Sources and method

1. The model never gives a meal’s total

For a photo or a described meal, the analysis model identifies the foods, estimates the weight of each in grams and suggests its makeup per 100 g — energy, protein, carbohydrates, fat. It never states the total for a plate.

Your phone does the rest:

it checks that each per-100 g value is physically possible (no more than 900 kcal, and no more than 100 g of any macronutrient, per 100 g) and consistent with the energy its macronutrients provide (Atwater factors);
it multiplies each value by the estimated weight;
the meal’s total is the sum of those rows.

A food you search for by name, or a saved food, takes its values from the Ciqual table; a product scanned by its barcode, from Open Food Facts. Every meal in the app shows which of these paths produced its numbers.

What stays uncertain is the identification, the weight and, for a photo or a description, the estimated makeup. A photo can’t show what’s in a sauce, or the oil a pan-fried dish has already soaked up: mixed dishes and added fats are the hardest cases, and that’s where the gap widens.

Every food and every quantity can still be changed after the analysis. A correction is saved exactly as you enter it, and the total is recalculated.

2. Where each number comes from

The number shown	Its source	Published by
Calories and macros for a food you search by name	Ciqual 2025 French food composition table	ANSES, the French Agency for Food, Environmental and Occupational Health & Safety
Packaged foods, by barcode	Open Food Facts	Open, collaborative database
Your daily calorie goal	Mifflin-St Jeor equation	Dietary Reference Intakes, Institute of Medicine, 2005
Your BMI and the range it falls in	Body mass index classification	World Health Organization

The same references are available in the app, next to the numbers themselves: under the daily goal, on a meal’s screen, on the BMI screen, and in Settings → Legal and data.

3. How your daily goal is worked out

Your calorie goal isn’t picked at random, and it isn’t up for negotiation: it’s calculated from what you entered, with a published formula, and the same profile always gives the same result.

Step 1: basal metabolic rate

The Mifflin-St Jeor equation, for the energy you use at rest over a day:

(10 × weight in kg) + (6.25 × height in cm) − (5 × age) + constant

The constant depends on the sex you entered: + 5 for a man, − 161 for a woman, and − 78, halfway between the two, when the question wasn’t answered. Refusing to go any further because a box wasn’t ticked would be a bad trade; the difference it makes is small, and it’s written down here.

Step 2: activity level

The result is multiplied by a factor based on how many workouts you do:

0 to 2 workouts a week: × 1.375
3 to 5 workouts a week: × 1.55
6 or more workouts a week: × 1.725

Until you set this level in Settings → Personal details, the middle factor, × 1.55, applies. It’s an estimate, and we say so: with no information, the middle value is the one least likely to be far off.

Step 3: your goal

Lose weight: × 0.8
Maintain your weight: × 1
Gain weight: × 1.1

A percentage rather than a fixed number of calories taken off: the same cut would be harsh for a small person and hardly noticeable for someone larger.

Step 4: the floor

The result never goes below 1,500 kcal for a man and 1,200 kcal otherwise. When this floor kicks in, the app tells you on screen rather than quietly showing the corrected number.

Step 5: splitting it into macronutrients

The energy is split into 55% carbohydrates, 18% protein and 27% fat, then converted to grams at 4 kcal per gram of carbohydrate or protein and 9 kcal per gram of fat.

The same calculation, worked through

A 32-year-old woman, 165 cm, 68 kg, doing 3 to 5 workouts a week, who wants to lose weight:

Basal metabolic rate	(10 × 68) + (6.25 × 165) − (5 × 32) − 161 = 1,390.25 kcal
With activity	1,390.25 × 1.55 = 2,154.89 kcal
With the goal	2,154.89 × 0.8 = 1,723.91, rounded to 1,724 kcal. The 1,200 kcal floor isn’t reached, so it doesn’t apply.
In macronutrients	237 g carbohydrates, 78 g protein, 52 g fat

You can replace this goal with your own at any time. A value you’ve entered by hand is never silently overwritten: if a weigh-in or a change to your profile changes the calculation, the app asks before taking over again.

4. Body mass index

The BMI shown in the Progress tab is your weight divided by the square of your height in meters. The ranges used to place it are the World Health Organization’s:

Underweight	BMI below 18.5
Normal weight	BMI 18.5 to 25
Overweight	BMI 25 to 30
Obesity	BMI 30 and over

These ranges are a statistical classification, not a diagnosis. They describe a zone on a scale, they say nothing about your health, and the app draws no recommendation from them. BMI doesn’t tell muscle from fat, and for some body types it stops meaning anything at all.

5. What these numbers are not

CalSnap is a food tracking tool. It helps you log what you eat and compare it with a goal you set.

It isn’t a medical device and doesn’t give medical advice. The values shown are estimates: they come from identifying foods in a photo and from public food composition tables, not from measuring what you actually ate.

Before making lasting changes to what you eat, talk to a doctor or a dietitian, especially if you’re under a doctor’s care, pregnant or under 18.

6. Data licenses

The tables used are public, and they stay that way: ANSES’s Ciqual table is published under the Licence Ouverte / Etalab 2.0 (the French government’s Open License), and the Open Food Facts database under the Open Database License (ODbL). CalSnap uses them in line with these licenses and claims no ownership of them. The version of the table built into the app is shown in Settings → Legal and data.

7. Spotted a mistake on this page?

If a number looks wrong to you, or a source has been updated on its end, write to support@calsnap.fr. It’s a useful correction, not a bother.

See also: the privacy policy for what happens to your data, and the terms and conditions for what the app commits to.