How to Calculate Weight Loss: Percentages, Calories and Macros

Weight loss percentage

Percentage weight lost is one of the most commonly used measures in clinical and personal tracking. The formula is straightforward:

• Weight loss % = (weight lost ÷ starting weight) × 100

For example, if your starting weight was 100 kg and you have lost 8 kg, your weight loss percentage is 8%. This figure puts your progress in proportion to your starting point, which is more meaningful than a raw number alone. You can use the weight loss percentage calculator on this site to work it out instantly.

Calorie deficit and how to calculate weight loss calories

A calorie deficit — consuming fewer calories than your body uses — is the underlying mechanism behind fat loss. On a GLP-1 medicine, many people naturally eat less because appetite and food noise reduce, which often creates a deficit without deliberate restriction. Understanding roughly how many calories your body needs is still useful context.

A general starting point is to estimate your total daily energy expenditure (TDEE) — the calories your body burns across the day — and then establish a moderate deficit from there. For educational context, a deficit of around 500 calories per day is often cited in general guidance as supporting gradual loss, though the right figure for any individual depends on many personal factors. For a step-by-step approach to this, see how to calculate your daily calories and how to calculate a calorie deficit.

How to calculate macronutrients for weight loss

Macronutrients — protein, carbohydrates and fat — make up the calorie total, but their ratio matters independently of calories. On a GLP-1 journey, protein is particularly important: it supports muscle retention during weight loss and tends to be more satiating, which complements the appetite effects many people experience on these medicines.

A common educational approach is to set a protein target first (often expressed as grams per kilogram of body weight), then distribute remaining calories across carbohydrates and fat according to personal preference and tolerance. For a full walkthrough, visit how to calculate your macros. All of these calculations sit within the broader framework covered in the GLP-1 calorie calculator hub.

Working out these numbers manually is a useful exercise once — but doing it every day is where most people lose consistency. GLP Trackr's food logging feature takes the friction out of it: use the AI photo scan to point your camera at a meal and get an instant breakdown of calories, protein, carbohydrates and fat, or search manually and scan barcodes for packaged foods.

Once your targets are set inside the app — calories, protein, fibre, water — every meal you log feeds directly into your daily totals, so you can see at a glance whether you are on track without doing any arithmetic yourself. The insights dashboard then surfaces patterns over time: how your nutrition relates to your weight trend, where your protein tends to dip, and what a typical week actually looks like versus your targets.

All of that data builds a picture you can bring to your next appointment. Your prescriber or doctor can see how your eating patterns have shifted alongside your weight changes — which makes for a much more informed conversation than a number on a scale.

GLP Trackr is built specifically for people on Mounjaro and Wegovy, so the meal plans and recipe library are designed around the smaller, protein-forward eating patterns that tend to work well with these medicines — not generic diet advice.

The targets and calculations in GLP Trackr are general educational tools. For personalised guidance on your calorie or macro intake, always talk with your prescriber or a registered dietitian who knows your full health picture.

Ready to stop doing the maths by hand? Download GLP Trackr on the App Store or Google Play and start a free 7-day trial — your nutrition tracking is waiting.