Bulking and cutting get treated like identities in gym culture. You're either in a bulk or you're not. You're either "eating big to get big" or you're on a cut. The reality is simpler and less romantic: they're just two different caloric strategies with different macro targets, and many people are in the wrong one without realizing it.
Here's how to actually set your macros for each phase — and how to know which one you should be in.
The Foundation: TDEE
Before any of this makes sense, you need a baseline. Your Total Daily Energy Expenditure (TDEE) is the number of calories your body burns in a day accounting for your activity level. For a full breakdown of how to calculate it, see what is TDEE and why it's the only number that matters for fat loss. Everything else — bulking, cutting, maintenance — is calculated relative to this number.
You can estimate TDEE with any standard calculator (Mifflin-St Jeor is the most validated equation for most people). The output is an estimate, not a prescription — it's a starting point you adjust based on real-world results over 2–3 weeks.
Cutting: The Math
A cut is a sustained caloric deficit. You're consuming fewer calories than you burn, forcing your body to draw on stored energy — ideally fat — to make up the difference.
Deficit range: 300–500 calories below TDEE
- 300 cal deficit = approximately 0.6 lb/week of fat loss (sustainable, preserves more muscle)
- 500 cal deficit = approximately 1 lb/week (aggressive but manageable for most people)
- Beyond 500: muscle loss risk increases significantly, training performance drops, adherence collapses
Macro setup for a cut — example: 185 lb male, TDEE ~2,800 cal
| Target | Grams | Calories | |
|---|---|---|---|
| Calories | 2,400 | — | 2,400 |
| Protein | 1g per lb bodyweight (minimum) | 185g | 740 |
| Fat | 25–30% of total calories | 67–80g | 600–720 |
| Carbs | Remainder | 235–245g | 940–980 |
The non-negotiable on a cut: protein does not go down. For exact targets by bodyweight and goal, see how much protein per day you actually need. This is the most common mistake. When calories drop, people cut everything proportionally — including protein. Inadequate protein in a deficit accelerates muscle loss. Keep protein at or above 0.8–1g per pound of bodyweight regardless of how aggressive the deficit is.
Bulking: The Math
A bulk is a caloric surplus. You're consuming more than you burn, providing your body the raw materials and energy to support muscle growth beyond what's possible at maintenance.
Here's the part most people get wrong: the surplus doesn't need to be large.
Muscle protein synthesis — the process of actually building new muscle tissue — has a physiological ceiling. Research consistently shows that intermediate lifters gain roughly 0.5–1 lb of actual muscle per month under optimal conditions. That ceiling doesn't move because you eat more. Eating 800 calories above TDEE doesn't build muscle faster than eating 200 above — it just adds fat on top of whatever muscle you build.
Surplus range: 200–300 calories above TDEE for a lean bulk
- Keeps fat accumulation minimal while providing enough energy to support adaptation
- Any surplus beyond ~300 calories is statistically going toward fat storage, not muscle
Macro setup for a lean bulk — example: 185 lb male, TDEE ~2,800 cal
| Target | Grams | Calories | |
|---|---|---|---|
| Calories | 3,050 | — | 3,050 |
| Protein | 0.8–1g per lb bodyweight | 185g | 740 |
| Carbs | ~50% of total calories | 380g | 1,520 |
| Fat | Remainder | 88g | 790 |
Carbs get prioritized on a bulk because they're the primary fuel source for resistance training. More carbs = better training output = better stimulus for muscle growth.
The Dirty Bulk
A dirty bulk is what happens when "I'm in a bulk" becomes a reason to stop tracking.
It typically looks like: large, undefined caloric surplus, no macro targets, food quality doesn't matter because "calories are calories" and you're bulking anyway. The logic sounds convenient because it is — it's designed to be convenient, not effective.
The problem:
Fat accumulates fast. A 1,000-calorie daily surplus over 16 weeks is 112,000 excess calories — theoretically 32 lbs of fat, minus whatever goes to muscle (which, again, is physiologically capped). You end up in a longer, harder cut than you would have needed.
You lose the feedback loop. If you're not tracking, you don't know if your surplus is 200 calories or 1,200 calories. You can't adjust because you have no data.
It's not a strategy. It's the absence of one.
The dirty bulk is an excuse to eat whatever you want dressed up in fitness language. The research doesn't support large surpluses for muscle gain — and the people who advocate for it tend to be genetic outliers or enhanced athletes who aren't operating under the same physiological constraints.
Most People Should Cut Before They Ever Bulk
This is the part most gym content won't say directly, so here it is:
If you're above 15% body fat and your goal is to look better — you probably don't need a bulk. You need a cut.
Here's why this matters:
Body recomposition research (Barakat et al., 2020; Schoenfeld et al., 2018) demonstrates that individuals above roughly 15–18% body fat can build muscle and lose fat simultaneously — without a surplus. The mechanism is straightforward: excess body fat provides stored energy that can be mobilized to fuel muscle protein synthesis even in a slight deficit. You don't need external calories to power adaptation if your body already has stored fuel available.
The definition and aesthetics most people are after — visible muscle, reduced body fat — are already there under the fat. A bulk doesn't build new shape so much as it adds mass on top of existing shape. If the existing shape is buried under fat, more mass isn't the answer.
The exception: Lean, experienced lifters (sub 12% body fat for men, sub 20% for women) who have genuinely plateaued — strength progress has stalled, muscle growth has stopped — are appropriate candidates for a calculated lean surplus. At that body composition, stored energy is limited, and a modest surplus provides real benefit.
But that's not most people reading this. Most people have room to cut first.
How to Know Which Phase You're In
| Cut | Lean Bulk | |
|---|---|---|
| Body fat % | Men >15%, Women >25% | Men <12%, Women <20% |
| Goal | Lose fat, reveal existing muscle | Build muscle, maintain lean body comp |
| Caloric strategy | 300–500 below TDEE | 200–300 above TDEE |
| Protein | 0.8–1g/lb (non-negotiable) | 0.8–1g/lb (non-negotiable) |
| Timeline | 8–16 weeks, then reassess | 12–20 weeks, then reassess |
| Sign it's working | Scale down 0.5–1 lb/week, strength maintained | Scale up ~0.25–0.5 lb/week, strength improving |
If your body fat falls somewhere in the middle (12–15% for men), body recomposition at near-maintenance calories is often the best option — slight deficit on rest days, slight surplus on training days.
Tracking Across Phases
The macro targets for a cut and a lean bulk are meaningfully different — primarily in total calories and carb allocation. Trying to manually recalculate and hit those targets from memory doesn't work past the first week. The only way to know if you're actually in your target range is to track.
That's straightforward when you're eating food you prepared. It gets harder when you're traveling, eating at a restaurant, or working from a base dining facility. You don't always have labels or exact gram weights.
Logging by description handles that better than database searches. Instead of hunting for the right entry:
"8oz chicken breast, 1 cup white rice, olive oil maybe 1 tbsp"
"protein shake, 2 scoops whey, 1 cup whole milk, banana"
FuelLog parses those descriptions against USDA nutritional data — AI fills in where standard database entries fall short — and returns the full macro breakdown. You know where you stand against your targets without spending five minutes in a dropdown menu.
On Premium, you send it as a text from wherever you're eating. One message, full breakdown.
The Short Version
- Cut: 300–500 cal below TDEE. Keep protein high. 8–16 weeks.
- Lean bulk: 200–300 cal above TDEE. Prioritize carbs. 12–20 weeks.
- Dirty bulk: Not a strategy. Just undisciplined eating with a fitness label.
- Most people above 15% body fat should cut first — the physique you want is already there. Shed the fat before adding more on top.
Pick the right phase for where you actually are. Set the targets. Track them.
Sources
- Schoenfeld BJ, et al. "Body composition changes associated with fasted versus non-fasted aerobic exercise." Journal of the International Society of Sports Nutrition. 2014;11:54.
- Barakat C, et al. "Body Recomposition: Can Trained Individuals Build Muscle and Lose Fat at the Same Time?" Strength and Conditioning Journal. 2020;42(5):7–21.
- Hall KD. "Body fat and fat-free mass inter-relationships: Forbes's theory revisited." British Journal of Nutrition. 2007;97(6):1059–1063.
- Morton RW, et al. "A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults." British Journal of Sports Medicine. 2018;52(6):376–384.
- Helms ER, et al. "Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation." Journal of the International Society of Sports Nutrition. 2014;11:20.