Is 40/30/30 a good macro ratio for fat loss?

It's close. This method lands at about 42% protein, 28% fat and 30% carbs for a 200 lb man (200g protein, 60g fat, 140g carbs at 1,900 calories). Set grams per pound instead of percentages, because a percentage split shrinks your protein every time you cut calories.

Do macros matter for weight loss, or just calories?

Calories decide how much weight you lose. Protein decides how much of it is fat instead of muscle. Past that, the carb-to-fat split matters little: in the 12-month DIETFITS trial, low-fat and low-carb groups lost 5.3 and 6.0 kg, a difference that wasn't significant.

What should my macros be to lose fat and build muscle?

Keep protein at 1g per pound, but run a smaller deficit, about 300 calories under maintenance instead of 500. That works best for beginners, people coming back after a break and lifters with more fat to lose.

Should you recalculate your macros as you lose weight?

Yes, when the scale says to, not on a schedule. Each pound lost lowers maintenance by about 12 calories. When your 7-day average stays flat for two weeks, add 2,000 steps a day first. If it's still flat two weeks later, drop 100 to 200 calories and take them from carbs.

How To Calculate Macros For Fat Loss (The 5-Step Formula)

To calculate macros for fat loss, you need five lines of arithmetic, not an app. Maintenance is your bodyweight in pounds × 12. Your daily target is maintenance minus 500. Protein is 1 g per pound of bodyweight, fat is 0.3 g per pound, and carbs fill whatever calories are left. For a 200-lb guy, that's 1,900 calories: 200 g protein, 60 g fat and 140 g carbs. Then track for two weeks and adjust to the data, not the mirror.

I posted these five steps in a reel with the on-screen line "I want to lose fat AND build muscle but I have no idea how to eat..." It's the method I used to get from 285 lb to about 200, and it's how I hold 8–10% body fat year-round. I'm 37, I'm a software engineer, and I weigh in every morning and log every macro.

How do you calculate macros for fat loss?

Run these five steps in order. Each one feeds the next.

Step 1: Maintenance calories = bodyweight × 12

A 200-lb guy maintains at about 200 × 12 = 2,400 calories a day. That's a starting estimate, not a measurement.

Step 2: Daily target = maintenance − 500

At 200 lb, 2,400 − 500 = 1,900. A pound of fat is about 3,500 calories, so 500 a day comes to about a pound a week. Five hundred is the default. Use 300 if you're already lean or life is stressful, or if you want to build muscle and lose fat at the same time. Here's how big of a calorie deficit to run.

Step 3: Protein = 1 g per pound of bodyweight

Set protein first, from your current weight. At 200 lb, that's 200 g, or 800 calories at 4 calories per gram. Protein matters more on a cut than at maintenance. A systematic review of lean lifters in a deficit put their needs at 2.3 to 3.1 g per kg of fat-free mass (Helms et al., 2014). At 200 lb and 20% body fat, that's about 167 to 225 g, so 200 fits. In a 4-week trial with a deficit of about 40%, young men on 2.4 g/kg gained 1.2 kg of lean mass and lost 4.8 kg of fat. The men on 1.2 g/kg gained 0.1 kg and lost 3.5 kg (Longland et al., 2016). More on how much protein you actually need, or use the protein calculator.

Step 4: Fat = 0.3 g per pound of bodyweight

At 200 lb, 0.3 × 200 = 60 g, or 540 calories at 9 calories per gram. Treat it as a floor, not a target.

Step 5: Carbs = the calories left over ÷ 4

Carbs = (target − protein × 4 − fat × 9) ÷ 4. At 200 lb, that's (1,900 − 800 − 540) ÷ 4 = 140 g. On a cut, carbs are the flexible macro: protein and fat are set by bodyweight, so carbs take whatever is left.

What do macros for fat loss look like for a 200-pound man?

1,900 calories: 200 g protein, 60 g fat and 140 g carbs.

Maintenance: 200 × 12 = 2,400 calories
Target: 2,400 − 500 = 1,900 calories
Protein: 200 g × 4 = 800 calories
Fat: 60 g × 9 = 540 calories
Carbs: (1,900 − 800 − 540) ÷ 4 = 140 g, or 560 calories
Check: 800 + 540 + 560 = 1,900

As percentages, that's about 42% protein, 28% fat and 30% carbs. 200 lb is about where I sit, but this isn't my intake. I maintain, so I don't eat 500 under.

On a smaller frame, carbs get tight. At 150 lb, the steps give 1,300 calories: 150 g protein, 45 g fat and about 74 g carbs. If you're also lean or stressed, the 300 setting from step 2 gives 1,500 calories and about 124 g of carbs.

If 200 g of protein is the number that scares you, the 200g Protein Blueprint is 4 simple meals that hit it.

Is bodyweight × 12 accurate for maintenance calories?

It's a starting estimate, usually within a few hundred calories, and two weeks of data correct the rest. The standard lab formula is Mifflin-St Jeor, built from 498 people whose resting burn was measured (Mifflin et al., 1990). A systematic review found it the most reliable common equation, within 10% of measured in more people than any other, but still with "noteworthy errors" for individuals (Frankenfield et al., 2005). Even at the same body composition, resting burn varies from person to person by a standard deviation of about 300 calories a day (Hall & Guo, 2017).

Here's how × 12 compares with Mifflin for a 37-year-old man at 5'8":

At 200 lb: Mifflin puts resting burn at about 1,807 calories. × 12 gives 2,400, about 1.33 times resting.
At 285 lb: resting burn is about 2,192. × 12 gives 3,420, about 1.56 times resting.

The heavier you are, the more daily movement × 12 quietly assumes. If a 285-lb guy who sits most of the day moved like the 200-lb guy (1.33 times resting), his maintenance would be about 2,910, and × 12 would run about 500 high. Protein still comes off current weight, so his is 285 g.

So the fix isn't a better formula. It's the scale. Weigh in every morning after the bathroom, before food, and judge only the 7-day average. Eat your target for two weeks. If the average falls about a pound a week, the estimate was right. If not, the data just told you your real maintenance.

How low should fat go when you're cutting?

Treat 0.3 g per pound as a floor, not a target. Eat more fat if you like and take those calories out of carbs, but don't go under it.

That's about 0.66 g per kg. In this formula, it puts fat at 26% to 31% of calories between 150 and 285 lb (28% at 200). That sits inside the research ranges:

The International Society of Sports Nutrition's review gives 25–35% of calories from fat, or 0.5–1.5 g per kg, for people in a general fitness program (Kerksick et al., 2018).
Evidence-based recommendations for natural bodybuilders in contest prep give 15–30% of calories from fat, protein at 2.3–3.1 g per kg of lean mass, and the rest from carbs (Helms, Aragon & Fitschen, 2014). Same structure as this formula.

The case against: a 2021 meta-analysis of 6 studies and 206 men found that low-fat diets lowered total and free testosterone compared with high-fat diets (Whittaker & Wu, 2021). Stronger By Science's write-up puts the low-fat groups at about 19% of calories from fat, against about 39%, and the drop at about 50 to 100 ng/dl. If testosterone is your priority, it suggests 30–40% of calories from fat, or about 1 g per kg when calories are low (Wolf, 2025).

Here's my read. At 28% of calories, 0.3 g per pound sits well above those 19% low-fat groups. It's below the 1 g per kg (about 91 g at 200 lb) some coaches prefer. If you'd rather eat more fat, raise it and drop carbs to match. Every 10 g of fat costs 22.5 g of carbs. The floor is the rule. The split above it is preference.

Do carbs matter for fat loss?

Not much, once calories and protein are set. Calories decide how much weight you lose. Protein decides how much of it is fat. The carb-to-fat split is mostly taste.

In the 12-month DIETFITS trial of 609 adults, the healthy low-fat group lost 5.3 kg and the healthy low-carb group lost 6.0 kg. The difference wasn't significant (Gardner et al., 2018). Kevin Hall's team at the NIH pooled 32 feeding studies (563 people) where all food was provided and calories and protein were matched. Lower-fat diets came out ahead by 26 calories a day of energy burn and 16 g a day of fat loss. The authors called the effect "so small as to be physiologically meaningless" (Hall & Guo, 2017). Low-carb has no metabolic edge.

That's why I don't do keto or no-carb. I lost the weight twice before, and it came back both times. What fixed it was a diet I could do forever, so pick a split you'd happily eat for years.

On a cut, carbs run low by design: about 1.5 g per kg at 200 lb, under the ISSN's 3–5 g per kg for general fitness (Kerksick et al., 2018). At 2,400 maintenance, with the same protein and fat, they go back up to 265 g.

When should you adjust your macros?

After two weeks, and only if the 7-day average stalls. As the caption put it: "Track 2 weeks and adjust to the DATA, not the mirror."

A stall means your 7-day average stays flat for 2 weeks. When that happens, add 2,000 steps a day first. If it's still flat 2 weeks later, drop 100 to 200 calories. One change at a time, and take the calories from carbs, since protein and fat move only when your weight does. Re-running the formula agrees: at 190 lb it gives 1,780, which is 120 below the 200-lb target.

That's the No-Guess Loop: Track, Review, Adjust, Build. Log the inputs, read the trend, change one thing, and keep the change when it works. In a review of 22 studies, self-monitoring of diet and weight was consistently linked to weight loss, though the authors rated the evidence weak on study design (Burke et al., 2011).

I once ate about 300 calories a day more than I thought, because the apples I bought weighed far more than the "standard apple" my tracking app assumed. Against a 500-calorie deficit, that's 60% of it gone. I only caught it because I track.

If the scale never moved from day one, the problem is usually tracking, not the formula. Here's why you might be not losing weight in a deficit.