How we calculate
Snacklet is for general wellness. It is not medical advice and does not diagnose or treat any condition. Talk to your doctor before changing how you eat or starting to fast, and especially if you are pregnant or breastfeeding, under 18, have or have had an eating disorder, or have diabetes or take medication that lowers blood sugar.
Your daily calories
We estimate the energy your body uses at rest with the Mifflin–St Jeor equation, from your weight, height, age and sex, then multiply it by how active a usual day is (from 1.2 for mostly sitting to 1.725 for very active).
For your pace we take away about 7,700 kcal for each kilogram you want to lose a week, spread over 7 days. The target never goes below 1,200 kcal a day (1,500 for men), and under 18 there is no deficit at all.
Until you add your height, sex, age and activity, we use a simpler estimate of about 28 kcal per kg of body weight. Either way it is a starting point: adjust it if your weight moves faster or slower than planned.
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Your goal date
The date is an estimate: it assumes you stay at your daily target every day. In real life weight loss slows down over time, because your body uses less energy as you get lighter, so it may take a little longer.
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Safe limits we keep
Paces go up to 0.75 kg a week, within the 0.5–1 kg a week usually advised.
A goal weight can’t go below a BMI of 18.5, the bottom of the healthy range. BMI is a rough guide: it doesn’t account for muscle, age or build.
Fasting coins stop at your goal, and past 24 hours the app suggests eating instead of cheering you on.
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Fasting stages
The stages are rough guides to what usually happens as a fast goes on: your last meal is digested, then your body draws more on stored energy, and later starts using more fat and making more ketones.
When this happens varies a lot from person to person. Research puts the switch to using fat somewhere between 12 and 36 hours, depending on your last meal, how active you are and your body.
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Photo and chat estimates
When you snap or describe a meal, an AI model identifies the foods and estimates the portion sizes.
The calories and macros then come from USDA FoodData Central, the US Department of Agriculture’s food composition database, wherever a matching food is found. When there is no match, or you tell us the calories yourself, we use the AI’s estimate or your number instead.
It’s still an estimate: portion sizes, oils and hidden ingredients can make it off. Check it before you log: pick the portion size that matches, and tell us if something looks wrong.
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Barcodes and labels
Packaged food comes from Open Food Facts, an open database built by volunteers. When a product isn’t there, the app reads its nutrition label from your photo.