.75.
My TDEE: 1,454 × 1.75 = 2,555 calories
This is my maintenance! What I need to eat to fuel my activity without gaining or losing weight.
Step 3: Break Down Your Macros
Now we split those calories into protein, fat, and carbs.
Protein: The muscle protector
Active adults need 0.7-1.0g per pound of bodyweight (or goal bodyweight).
For me: 160-180g protein
Let's use 160g for maintenance:
160g × 4 calories/gram = 640 calories from protein
Fat: The hormone helper
Minimum for active people: 0.3g per pound of bodyweight
For me: 180 × 0.3 = 54g fat
54g × 9 calories/gram = 486 calories from fat
Carbs: Your body's premium fuel
After protein and fat, the rest of your calories come from carbs (though you can increase fat if you prefer—just reduce carbs to compensate).
Remaining calories for carbs:
2,555 - (640 + 486) = 1,429 calories
1,429 ÷ 4 calories/gram = 357g carbs
My maintenance macros:
- 160g protein
- 54g fat
- 357g carbs
Yes, that's a lot of carbs. And yes, I need them to fuel my training and not feel like garbage.
Adjusting for Your Goals
Now that you know your maintenance numbers, let's adjust based on what you're trying to achieve.
Goal 1: Fat Loss
Create a moderate deficit of 300-500 calories. Don't go too aggressive or you'll lose muscle, tank your energy, and make yourself miserable.
My fat loss calories:
2,555 - 400 = 2,155 calories
Keep protein HIGH during a cut to preserve muscle:
- Protein: 180g × 4 = 720 cal
- Fat: 54g × 9 = 486 cal (keep at minimum)
- Remaining for carbs: 2,155 - 1,206 = 949 cal
- Carbs: 949 ÷ 4 = 237g
My fat loss macros:
- 180g protein
- 54g fat
- 237g carbs
What to expect: Aim to lose 0.5-1% of your bodyweight per week. Slower is better for preserving muscle.
Goal 2: Muscle Gain
Building muscle requires a calorie surplus—you need to eat more than your TDEE. But here's the key: go slow and steady or you'll just gain unnecessary fat.
Aim for a surplus of 200-300 calories (maybe 400-500 if you're a hard gainer who struggles to put on weight).
My muscle gain calories:
2,555 + 300 = 2,855 calories
Keep protein high for muscle building:
- Protein: 180g × 4 = 720 cal
- Fat: 65g × 9 = 585 cal (slightly higher for hormone production)
- Remaining for carbs: 2,855 - 1,305 = 1,550 cal
- Carbs: 1,550 ÷ 4 = 388g
My muscle gain macros:
- 180g protein
- 65g fat
- 388g carbs
What to expect: Aim to gain 0.5-1 lb per week max (2-4 lbs per month). If you're gaining faster, you're probably adding too much fat.
Quick Comparison: All Three Goals Side-by-Side
Here's how my macros look across all three goals:
Goal Calories Protein Fat Carbs
Maintenance 2,555 160g 54g 357g
Fat Loss 2,155 180g 54g 237g
Muscle Gain 2,855 180g 65g 388g
Notice the patterns:
- Protein stays high or increases (never decreases)
- Fat stays at minimum for fat loss, slightly higher for muscle gain
- Carbs are the main variable that adjusts with your calorie needs
- The calorie differences are moderate (200-400 calories), not extreme
- Also, this is how I play with the numbers to see what I can do and what I can't do. I've never eaten over 250g of carbs and I'm used to doing low carb. THESE ARE NOT SET IN STONE NUMBERS! Use them as a guide.
The Formula Cheat Sheet
Step 1: Calculate BMR
- Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161
- Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
Step 2: Calculate TDEE
- BMR × activity factor
Step 3: Adjust for your goal
- Maintenance: TDEE
- Fat loss: TDEE - 300-500
- Muscle gain: TDEE + 200-300
Step 4: Set macros
Maintenance:
- Protein: 0.7-1.0g per lb bodyweight
- Fat: 0.3g per lb (minimum)
- Carbs: Remaining calories ÷ 4
Fat Loss:
- Protein: 1.0g per lb bodyweight (or higher)
- Fat: 0.3g per lb (minimum)
- Carbs: Remaining calories ÷ 4
Muscle Gain:
- Protein: 0.8-1.0g per lb bodyweight
- Fat: 0.35-0.4g per lb
- Carbs: Remaining calories ÷ 4
Tips for Success (No Matter Your Goal)
Track consistently for 2-3 weeks before making changes. Your body needs time to show you what's working.
Adjust based on results:
- Fat loss: Losing more than 1% bodyweight per week? Add 100-200 calories. Not losing after 3 weeks? Reduce by 100-200 calories.
- Muscle gain: Gaining more than 1 lb per week? Reduce by 100-200 calories. Not gaining after 3 weeks? Add 100-200 calories.
- Feeling exhausted? You might be under-eating—especially carbs.
Don't fear carbs. They fuel your workouts, support your thyroid, help you sleep, and keep your brain functioning. If you're active, you NEED them.
These are minimums. Especially for fat and protein. You can eat more fat if you prefer (some people feel better with higher fat)—just reduce carbs to keep your total calories in check.
Protein is non-negotiable. Whether you're cutting, maintaining, or bulking, high protein supports your goals. Don't skimp here.
Be patient. Fat loss and muscle gain are both slow processes. Trust the process and give it time.
Your Turn
Grab a calculator (or your phone) and run your numbers:
- What's your BMR?
- What's your activity level?
- What's your TDEE?
- What's your goal?
- What are your macros?
Drop your numbers in the comments—I'd love to see them!
And remember: food is fuel, not the enemy. Eat to support your goals, your energy, and your life.
Want help? Questions about your specific situation? Comment below or DM me. Let's figure this out together.
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