A lean bulk only needs a small calorie surplus: roughly 10 to 20 percent above maintenance if you are a beginner or intermediate lifter, and closer to 5 to 10 percent if you have been training for many years. At 2,800 kcal maintenance, that works out to about 150 to 550 kcal a day. Whether your number is right is decided by your trend weight, not by a calculator: it should rise by about 0.25 to 0.5 percent of your body weight per week.
Those ranges come from a review on nutrition for bodybuilders in the off-season (Iraki et al. 2019). In this article I explain why the surplus should stay small, how to turn a target rate into a calorie number, and how to tell after two or three weeks whether you need to adjust.
Why the surplus should be small
Muscle grows slowly, and your body does not build it faster just because more energy is available. Whatever exceeds what muscle growth needs mostly ends up as fat. A "dirty bulk" with a big surplus mainly puts more weight on the scale, not more muscle on your frame.
A study in Norwegian elite athletes shows this quite directly (Garthe et al. 2013). Over 8 to 12 weeks, both groups followed the same strength program. One group ate about 3,585 kcal a day after nutrition counseling, the other ate freely at about 2,964 kcal. The group eating more gained clearly more weight (3.9 versus 1.5 percent of body weight), but their fat mass rose by 15 percent instead of 3 percent. Lean mass gains did not differ between the groups. The extra 600 or so kcal a day mostly bought fat.
Another review reaches a similar conclusion (Slater et al. 2019): nobody knows exactly how large a surplus maximizes muscle growth. The authors therefore suggest a cautious surplus of about 1,500 to 2,000 kilojoules a day, roughly 360 to 480 kcal.
Every extra kilo of fat you gain while bulking has to come off again during your cut. That costs weeks of being hungry and not building muscle.
How many calories by training experience
The table below summarizes the recommendations from Iraki et al. The right-hand column is a worked example for 2,800 kcal maintenance, not a personal recommendation.
| Training status | Surplus over maintenance | Target rate per week | Example at 2,800 kcal maintenance |
|---|---|---|---|
| Beginner and intermediate | +10 to 20 % | 0.25 to 0.5 % of body weight | 3,080 to 3,360 kcal |
| Advanced (many years of training) | +5 to 10 % | about 0.25 % of body weight | 2,940 to 3,080 kcal |
The closer you are to your genetic ceiling, the less muscle you can add per month, and the smaller your surplus should be. A beginner tends to benefit from the upper end, a lifter with ten years under the bar from the lower end.
From target rate to calories
I find it more practical to start not from a percentage of maintenance but from the rate at which your weight should rise. You can check that rate directly against your trend line later. The conversion is simple:
Daily surplus = rate per week × body weight × 7,700 ÷ 7
The 7,700 kcal per kilogram (about 3,500 kcal per pound) is a common approximation for the energy in a kilogram of body weight. It was derived for weight loss and is known to be imprecise (Hall 2008). Muscle stores much less energy per kilogram than fat: Slater et al. put it at about 5,000 to 5,200 kJ per kilogram of muscle. For a lean bulk the formula is therefore on the generous side, which does not matter as long as you adjust based on your trend.
Worked example: 80 kg (176 lb) body weight
These numbers are an example, not a target for you:
| Rate per week | Gain per week | Daily surplus | At 2,800 kcal maintenance |
|---|---|---|---|
| 0.25 % | 0.20 kg (0.44 lb) | approx. 220 kcal | approx. 3,020 kcal |
| 0.35 % | 0.28 kg (0.62 lb) | approx. 310 kcal | approx. 3,110 kcal |
| 0.5 % | 0.40 kg (0.88 lb) | approx. 440 kcal | approx. 3,240 kcal |
These surpluses equal about 8, 11 and 16 percent of maintenance, which puts them inside the ranges from the table above. You can run the same numbers for yourself in the bulk and cut calorie calculator.
Maintenance is the real unknown
Every calculation starts with maintenance calories, and at the beginning that number is only an estimate. Formulas like Mifflin-St Jeor with an activity factor, as used in the TDEE calculator, work well for many people but are off by several hundred calories for some. An error of 300 kcal is as big as a planned surplus of 300 kcal.
So treat your starting number as just that: a start. It gets more accurate once you log your intake for a few weeks and compare it with how your weight develops. If you average 3,000 kcal and your trend stays flat, your maintenance is about 3,000 kcal, whatever the formula said.
Adjust after two to three weeks
The most important part of a lean bulk does not happen on day one but in week three. By then you have enough weigh-ins to see your actual rate.
Don't overrate the first week
When you raise calories, especially through carbs, your glycogen stores fill up, and your body stores water along with the glycogen. In the first few days the scale often jumps more than your surplus can explain. It is the same mechanism as after a hard workout, which I describe in Weight gain after a workout. If you start creatine at the same time, you get an extra step on top, see Does creatine make you gain weight?.
Daily swings of a kilo or more are normal (Why your weight fluctuates daily). Comparing two daily readings tells you nothing about your rate. Look at your trend weight, the smoothed line (Trend weight instead of the daily number), and at its slope over at least two weeks.
How to correct
The correction uses the same formula as above, just in reverse. An example at 80 kg with a target of 0.28 kg per week:
- Trend rises 0.45 kg per week: that is 0.17 kg too much, so about 0.17 × 7,700 ÷ 7 ≈ 190 kcal. Cut your intake by about 150 to 200 kcal.
- Trend is flat: you are missing the full 0.28 kg, about 300 kcal. Add 150 to 200 kcal in one step and check again after two more weeks.
- Trend is on plan: change nothing. That is the normal case if your starting number was good.
I prefer small steps followed by another two weeks of waiting over adjusting every week. Otherwise you end up reacting to noise instead of the trend.
Macros on a lean bulk
Calories decide whether you gain. Macros help decide what you gain. Iraki et al. recommend for the off-season:
- Protein: 1.6 to 2.2 g per kilogram of body weight per day, spread over 3 to 6 meals
- Fat: 0.5 to 1.5 g per kilogram
- Carbs: the rest, at least about 3 to 5 g per kilogram
More protein than you need is usually not harmful, but it costs calories you could otherwise spend on carbs and thus on your training. Work out your ranges in the protein calculator or the macro calculator.
Common lean bulk mistakes
- A big surplus out of impatience. Gaining weight faster does not mean building muscle faster, see Garthe et al.
- Changing calories after one bad day. A high morning reading after pizza and salt is water, not fat.
- Never adjusting. Your maintenance rises with your weight and with more everyday movement. What fit in month one may not fit in month four.
- Letting the bulk run forever. Plan an end date or a goal weight so your lean bulk does not turn into creeping fat gain.
How I run this with Lean is law
In Lean is law you create a "Bulk" phase and choose your rate as a percentage of your trend weight per week. The default is 0.35 percent, and the sensible range is 0.25 to 0.5 percent. If your trend rises faster than 0.5 percent, the app warns you that you are gaining more fat than necessary. Your weekly rate sits right on the Today screen, calculated from the trend rather than from single readings.
With Pro, the app calculates your maintenance adaptively from your logged intake and your trend and derives your calorie target for the phase from it. At its core that is the same math as in this article, without you having to redo it every week.
Sources
- Iraki J, Fitschen P, Espinar S, Helms E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports (Basel). 2019;7(7):154. PubMed
- Garthe I, Raastad T, Refsnes PE, Sundgot-Borgen J. Effect of nutritional intervention on body composition and performance in elite athletes. Eur J Sport Sci. 2013;13(3):295-303. PubMed
- Slater GJ, Dieter BP, Marsh DJ, Helms ER, Shaw G, Iraki J. Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training. Front Nutr. 2019;6:131. PubMed
- Hall KD. What is the required energy deficit per unit weight loss? Int J Obes. 2008;32(3):573-576. PubMed