A calorie is a unit of energy. Your body needs energy (calories) to do everything — breathe, think, walk, digest food, even sleep.

Food gives you calories. Movement burns them. If you eat more than you burn, the extra gets stored as fat. If you eat less than you burn, your body uses stored fat for energy — and you lose weight.

BMR stands for Basal Metabolic Rate. It's the number of calories your body burns just to stay alive — even if you lay in bed all day and did nothing.

Your heart beating, lungs breathing, brain thinking, liver working — all of that uses energy. That's your BMR.

For most people it's between 1,200–1,800 kcal per day depending on your size, age and sex.

TDEE stands for Total Daily Energy Expenditure. It's your BMR plus all the extra calories you burn through daily movement and exercise.

If you eat exactly your TDEE every day, your weight stays the same. Eat less = lose weight. Eat more = gain weight.

This app calculates your TDEE using a formula called Mifflin-St Jeor — the same one used by MyFitnessPal and most professional dietitians.

It uses your height, weight, age, sex and activity level to estimate how many calories you burn each day.

When you picked your activity level (Mostly Sitting, Lightly Active etc.), that told the app roughly how much you move. It multiplies your BMR by a factor based on that choice.

This estimate is about 85–90% accurate for most people — good enough for tracking purposes. When you log exercise in the diary, that gets added on top.

Macros (macronutrients) are the three main nutrients that make up all food:

🥩 Protein (4 kcal per gram) — builds and repairs muscle, keeps you full. Found in meat, eggs, dairy, beans, tofu.

🍞 Carbohydrates (4 kcal per gram) — your body's main energy source. Found in bread, pasta, rice, fruit, veg.

🧈 Fats (9 kcal per gram) — essential for hormones and brain health. Found in oils, nuts, avocado, meat, dairy.

All three are important. None are "bad" — it's the total balance and quantity that matters.

Not all fat is the same. This app splits fats into two types:

🔴 Saturated fat (bad fat) — raises LDL (bad) cholesterol. Found in butter, red meat, cheese, pastries, fried food. Limit to under 20g/day (10g if your goal is lower cholesterol).

🟢 Unsaturated fat (good fat) — raises HDL (good) cholesterol, reduces inflammation. Found in avocado, olive oil, nuts, seeds, oily fish.

So 36g of fat from eggs and avocado is much better than 36g from butter and crisps — even though the calorie count is the same!

The AI uses average values for typical portion sizes. For most common foods it's within 10–15% of the actual value.

It's most accurate for simple meals (eggs on toast, chicken and rice) and less accurate for complex restaurant dishes or very specific recipes.

For best results: describe your meal as specifically as you can, including rough quantities ("2 large eggs", "big bowl of pasta"). You can always edit the numbers before saving.

Perfect accuracy isn't the goal — consistent tracking is. Being 90% right every day beats being 100% right once a week.

The app tracks 8 glasses (2 litres) as a daily goal — this is the standard NHS recommendation for adults.

You may need more if you exercise, it's hot, or you drink a lot of coffee (caffeine is dehydrating).

Signs you're not drinking enough: headaches, dark yellow urine, feeling tired or hungry when you've eaten enough.

Tip: drink a glass of water before each meal. It reduces appetite and helps with portion control.

A few common reasons:

📏 Inaccurate logging — cooking oils, sauces, drinks and "small bites" are often forgotten. They add up fast.

💧 Water retention — stress, salt, hormones and starting exercise can all cause you to hold water temporarily. The fat loss is still happening.

🏋️ Building muscle — if you've started exercising, muscle weighs more than fat. Your body composition may be improving even if the scale isn't moving.

📉 Metabolic adaptation — after several weeks, your body adjusts. Try taking a 1–2 week diet break at maintenance then restart.

Weigh yourself at the same time each morning (after the bathroom, before eating) and look at the weekly average rather than daily fluctuations.

When you scan a product's barcode, Lurie gives it a health score out of 100. It starts from the product's official Nutri-Score where available, then fine-tunes based on sugar, salt, saturated fat, additives and how processed it is. The score is colour-coded so you can decide at a glance.

⚠️ What lowers a score:

High sugar (over 12g/100g), high saturated fat (over 5g), high salt (over 0.6g), artificial additives, being ultra-processed, and being calorie-dense (over 350 kcal/100g).

✓ What raises a score:

High fibre (3g+), high protein (6g+), low sugar/salt/saturated fat, no additives, and organic certification.

Nutri-Score: where available, we also show the official European Nutri-Score (A–E). A is healthiest, E is least healthy. Lurie uses this as the starting point for its own score.

Lurie's rating uses public Open Food Facts data and established nutrition standards. It's a helpful guide, not medical or dietary advice.

Yes. Your food logs, metrics and goals are only visible to you. The app uses secure per-user access rules — even someone with database access cannot see another user's data.

Your data is stored securely in Firebase (Google's professional database platform) and never sold or shared with third parties.