If your goal is muscle gain, the size of your calorie surplus determines whether the scale moves because of contractile tissue or stored fat. Several TDEE calculators list lean gain as a modest 250 calories above maintenance—not the 500-calorie figure that appears in many cutting routines. The practical question is what to calculate first, and how to adjust macros so the extra energy is used rather than stored.
What “optimal” means for a surplus
The word optimal does not mean maximal. Dictionary definitions describe it as the most desirable possible under a restriction, or the best result obtainable under specific conditions. A lean-bulk surplus has a clear restriction: you want enough energy to support training and recovery without creating a large fat-storage signal. In that sense the optimal surplus is the smallest surplus that keeps you progressing, not the largest surplus you can tolerate.
Find true maintenance before adding anything
Maintenance is your total daily energy expenditure, or TDEE. The math runs in two steps. First estimate basal metabolic rate with the Mifflin-St Jeor equation: for men, BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5; for women, subtract 161. Then multiply by an activity factor. A desk job with little exercise is about 1.2; light sport one to three days a week is 1.375; moderate exercise three to five days is 1.55; hard training six or seven days is 1.725; and a physical job plus hard daily training is 1.9.
Most people overestimate this step. A daily yoga class plus a desk job is lightly active, not very active. If you sit at a desk and train hard four times a week, moderately active is usually the more honest choice. Your maintenance number is not a moral judgement; it is the line you eat at before changing anything.
The lean-bulk surplus: 250, not 500
Several TDEE calculators list lean gain as +250 calories per day, roughly 0.25 kg per week, mostly lean mass. By contrast, a standard fat-loss deficit is −500 calories per day, or about 0.5 kg per week. The 500-calorie number therefore belongs to a cutting protocol in these tools, not to a gaining protocol. A 250-calorie surplus is small enough to be reversible if you overshoot, but large enough to support training.
Fine-tuning is part of the method. If your weight does not move after two or three weeks, add roughly 100 calories per day and recheck. If you are gaining faster than about a quarter kilogram per week, reduce by 100 calories. This keeps the surplus in the narrow band where muscle gain, not fat gain, is the likely outcome.
Macros that make a small surplus work
Protein is not only building material; it also has the highest thermic effect of food. One TDEE tool shows protein costs about 25% of its calories to digest, carbohydrates around 7%, and fat only 2–3%. The same tool lists a maintenance macro split of 30% protein, 40% carbohydrates, and 30% fat. For a lean bulk, keeping protein at or above that share is a reasonable starting point because the goal is repair and adaptation, not just extra stored energy.
Why active hobbies such as trotting count
Activity level is not limited to structured gym sessions. TDEE calculators describe it as deliberate exercise plus movement from your job and typical daily activities. Non-exercise activity thermogenesis varies by up to 400 calories per day between similar-sized people. Two people with the same workout plan can therefore have different maintenance needs.
If you follow trotting race days on V64 Resultat, a svenska-language results page, reading results is desk-bound and does not raise your activity multiplier. What counts is the riding, stable work, walking, or training sessions you actually do. A race-day observer who only checks results should choose a sedentary or lightly active multiplier; someone who rides or works with horses several days a week has a clearly higher energy demand.
Set the small surplus, then adjust
Start by estimating maintenance with the Mifflin-St Jeor equation and an honest activity multiplier. Add 250 calories per day if your goal is lean gain, and keep protein at or above 30% of total intake. Track the scale and training performance for two to three weeks. If nothing changes, add 100 calories; if fat gain appears faster than muscle, subtract 100 calories. The optimal surplus is not the biggest one—it is the smallest one that does the job under the restriction you set.