When bulking, aim to gain about 0.25 to 0.5 percent of your body weight per week. In your first year of training you can lean toward the upper end; after several years, around 0.25 percent is the better choice. At 80 kg (176 lb) that is 0.2 to 0.4 kg per week, or roughly 1 to 1.7 kg (2 to 3.8 lb) a month. You can only measure this rate on your trend weight, not on single daily readings.
The 0.25 to 0.5 percent range comes from a review on nutrition for bodybuilders in the off-season (Iraki et al. 2019). The authors recommend it for beginners and intermediates and advise advanced lifters to go slower. Below I show how to translate that into your years of training, what gaining too fast costs you, and how to read your real rate.
Why percent instead of kilos
Half a kilo per week is something different for someone at 60 kg than for someone at 100 kg. Percentages scale with body weight, so they work for light and heavy lifters, women and men alike. That is why I think in percent first and convert to kilos or pounds afterward.
It also matters that we are talking about the rate of your trend weight. Your weight swings by a kilo or more from day to day, as described in Why your weight fluctuates daily. A gain of 0.3 kg per week disappears completely in that noise as long as you compare two single morning readings.
Table: rate of gain by training age
Iraki et al. only distinguish two groups: beginners and intermediates at 0.25 to 0.5 percent per week, and advanced lifters at about 0.25 percent. The finer split by years in the table below is my own interpretation within that range, not a figure from a study. "Training years" means years of consistent, serious lifting, not the time since you first bought a gym membership.
| Training status |
Rate per week |
Reasoning |
| Year 1 (beginner) |
0.4 to 0.5 % |
Largest growth potential, a bigger surplus is most likely to become muscle |
| Years 2 to 3 |
0.3 to 0.4 % |
Progress slows, the middle of the range is a good compromise |
| Year 4 and beyond |
about 0.25 % |
Close to your personal ceiling, any extra tends to end up as fat |
Iraki et al. state explicitly that beginners may benefit from larger surpluses while advanced bodybuilders do better with conservative ones. As a warning sign, they note that gaining 2 kg a month may be too much for advanced lifters.
Converted to kilos
The values below are a worked example. I count a month as 4.35 weeks.
| Body weight |
0.25 % per week |
0.35 % per week |
0.5 % per week |
| 60 kg (132 lb) |
0.15 kg (0.7 kg/month) |
0.21 kg (0.9 kg/month) |
0.30 kg (1.3 kg/month) |
| 70 kg (154 lb) |
0.18 kg (0.8 kg/month) |
0.25 kg (1.1 kg/month) |
0.35 kg (1.5 kg/month) |
| 80 kg (176 lb) |
0.20 kg (0.9 kg/month) |
0.28 kg (1.2 kg/month) |
0.40 kg (1.7 kg/month) |
| 90 kg (198 lb) |
0.23 kg (1.0 kg/month) |
0.32 kg (1.4 kg/month) |
0.45 kg (2.0 kg/month) |
| 100 kg (220 lb) |
0.25 kg (1.1 kg/month) |
0.35 kg (1.5 kg/month) |
0.50 kg (2.2 kg/month) |
That looks like very little, and that is exactly the point. A lean bulk is slow. Most people who think they are gaining "too slowly" are actually right on plan and got spooked by a weekend of eating less.
What gaining too fast costs you
Gaining weight faster does not mean building muscle faster. A study in elite athletes compared two groups doing the same strength training for 8 to 12 weeks (Garthe et al. 2013). The group eating more gained 3.9 percent of body weight, the other 1.5 percent. Lean mass rose in both groups with no difference, but fat mass went up by 15 percent instead of 3 percent.
Worked example: a six-month bulk
A lifter at 80 kg bulks for 26 weeks. The numbers are a simplified example without compounding:
- At 0.25 percent per week: 0.2 kg × 26 = about 5.2 kg gained
- At 0.5 percent per week: 0.4 kg × 26 = about 10.4 kg gained
Nobody can tell you in advance how much of that is muscle. But Garthe et al. show the direction: the extra gain from the faster rate is mostly fat. Suppose the additional 5.2 kg were all fat and you want to lose it again in a cut. At a cutting rate of 0.7 percent per week, about 0.6 kg at around 90 kg, that takes a little over 8 extra weeks of dieting. That is two months spent only on undoing the excess from your bulk.
Iraki et al. point to exactly this: too much fat gained in the off-season makes the following diet longer or harder.
The role of your body fat
Besides training age, your starting point matters too. A classic analysis by Forbes shows that when people are overfed, lean individuals put on a much larger share of the gain as lean mass than people with a lot of body fat: about 60 to 70 percent versus 30 to 40 percent (Forbes 2000). These data come from overfeeding studies, not from bodybuilding, but the direction is clear: the more body fat you already carry, the less a fast bulk pays off.
If you are unsure whether you should start with a bulk at all, the FFMI calculator together with a body fat estimate helps you decide.
How to check your rate on the trend
Plan three steps to turn the table above into a real rate.
1. Derive your calorie target from the rate
Your target rate gives you the daily surplus: rate × body weight × 7,700 ÷ 7. At 80 kg and 0.35 percent that is about 310 kcal above maintenance. How to get there, and why 7,700 kcal is only an approximation, is covered in detail in Lean bulk calories. You can run your own numbers in the bulk and cut calorie calculator.
2. Measure for at least two weeks
Weigh yourself every morning under the same conditions if you can. In the first days of a bulk the scale often rises faster than planned, because more carbs fill your glycogen stores along with water. That step is not fat. The rate that counts is the one afterward.
3. Read the slope of your trend
Trend weight smooths out daily readings so the real direction becomes visible. How it works is explained in Trend weight instead of the daily number, and which smoothing method suits which purpose in How to calculate trend weight. With the weight trend calculator you can paste in your readings without an app and read your weekly rate.
If your rate is clearly above target after two to three weeks, drop 150 to 200 kcal a day. If it is clearly below, add the same amount. Then wait another two weeks.
Frequently asked questions
Can I gain faster than 0.5 percent as a beginner?
You can, but it usually is not worth it. Beginners cannot build muscle at any speed they like either. If you gain much faster than 0.5 percent per week, you are very likely adding more fat than necessary.
What if I'm not gaining despite a surplus?
Then it is not a surplus. Almost always your real maintenance is higher than estimated, or your intake is lower than you think. Log carefully for a while and compare with your trend.
Does the table apply to women?
The percentages from Iraki et al. do not differ by sex, and because they are percentages, the rate scales with your body weight. Women also have cycle-related fluctuations that can distort the trend for a few days. It helps to compare the same phases of your cycle.
How Lean is law handles this
In Lean is law you create a "Bulk" phase and set the rate directly as a percentage of your trend weight per week. The default is 0.35 percent; the app treats 0.25 to 0.5 percent as the sensible range and warns you if your trend climbs faster than 0.5 percent. The weekly rate is a regression over the last 14 trend values, so a single outlier barely moves it. That way you see every morning whether you are on plan without doing the math yourself.
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
- Forbes GB. Body fat content influences the body composition response to nutrition and exercise. Ann N Y Acad Sci. 2000;904:359-365. PubMed
