You search "how many calories should I eat" and get fourteen calculators with fourteen different answers. None of them shows its work, so you pick the number you like best and three weeks later you cannot explain why nothing happened.
Let’s do it the other way around. Here is the whole method, the same one SinExcusas follows, so you can understand what you are looking at and argue with it.
Step 1: your basal metabolic rate
Your basal rate is what your body spends just existing: breathing, staying warm, beating. Without leaving the couch.
It is estimated with the Mifflin-St Jeor equation, which is what the app uses and what most nutrition guidance has recommended for decades, because it is the one that misses least in the general population:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women and everyone else: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
An example, so it stops being abstract. A 32-year-old man, 82 kg, 178 cm:
(10 × 82) + (6.25 × 178) − (5 × 32) + 5 = 820 + 1112.5 − 160 + 5 = 1777 kcal
That is what he would burn lying down all day. You can already see why eating 1200 kcal "because an app said so" is usually a bad idea.
Step 2: multiply by how much you move
An activity factor turns the basal rate into your total daily burn:
| Activity level | Factor |
|---|---|
| Sedentary | 1.2 |
| Light (1-2 days a week) | 1.375 |
| Moderate (3-4 days) | 1.55 |
| Active (5-6 days) | 1.725 |
| Very active (daily) | 1.9 |
Following the example, training four days a week: 1777 × 1.55 = 2754 kcal a day to maintain.
Here is the classic mistake: picking "very active" because you hit the gym five times. The factor covers your whole day, not just the hour under the bar. If you sit at a desk for eight hours and then train, you are moderate, not very active. Inflating this number is the most common way to eat more while believing you are in a deficit.
Step 3: subtract or add for your goal
SinExcusas does not use percentages. It uses a fixed calorie amount, which is easier to reason about, and lets you choose between three intensities: gentle, moderate and aggressive. Maintaining or toning gets no adjustment: you stay at your burn.
Our example, on a moderate deficit of 500 kcal, the classic reference: 2754 − 500 = 2254 kcal a day.
Which one to pick? Moderate is the sensible middle for most people. Aggressive is faster, harder to hold, and takes more muscle with it. Gentle is slow but barely noticeable, which is exactly why more people finish it.
Step 4: split the macros
With calories settled, they get split into three macronutrients. The order matters.
Protein first
Protein is set in grams per kilo of bodyweight, and depends on how much you move and what you are after. The literature puts the useful range between 1.6 and 2.4 g per kilo: higher the more you train and when you are in a deficit, lower at maintenance. The app picks the point in that range that fits you.
Our example, at 2 g per kilo: 82 × 2.0 = 164 g of protein, which is 656 kcal.
It goes up in a deficit on purpose. When you eat less, protein is what protects the muscle you spent years building, and what keeps you full on less food.
Fat: a percentage, not a whim
Fat is a share of total calories, somewhat lower in a deficit than at maintenance or in a surplus. That share is divided by 9, the calories in a gram of fat.
In the example, at 25 %: 2254 × 0.25 = 563 kcal ÷ 9 = 63 g of fat.
It drops in a deficit because the calories have to come from somewhere and protein is off limits. It does not drop to zero because your hormones and vitamin absorption depend on it.
Carbohydrates: whatever is left
Carbs are the remainder. Subtract the protein and fat calories, divide what is left by 4:
2254 − 656 (protein) − 563 (fat) = 1035 kcal ÷ 4 = 259 g of carbohydrates.
This is not carbs mattering less. They are the flexible lever: you raise them when training is hard and lower them when it is time to push, without touching what holds your muscle together.
The limits that stop something stupid
A loose calculation can spit out absurd numbers with extreme inputs. That is why the app applies safety caps to calories and to each macronutrient, and if the split leaves one outside its range, it corrects it before showing you anything.
If your result looks far too low or far too high, read it as a signal: you probably entered something wrong or picked an intensity that does not suit you.
The number is a starting point, not a verdict
Every formula is a population estimate. Your real metabolism can sit 10 % above or below it. The only way to find out is to measure.
The honest method:
- Eat your calculated number for two or three weeks, logging properly.
- Weigh yourself several mornings a week, under the same conditions, and keep the weekly average. A single day says nothing: water, salt and your gut move more than a kilo in 24 hours.
- Compare average against average. In a deficit, losing 0.5 % to 1 % of your bodyweight per week is a good pace.
- If nothing moves in three weeks, drop 200 kcal. If it drops too fast and you feel hollow, put them back.
That loop (calculate, execute, measure, adjust) is the entire job. Everything else is decoration.
What SinExcusas does for you
The app runs this whole calculation on your data and redoes it on its own when you log a new weight, edit your profile or change your goal. With those calories and macros it builds your week and splits the total across the meals you chose: anywhere from two to five a day, three by default.
What it cannot do for you is log. The math is the easy part; writing down what you eat for three straight weeks is what separates the people who progress from the people who go back to searching "how many calories should I eat".
This article is general nutrition and wellbeing information. It is not medical advice or an individual plan. If you have a health condition, are pregnant or breastfeeding, or are under treatment, talk to your doctor or a clinical dietitian before changing how you eat.
