How to calculate calories for bulking: surplus, rate

Step 1: maintenance calories

Start with the Mifflin-St Jeor equation: for men 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5, for women "− 161" instead of "+ 5". Multiply by a physical activity level (PAL) from the FAO/WHO/UNU report: 1.40-1.69 for a sedentary or light lifestyle, 1.70-1.99 for active, 2.00-2.40 for vigorous. The report gives office workers as an example of a sedentary lifestyle, and says an hour a day of moderate to vigorous exercise raises average PAL from 1.55 (sedentary) to 1.75 (active).

[3][4]

The equation was built from measurements of 498 healthy adults aged 19 to 78, of normal weight and with obesity, so for a lifter it is an estimate.

[3]

If you have logged food and weighed yourself for a few weeks at a stable weight, your average daily calories from that period are a better starting point than the equation.

Step 2: surplus size and rate of gain

Surplus and rate of gain by training age (Iraki et al., 2019, natural bodybuilders in the off-season)
Training age	Surplus over maintenance	Bodyweight gain per week
Novice and intermediate	+10-20%	about 0.25-0.5%
Advanced	+5-10%	about 0.25%

[1]

The authors write that a larger surplus may suit novices better, because muscle growth slows as you become more advanced, and that advanced lifters should be more conservative with both the surplus and the weekly gain, or more conservative still if they gain clear amounts of fat. The review does not define these groups in years of training.

[1]

The review also relays the conclusion of Garthe and colleagues, whose study is described below: for highly trained athletes, a surplus of 200-300 kcal a day may be more appropriate than 500 kcal. At a 3,070 kcal maintenance, 500 kcal is about 16%: inside the novice and intermediate range, and above the advanced range (5-10%, about 150-310 kcal).

[1][2]

What a study of two surpluses showed

Garthe and colleagues followed 39 elite athletes, about 19 years old, for 8-12 weeks while they added four strength sessions a week. The group on a meal plan ate about 3,585 kcal a day; the group eating freely, about 2,964 kcal, roughly 600 kcal less and a very small surplus.

[2][1]

The meal-plan group gained 3.9% of bodyweight, about 0.3-0.5% a week, the other group 1.5%. Lean mass rose 1.7 kg against 1.2 kg, a difference that was not statistically significant. Fat mass rose 1.1 kg against 0.2 kg. In these trained athletes, the extra food went mostly to fat.

[2][1]

Step 3: calories, protein, fats, carbs

Calories: maintenance plus the surplus from the table.
Protein: 1.6-2.2 g per kg of bodyweight a day, at least 1.6 g/kg.
Fats: 20-35% of calories; the review's abstract also gives 0.5-1.5 g/kg a day.
Carbs: the remaining calories, at least 3-5 g/kg a day.

[1]

[1][3][4]

Step 4: track the rate, adjust the surplus

Iraki and colleagues recommend judging the average weekly change from daily, or several weekly, weigh-ins and adjusting intake to changes in body composition.

[1]

One weekly average gives you no rate. Change the target only when at least two consecutive week-to-week changes fall outside your range.

Novice and intermediate: above 0.5% of bodyweight a week, lower the surplus towards 10%; below 0.25%, raise it towards 20%.
Advanced: the target is about 0.25% a week. Clearly faster: lower the surplus towards 5%, or below if you are clearly gaining fat. Clearly slower: raise it towards 10%.
Rate inside the range for your training age: keep the target.

[1]

When to stop or hold the bulk

The review gives no body-fat threshold and no off-season length at which a bulk must end, so the points below are this guide's decision rules, not findings from research.

[1]

You reached the bodyweight you planned: move to maintenance or a cut.
The rate stays above the range even after you cut the surplus: go back to maintenance calories and assess your body composition.
You plan a cut next: calculate it from your current weight, not your pre-bulk weight.

How CalXd does it

In CalXd you set a goal to cut, bulk or maintain. The app calculates your daily calorie and macro targets from your profile and goal; you can also set the calorie target yourself. You log your weight and see it on a chart with a 7-day average line.

At most once every 7 days, CalXd reads your weight trend over the last 3 weeks. When there is enough data, it suggests a new calorie target and you decide whether to apply it. The first suggestion comes no earlier than 4 weeks into a goal.

Questions

How many calories should I eat to bulk?

Maintenance plus 10-20% if you are a novice or intermediate, or plus 5-10% if you are advanced, according to the 2019 review by Iraki and colleagues. For the example 80 kg man with a 3,070 kcal maintenance, a 10% surplus gives about 3,380 kcal.

How fast should I gain weight on a bulk?

About 0.25-0.5% of bodyweight a week for novices and intermediates, about 0.25% for advanced lifters. At 80 kg that is 0.2-0.4 kg a week. In the study by Garthe and colleagues, a bigger surplus gave faster gain, but the extra weight was mostly fat.

Is a 500 kcal surplus a good start?

It depends on your training age and maintenance. Garthe and colleagues, cited in the Iraki review, conclude that for highly trained athletes 200-300 kcal a day may be more appropriate than 500 kcal. At a 3,070 kcal maintenance, 500 kcal is about 16%: inside the novice and intermediate range (10-20%), above the advanced range (5-10%).

How much protein do I need on a bulk?

1.6-2.2 g per kg of bodyweight a day, and no less than 1.6 g/kg, according to the Iraki review for bodybuilders in the off-season. At 80 kg that is 128-176 g.

How to calculate calories for bulking