TDEE & Macros: Cut or Bulk With Real Numbers

Meet the Numbers: BMR, Then TDEE

Everything starts with two numbers.

BMR (Basal Metabolic Rate) is what your body burns just keeping you alive — brain running, heart beating, body temperature held. No movement at all. It's the baseline, roughly 60–70% of your daily burn.

TDEE (Total Daily Energy Expenditure) is BMR plus everything else: walking, fidgeting, exercise, digesting food. TDEE is the number that matters for your diet, because eating below it means losing weight and eating above it means gaining.

There are a few formulas for BMR. The Mifflin-St Jeor equation is the one most dietitians reach for:

• 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

Then you multiply by an activity multiplier:

• Sedentary (desk job, little exercise): BMR × 1.2
• Lightly active (light exercise 1–3 days/week): BMR × 1.375
• Moderately active (3–5 days/week): BMR × 1.55
• Very active (hard exercise 6–7 days/week): BMR × 1.725
• Extremely active (physical job or twice-a-day training): BMR × 1.9

Honestly, most people overestimate their activity. The office worker who lifts three times a week is "lightly to moderately active," not very active. Picking too high a multiplier is the most common way people calculate a TDEE that silently sabotages them.

Meet Alex: 80kg, 180cm, 30, Lifting 4x a Week

Let's stop talking in abstracts. Alex is 80kg, 180cm tall, 30 years old, male, works a desk job, and lifts weights four evenings a week. We'll follow him through two scenarios: cutting body fat, then bulking muscle.

First, his BMR using Mifflin-St Jeor:

(10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day

Alex lifts regularly but sits all day, so moderately active is the honest pick: 1,780 × 1.55 = 2,759, which we'll round to 2,760 kcal/day TDEE.

That's the anchor. Everything below hangs off this number. If Alex eats 2,760 a day, his weight roughly holds. Less and he loses. More and he gains. Run your own numbers with the TDEE & Macro Nutrient Split Calculator (US lbs & UK stone) — it does this arithmetic in seconds, including the macro splits coming up.

Scenario 1: Alex Cuts — The 500-Calorie Deficit

A kilogram of body fat stores roughly 7,700 kcal. So to lose about 0.5kg a week — the sweet spot where most people lose mostly fat, not muscle — you need a daily deficit of about 500 kcal.

Alex's cut target: 2,760 − 500 = 2,260 kcal/day.

Now the macros. Protein is the one that matters most on a cut — it protects muscle while you're in a deficit, and it's the most satiating macro. The evidence-based range for active people losing weight is 1.6–2.2g per kilogram of bodyweight. Alex takes the upper end to protect his muscle: 2.0 × 80 = 160g protein/day. Protein has 4 kcal per gram, so that's 640 kcal.

Fat comes next: roughly 0.8–1g per kg is enough to keep hormones healthy. Alex takes 0.9 × 80 = 72g fat. Fat has 9 kcal per gram: 648 kcal.

Carbs get whatever's left: 2,260 − 640 − 648 = 972 kcal, at 4 kcal per gram = 243g carbs.

Alex's cut, final numbers:

• 2,260 kcal/day — protein 160g, fat 72g, carbs 243g
• Expected loss: ~0.5kg/week, so 6kg in about 12 weeks

A few practical notes on cutting. First, protein timing doesn't matter much — daily total beats the "30-minute window" myth. Second, the deficit is a weekly average: a 700-calorie deficit six days and a maintenance day still works. Third, weighing food for two weeks teaches you portion sizes permanently; most people underestimate intake by 20–30% when they guess.

Scenario 2: Alex Bulks — The Modest Surplus

Six months later Alex has leaned out and wants to add muscle. Bulking uses the same TDEE but adds a small surplus: 250–300 kcal/day above maintenance. That's the "lean bulk" zone — enough to build muscle, small enough that most of the gain isn't fat.

Alex's bulk target: 2,760 + 300 = 3,060 kcal/day.

Protein on a bulk can sit at the lower end of the range, since the surplus itself is muscle-sparing: 1.8 × 80 = 144g protein (576 kcal). Fat: 1 × 80 = 80g (720 kcal). Carbs get the rest: 3,060 − 576 − 720 = 1,764 kcal = 441g carbs.

Alex's bulk, final numbers:

• 3,060 kcal/day — protein 144g, fat 80g, carbs 441g
• Expected gain: ~0.25–0.3kg/week, roughly 3kg in 12 weeks

Why not a 1,000-calorie surplus for faster gains? Because past a modest surplus, extra calories don't build extra muscle — studies consistently show the surplus mostly becomes fat. The old "dreamer bulk" just means a longer cut later. Slow bulks look boring and work.

The Protein Reality Check

Notice something: Alex's protein target barely changes between cutting (160g) and bulking (144g). The calories swing by 800; protein barely moves. This is the point most people miss.

Protein is a target — hit it daily. Fat is a floor — don't go below the hormone-healthy minimum, but going over slightly is fine. Carbs are a lever — the flexible calories that fill whatever's left. When someone asks "what should my macros be," the useful answer is mostly the protein number.

For reference, 160g of protein looks like this in food: 200g chicken breast (~62g), a protein shake (~30g), 200g Greek yogurt (~20g), 3 eggs (~18g), 150g salmon (~30g). It takes some planning at first. After a month it's automatic.

Vegetarians and vegans: you can hit these numbers, it just takes more volume. Lentils, tofu, tempeh, seitan, and protein powder are the workhorses. Combine sources through the day (rice + beans, etc.) for complete amino acid profiles — you don't need to combine them in a single meal, despite the old myth.

The 4-Week Feedback Loop

Numbers are starting points, not laws. Activity multipliers are guesses. Your real TDEE reveals itself through data. Here's the loop:

1. Weigh yourself 3–4 mornings a week, same conditions, and take the weekly average. Daily weight bounces 1–2kg from water, glycogen, and salt — the average is the signal. 2. Eat at your target for 4 weeks while keeping training roughly constant. 3. Compare: cutting and losing less than 0.3kg/week? Drop 150–200 kcal. Losing more than 0.8kg/week (and not very overweight)? Add 150. Bulking and gaining nothing after a month? Add 200.

This loop is the difference between people who succeed and people who recalculate TDEE forever. One month of honest data beats any formula. Adjust once, commit, and let the trend do the talking.

Also: recalculate when your weight changes significantly. A 70kg Alex has a different TDEE than an 80kg Alex — every 10kg is roughly 100–150 kcal/day of difference. Revisit the numbers quarterly, not weekly.

Mistakes That Wreck Good Numbers

• The weekend eraser. Five days at 2,260 kcal, then 4,500 kcal on Saturday and Sunday. Weekly average: 2,860 — above maintenance. The whole cut, undone in 48 hours. Track weekends or at least keep them near maintenance.
• Drinking calories. Two large lattes and a beer is 600+ kcal that satisfies nothing. On a cut, liquid calories are the easiest thing to delete.
• The activity lie. "I work out, so I'm very active." Unless you're training twice a day or on your feet all day, you're probably one level lower than you think. Start conservative; adjust up with data.
• Refeed-day mythology. Planned high-carb days have modest evidence for leptin and adherence benefits, but most people use them as an excuse for a cheat day that wipes the deficit. If dieting is going fine without them, skip them.
• Chasing perfect macros daily. Hitting within 10% of each macro, averaged over the week, is indistinguishable from perfection. The person who eats 155g instead of 160g of protein but does it for a year beats the person who hits 160g exactly for three weeks and quits.

Try This Now

Weigh yourself three mornings this week and write down the average. Then plug your stats into the TDEE & Macro Nutrient Split Calculator (US lbs & UK stone) and get your calorie and macro targets. Don't change anything about your diet yet — just observe for a week how far your current eating is from the numbers. That gap is your plan.