Weight gain
Calorie counting isn’t only for eating less. If you want to gain weight, or build up while you train, knowing how much to eat each day beats guessing. Choose “Gain weight” as your goal, and Calorix sets daily calorie and protein targets for a steady gain.
How Calorix sets a weight-gain target
- Your resting energy (BMR). Calorix estimates the energy your body uses at rest with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women (if you choose “other”, Calorix uses the midpoint, minus 78).
- Your maintenance calories (TDEE). It multiplies your BMR by an activity factor, from 1.2 (sedentary) to 1.9 (very active).
- The surplus. Using about 7,700 kcal per kilogram of body weight, it adds what your weekly pace needs: about 275 kcal a day at 0.25 kg (0.55 lb) a week.
- The safety rails. The pace can’t go above 1% of your body weight a week, and the result is rounded to the nearest 10 kcal.
For example, take a 25-year-old man who is 175 cm (5 ft 9 in) tall, weighs 60 kg (132 lb), is moderately active and wants to reach 65 kg (143 lb) at 0.25 kg a week. His BMR is about 1,574 kcal and his maintenance about 2,439 kcal, so Calorix sets 2,710 kcal a day, with 104 g of protein, 90 g of fat and 370 g of carbs, and projects 140 days to his goal. If he slides the pace to its maximum, 0.6 kg (about 1.3 lb) a week, which is 1% of his weight, the target becomes 3,100 kcal and the app tells him that pace is ambitious, because it’s above 0.75% of his weight.
Try your own numbers with the free TDEE calculator, and read how Calorix calculates your calorie target for the full method.
Why a slow surplus works better
Gaining too fast means eating a lot more overnight, which makes every meal a chore and is hard to keep up. That’s why Calorix starts at a modest 0.25 kg a week and caps the pace at 1% of your body weight. Your weight also responds to a change in eating slowly, as your body adapts (Hall et al., 2011), so treat the projected date as a guide, not a deadline.
Day-to-day weight jumps with water and food. Calorix turns your weigh-ins into a trend line, so you can see whether you’re gaining without reacting to every reading.
Protein and macros
For a gain goal, protein is set at 1.6 g per kg of your goal weight (in the example, 65 kg × 1.6 = 104 g), capped at 2.2 g per kg of your current weight and at 35% of your daily calories. By default, fat is 30% of your calories and carbs make up the rest, and you get fiber and water targets too.
If you train, spreading protein over your meals also makes it easier to log. Follow all three macros with the macro tracker, or just protein with the protein tracker.
Logging bigger meals quickly
Eating more means more to log, and logging that feels like work doesn’t last. Calorix is built to keep it quick:
- Photo logging. The AI calorie scanner lists each ingredient with its grams, so a big plate or a second helping only needs a portion tweak.
- Barcodes and labels. Protein shakes and packaged snacks log with the numbers printed on the package.
- Recent foods and favorites. Your daily snack or shake goes back in with one tap.
- Voice and text. Say “two eggs, toast and a banana” and it’s logged.
Toasty is on your side
Toasty, Calorix’s ember mascot, eats with you when you log a meal and cheers when you reach your goals. Toasty never sorts food into good or bad and never comments on your body or your weight, whichever direction you’re going. Keep your streak and Toasty glows brighter; take a break and Toasty simply waits for you to come back.
When to talk to a professional first
Calorix gives general wellness estimates, not medical advice. If you’re underweight, have lost weight without trying, live with a medical condition, are pregnant or breastfeeding, are under 18, or have a history of disordered eating, talk to a doctor or a registered dietitian before you set a goal.
Updated October 23, 2026
