Bulking vs Cutting: The Complete Nutrition Guide for Muscle Gain and Fat Loss

Bulking vs cutting in brief

Three numbers carry most of this page. How fast to lose weight on a cut, how much protein stops being useful on a bulk, and how big a deficit stops muscle growth.

Every figure on this page about bulking vs cutting comes from a PubMed abstract listed at the end. The body fat thresholds for choosing a phase and the example meal plans are coaching rules of thumb, and the page says so where they appear.

What this bulking vs cutting guide covers

What bulking and cutting actually mean

Your body needs a certain number of calories a day to stay the same weight. That is your maintenance. Eat more than that for weeks, and you gain weight. Eat less, and you lose it. Bulking is deliberately eating above maintenance while lifting, so the extra energy has a reason to become muscle. Cutting is deliberately eating below maintenance while lifting, so the body burns fat and keeps the muscle. Neither is a diet in the usual sense. They are phases, and most people who lift for years alternate between them.

What is bulking and cutting for, if you could just eat at maintenance? Because muscle is expensive to build and fat is easy to gain. Lifting in a surplus gives the body spare energy and raw material, and the research shows a surplus does help growth even on its own (PMID 31482093). But the body does not put every extra calorie into muscle. In 39 elite athletes on an 8 to 12 week gain phase, the group eating about 600 kcal a day more gained 3.9 percent body weight against 1.5 percent, yet the extra was mostly fat. Lean mass gain was the same in both groups (PMID 23679146). That is the reason cutting exists: to remove the fat that came with the muscle.

Here is the example lifter for this page. Meet Jordan. Jordan is 80 kg, about 15 percent body fat, has lifted for two years, and eats about 2 600 kcal a day to stay at 80 kg. Jordan wants to look leaner and be bigger, and is not sure which to do first. Everything below is worked out for Jordan.

The difference between bulking and cutting, in one table

Should I bulk or cut first? How to tell

Bulk vs cut is the question most people actually have, and the answer is simpler than the forums make it. Look at two things: how much fat you carry now, and how long you have been lifting. The fatter you are, the more a cut gives back, because a surplus from a high starting point mostly adds fat. The leaner you are, the better a bulk works, because you have room to gain before you look soft. Beginners are a special case covered below.

How do you know your body fat without a scan? Rough guides are fine here. A man around 12 percent has visible abs in good light. Around 17 percent has a flat stomach but no definition. Over 22 percent has a soft layer you can grab. For women, add about 8 to 10 points to each of those. The exact number matters less than which row you are in. If you want a number, the BMI calculator is a start, and a cheap caliper or a smart scale will put you in the right row even if the decimal is wrong.

If you are skinny fat: bulk or cut?

Skinny fat means not much muscle and a soft middle, which usually comes from very little lifting. If that is you and you have under six months of training, the answer is neither. Eat at maintenance with high protein and lift three or four days a week. New lifters build muscle and lose fat at the same time, and a formal phase is not needed yet. After six months, use the table. Most skinny fat lifters end up in the Soft row and do best with a short cut followed by a long, slow bulk.

Bulk or cut first, if you are new?

In the first year, lifting itself does most of the work. In a 4 week study, 20 young men ate 40 percent below maintenance at 2.4 g of protein per kg. They still gained 1.2 kg of lean mass and lost 4.8 kg of fat, because the training was new and the protein was high (PMID 26817506). That does not happen to someone with five years of training. So beginners should set calories at maintenance or a small deficit, eat plenty of protein, and let the training sort it out. Intermediate lifters pick a phase.

Bulking nutrition: how to gain muscle without gaining a belly

The job of a bulk is to gain weight slowly enough that most of it is muscle. The review of off season bodybuilding nutrition puts the surplus at about 10 to 20 percent above maintenance. The target gain is 0.25 to 0.5 percent of body weight a week for new and intermediate lifters, and slower for advanced lifters (PMID 31247944). For Jordan that is 260 to 520 extra calories a day and 0.2 to 0.4 kg a week. That is slow. It is also the point.

Why not eat more and grow faster? Because the trials say the extra does not become muscle. In the elite athlete study, the group fed a planned surplus gained more than twice the weight of the group eating freely. Lean mass gain was the same. Fat gain was five times higher, 15 percent against 3 percent (PMID 23679146). In 11 bodybuilders, the high energy group did gain more muscle, 2.7 percent against 1.1 percent in 4 weeks, but also gained 7.4 percent body fat against 0.8 percent (PMID 31915482). More calories buy a little more muscle and a lot more fat.

Protein on a bulk

This is the number people get wrong in the expensive direction. In the review of 49 trials, protein helped, but above about 1.6 g per kg a day there was no further gain in lean mass (PMID 28698222). The off season review allows up to 2.2 g per kg as a buffer (PMID 31247944). For Jordan that is 130 to 175 g a day. Eating 250 g a day on a bulk is not harmful, but it is money and stomach space that could go to carbohydrate, which is what fuels the training that builds the muscle.

Clean bulk, dirty bulk, lean bulk

These are not scientific terms, so here is how coaches use them. A dirty bulk is eating anything to get the scale up fast. It works for weight and fails for body composition, exactly as in the trials above. A clean bulk is the same calories from mostly whole food. A lean bulk is the slow 10 to 20 percent surplus described here. The names matter less than the weekly number on the scale. If it is going up more than 0.5 percent a week, you are gaining fat whatever you call it.

Cutting nutrition: how to lose fat and keep the muscle

The job of a cut is to lose fat slowly enough that the muscle stays. Two numbers set the pace. The contest prep review recommends losing 0.5 to 1 percent of body weight a week to keep muscle (PMID 24864135). The slow versus fast trial shows why the lower end is better. Athletes losing 0.7 percent a week gained 2.1 percent lean mass and improved their lifts. Athletes losing 1 percent a week held lean mass flat (PMID 21558571). For Jordan, 0.7 percent is about 0.55 kg a week.

The second number is the deficit itself. The meta analysis of lifting trials in a deficit found that lean mass gains were impaired compared with lifters at maintenance. The regression put the point where growth stops at about 500 kcal a day below maintenance. Strength gains were not affected (PMID 34623696). So a cut of up to 500 kcal lets you keep, and sometimes still add, muscle. A cut of 800 or 1 000 kcal does not, however much protein you eat.

Protein on a cut goes up, not down

When calories drop, protein needs rise. The review of lean, dieting, resistance trained athletes concluded that 2.3 to 3.1 g per kg of lean mass a day is likely needed, with the higher end for leaner people and harder diets (PMID 24092765). The clearest trial is the one on 40 young men eating 40 percent below maintenance for 4 weeks while training six days a week. The group at 2.4 g per kg of body weight gained 1.2 kg of lean mass and lost 4.8 kg of fat. The group at 1.2 g per kg gained 0.1 kg of lean mass and lost 3.5 kg of fat (PMID 26817506). Double the protein, more fat lost, muscle gained instead of held.

Why the cut slows down

After a few weeks of dieting, the same calories stop producing the same loss. Part of that is simple: you weigh less, so you burn less. Part of it is adaptation. Hormones, movement and resting metabolism all drop a little more than the weight loss alone explains (PMID 24571926). The extreme example is the Biggest Loser study, where resting metabolism was about 500 kcal a day lower than body size predicted six years later (PMID 27136388). That was after losing 58 kg in 30 weeks, so it is not what happens on an 8 week cut. But it is the reason a cut should be short, moderate and followed by a return to maintenance, not pushed for months.

Body recomposition: can you bulk and cut at the same time?

Yes, for some people, some of the time. Recomposition means gaining muscle and losing fat in the same period while eating around maintenance. The trials where it happens have one of three things in common: the people are new to lifting, they carry a lot of fat, or they eat a lot of protein. The 4 week deficit trial above is the clearest case. New, hard training and 2.4 g of protein per kg produced 1.2 kg of lean mass and 4.8 kg of fat loss at the same time (PMID 26817506).

It also happens in trained people when protein is very high. Forty eight trained men and women ate either about 2.3 or about 3.4 g of protein per kg a day for 8 weeks on a heavy split routine. The high protein group ate more calories in total, yet lost 1.7 kg of fat and 2.4 points of body fat percentage. The normal protein group gained 1.3 kg of body weight and lost 0.3 kg of fat (PMID 26500462). More protein, more total food, less fat.

The catch is speed. Recomposition is slow in both directions. A trained lifter at maintenance might gain 1 kg of muscle and lose 1 kg of fat in three months, and the scale will not move, which is hard to live with. A bulk followed by a cut covers more ground in the same time. Recomp is the right call for beginners, for anyone coming back after a long break, and for people who cannot face the scale going up. For everyone else, phases are faster.

How long to bulk and cut, and when to switch

A bulk should be long and a cut should be short. That follows from the rates. At 0.25 to 0.5 percent a week, a useful bulk needs 16 weeks or more to gain a few kilos (PMID 31247944). At 0.7 percent a week, a cut removes the fat from that bulk in 6 to 10 weeks (PMID 21558571). Long cuts are where metabolic adaptation builds and muscle starts to go, so keep them under 12 weeks and take a break at maintenance if more fat needs to come off (PMID 24571926).

When to stop bulking

Stop when one of three things happens. You reach the top of the Soft row in the body fat table, around 20 percent for men and 30 for women. Your weekly gain has been over 0.5 percent for three weeks and you cannot bring it down without feeling hungry. Or you have been bulking 24 weeks and want a change. The scale number itself does not matter. The rate and the mirror do.

When to stop cutting

Stop when you reach the body fat you wanted, when the cut has run 12 weeks, or when your lifts drop for two weeks in a row. The last one matters. Strength is usually protected in a moderate deficit (PMID 34623696), so losing it is a sign the deficit is too deep or has run too long. Spend two weeks at maintenance, then either start a bulk or, if more fat needs to go, cut again.

Bulk or cut calculator: your phase, calories and protein

Put in your weight, a rough body fat percentage, your maintenance calories and how long you have lifted. The calculator picks a phase using the body fat table, then gives the calorie range, the weekly rate to aim for and the protein range from the trials and reviews on this page. If you do not know your maintenance, the calorie calculator gives an estimate, and two weeks of a stable scale confirms it.

Bulking vs cutting for women

The same rules apply, with two changes. First, the body fat thresholds are higher. Women carry more essential fat, so the rows in the table shift up by about 8 to 10 points. A lean woman is under 20 percent, a soft one over 27, and a cut is the usual call over 32. Second, the absolute numbers are smaller because body weight and maintenance calories are usually lower. A 10 to 20 percent surplus might be 200 to 350 kcal, and a 500 kcal deficit is a bigger share of the day. Many women do better with a 300 to 400 kcal deficit and a slightly longer cut.

The response to the training itself is not different. A review of 10 studies found no difference in muscle growth between men and women on the same lifting program, and women showed larger relative upper body strength gains (PMID 32218059). So the fear that bulking will make a woman bulky is not supported. At 0.25 to 0.5 percent a week, a 60 kg woman gains 150 to 300 g a week, and most of that, with the protein in place, is muscle.

Five bulking and cutting mistakes that waste a phase

1. Bulking at plus 1 000 calories

A big surplus gets the scale moving and feels like progress. The trials show the extra is fat. The planned surplus group in the elite athlete study gained no more lean mass than the group eating freely, and five times the fat (PMID 23679146). Keep it at 10 to 20 percent and let the scale rise slowly.

2. Cutting at minus 1 000 calories

A deficit over about 500 kcal a day stops muscle gain and starts to threaten the muscle you have (PMID 34623696). Faster weight loss also held lean mass flat where slower loss grew it (PMID 21558571). The fast cut saves four weeks and costs the thing you were cutting to show off.

3. Dropping protein on the cut

Protein needs go up when calories go down, to 2.3 to 3.1 g per kg of lean mass (PMID 24092765). Cutting protein along with everything else is the most common reason a cut ends with smaller arms and the same waist.

4. Switching phases every three weeks

At 0.25 to 0.5 percent a week, three weeks of bulking gains under a kilo, most of it water and glycogen. Then the cut removes it. Nothing was built. A bulk needs 16 weeks or more to be worth the cut that follows it.

5. Judging by the daily weigh in

Weight moves a kilo a day with water, salt and food in the gut. Weigh every morning, average the week, and compare weekly averages. The rate matters, not the number, and the rate only shows up in the average.

Verdict: cut if you can grab it, bulk if you cannot, and go slow either way

Bulk vs cut is a decision about where you are, not about which is better. Carrying visible fat: cut for 6 to 12 weeks at no more than 500 kcal below maintenance, with protein high, losing about 0.7 percent a week. Lean or normal: bulk for 16 to 24 weeks at 10 to 20 percent above maintenance, gaining 0.25 to 0.5 percent a week. New to lifting: do neither yet. Eat at maintenance with high protein and let the first year of training do both jobs.

How to train in each phase is on cutting vs bulking training. Setting the maintenance number the whole plan hangs on is on calories and energy balance and the calorie calculator.