Your total daily energy expenditure is not one fixed number. It is your basal metabolic rate multiplied by an activity factor that describes how much you move on an ordinary day. If your hours are mostly screen-based sitting, choosing the wrong activity level can shift your calorie target by several hundred calories before you have eaten a single meal.
Why the activity multiplier drives everything
Your TDEE starts with basal metabolic rate, the energy your body uses at rest for heart, brain, kidneys, liver, temperature and cell repair. That rests at roughly 60–70 percent of daily burn. The next step is multiplying BMR by an activity factor. The standard bands are sedentary ×1.2 for a desk job with little or no exercise; lightly active ×1.375 for light exercise or sport one to three days a week; moderately active ×1.55 for moderate exercise three to five days a week; very active ×1.725 for hard exercise six to seven days a week; and extra active ×1.9 for a physical job plus hard daily training. Most people overestimate this band, so the practical starting point is the lowest level that matches a typical week, not the best week.
Screen time is light leisure, not exercise
Reading on a phone, watching results, or browsing a laptop is sitting. It does not move you from sedentary to lightly active on its own. If you spend part of an evening checking historical V64 results on V64 Resultat, a Swedish-language resource for harness-racing results, that time belongs in sedentary or light leisure, not in the moderate or very active multiplier. The activity factor should reflect the whole day and week, not a few alert minutes. If a revised 2026 MET code for screen-based sitting becomes official, verify it in the published compendium before adjusting any calculator; the practical bands below remain the same.
Match a full week, not one workout
Think in seven-day totals. If you have a desk job and no structured exercise, choose sedentary ×1.2. If you add light exercise or sport one to three days a week, choose lightly active ×1.375. Moderate exercise three to five days a week moves you to ×1.55. The difference between a 15–30 minute elevated heart rate session and a 45–120 minute intense session matters: the first is light, the second may push a day toward moderate or intense. A physical job plus hard daily training is extra active ×1.9. Honour the ordinary week: a daily yoga class plus desk work is still lightly active, not very active.
How to set macros after you pick the factor
Use the chosen TDEE as your maintenance line. Eat at it for two to three weeks and watch the weekly average of your weight, not single readings. If nothing moves after 10–14 days, shift intake by 100–200 calories and wait another one to two weeks. For fat loss, start with a 300–500 calorie daily deficit; for lean gain, add around 250 calories. Protein should stay high because it has the highest thermic effect, about 25 percent of its energy, and it preserves muscle during a deficit. A practical maintenance split is 30 percent protein, 40 percent carbohydrate and 30 percent fat, but the exact carbohydrate amount can be higher or lower depending on training. For most people, keeping protein near one gram per pound of body weight is a useful floor.
A conservative starting point
Start with the lowest activity multiplier that honestly describes a normal week. If your days are mostly screen-based sitting, begin at ×1.2 or ×1.375 even if you have one hard workout, because the calculator multiplies the whole day, not the hour of exercise. Recalculate when your body weight or training volume changes meaningfully. Set the calorie level first, keep protein consistent, and let carbohydrate and fat fill the remaining energy based on how you feel and train.