What a Weight Loss Calculator Actually Measures
Weight loss calculators are not all the same — each type answers a different question about your journey. Here are the most commonly used, and what they show you:
Percentage Weight Loss
One of the most useful metrics on a GLP-1 journey, percentage weight loss expresses how much you have lost relative to your starting weight. The formula is straightforward: (weight lost ÷ starting weight) × 100. Tracking percentage rather than absolute kilograms is particularly helpful when comparing progress across different people or body sizes.
Calorie Deficit Calculator
A calorie deficit (or kcal deficit) calculator estimates how many fewer calories you are consuming than your body burns. Understanding your deficit can help explain the pace of weight change — a sustained moderate deficit typically underpins steady, gradual loss. These estimates are based on averages and are educational guides, not personal prescriptions; what works for your body may differ. You can explore how calories and weight loss interact in more detail, or use our dedicated calories and weight loss calculator to run the numbers.
BMR and TDEE
Your Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest. Total Daily Energy Expenditure (TDEE) layers in your activity level. These figures underpin most calorie-deficit and weight loss calculators. BMI (Body Mass Index) is another common reference point, though healthcare professionals increasingly consider it alongside other measures.
Weight Loss by Date
Some calculators let you set a target and project a date — or work backwards from a date to estimate the deficit required. These are useful for setting realistic expectations, though weight loss is rarely perfectly linear, especially on a GLP-1 medicine where appetite changes, dose adjustments, and natural plateaus all play a role.
For a broader view, see our weight loss calculator with calorie tracking, or try our free weight loss calculator to get started quickly. If you are also tracking on Wegovy, our Wegovy weight loss calculator is tailored to that journey.
average weekly weight change in the first 16 weeks of Mounjaro & Wegovy use*
Tracking the right four numbers — weight, waist, protein and dose — turns a noisy chart into a clear story. That's the loop GLP-1 users keep coming back for.
AI Meal Tracking. Built for GLP 1 Appetites.
Point your camera at any meal and let our AI do the rest. Breakfast, doses, weight, mood all tracked in seconds.
Tracking Your Numbers Automatically with GLP Trackr
Running calculations manually is useful once — but staying on top of your progress week after week is where most people lose momentum. GLP Trackr is built specifically for people on Mounjaro and Wegovy, and its weight and body tracking tools do the maths for you in real time.
Weight Charts and Weekly Transformation
Log your weight each day or whenever you weigh in, and GLP Trackr plots it into charts that show your trend over time — not just today's number. The weekly transformation view lets you see exactly how far you have come since you started, which is motivating on weeks when the scale barely moves.
Targets and Calorie Tracking
Set your calorie and protein targets, then log meals using the AI photo scan (point your camera at a plate and get an instant nutrition breakdown), barcode scan, or search. Your running calorie and macro totals update automatically — no spreadsheet needed. This feeds directly into understanding your real-world deficit, making the numbers from any weight loss calculator meaningful rather than theoretical.
Insights That Go Beyond the Scale
The app's analytics surface correlations between your habits — sleep, protein intake, steps — and your weight trend, and can flag a plateau before it feels discouraging. You can also export a summary to bring to your prescriber appointments, so your tracked data supports those conversations.
GLP Trackr is a tracking and journaling app — it supports your journey, but it does not replace your prescriber or doctor. If you have questions about your progress, targets, or how your medicine is working for you, always discuss them with your healthcare professional.
Find all our tracking tools in one place at the calorie calculator hub.
Ready to turn your weight loss calculations into a living record of your journey? Download GLP Trackr on the App Store or Google Play and start your free 7-day trial today.
What does glptrackr include?
10+ powerful features. One app. Built specifically for Mounjaro and Wegovy users.
Everything your GLP-1 journey needs. Free to try for 7 days.
Morning Check-In
Start every day with a 60-second wellness check-in. Log how you're feeling, track nausea, appetite, energy, and mood — giving you and your care team a complete picture of how your medication is working.
Injection Tracking
Log every dose with a single tap. Track your dose history, phase in your cycle, estimated medication levels, and upcoming injection dates — with reminders so you never miss a scheduled shot.
Hydration Reminders
Staying hydrated is especially important on GLP-1 medications. Set daily water targets, log intake throughout the day, and receive smart nudges when you're falling behind your goal.
Smart Meal Planning
Personalized meal plans built around your current dose phase and side effects. Every meal is GLP-1 optimized — high in protein, gentle on the stomach, and scaled to your reduced appetite.
Recipe Library
Browse 50+ high-protein, GLP-1-friendly recipes filtered by meal type, prep time, and dietary needs. Every recipe includes full nutrition info, step-by-step instructions, and tips for eating with side effects.
Progress Analytics
Beautiful, easy-to-read charts show your weight loss trajectory, weekly nutrition trends, medication responses, and wellbeing scores over time — turning raw data into genuine insights.
AI Meal Scanning
Snap a photo of any meal and get a full nutrition breakdown in seconds — calories, protein, carbs, fat, and fibre. No searching. No manual logging. Just point, snap, and track.
Exercise & Steps
Log walks, workouts, and movement with activity targets that flex with your energy levels. On lower-energy dose days, gentler targets keep you moving without burning out.
Community Support
Connect with thousands of others navigating the same medication journey. Share milestones, ask questions, find accountability partners, and get support from people who truly understand.
Never Forget a Dose Again.
Log your Mounjaro or Wegovy injection in seconds. Track your pen, your dose level, and your injection site — so you always know exactly where you are in your treatment.
Watch Your Body Transform, Week by Week.
Log your weight, measurements, and how you're feeling after each dose. GLPTrackr turns your data into clear, motivating charts that show you how far you've really come.
You're Not on This Journey Alone.
Connect with thousands of real GLP-1 users sharing their wins, side effect tips, and meal ideas. Get the support of people who truly get it — because they're living it too.
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The Most Advanced GLP-1 Brain Ever Built.
The first AI built exclusively for GLP-1 weight loss. Every insight, every meal plan, every prediction trained on one thing only: helping you get the most out of your medication.
Knows Your Cycle
GLPIQ tracks where you are in your injection cycle and adjusts everything around it: lighter meals on nausea days, higher protein when appetite returns, and smarter targets as your medication level shifts.
Predicts Before You Feel It
GLPIQ learns your personal side effect patterns over time. After a few cycles, it starts warning you the morning before a rough day — and adjusts your meal plan automatically.
Finds Your Golden Dose
GLPIQ analyses every dose you've been on: weight loss rate, side effects, food noise, mood, protein adherence and tells you which dose gave you the best results. No other app does this.
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Frequently asked questions.
Divide the total weight you have lost by your starting weight, then multiply by 100. For example, losing 8 kg from a starting weight of 100 kg gives 8% weight loss. GLP Trackr calculates and charts this for you automatically as you log your weight.
A calorie deficit means consuming fewer calories than your body burns in a day. Over time, a sustained moderate deficit typically leads to gradual weight loss. The size of the deficit needed varies between individuals — your prescriber or a registered dietitian can help you identify a suitable target for your situation.
Yes — the same percentage loss, deficit, and BMI calculations apply whether you are on Mounjaro (tirzepatide) or any other medicine. GLP Trackr is built specifically for Mounjaro and Wegovy users, letting you track weight alongside doses, food, and side effects in one place.
No — they measure different things. A weight loss calculator tracks how much weight you have lost (often as a percentage or in relation to a calorie deficit), while a BMI calculator estimates body mass relative to height. Both are useful reference points, though neither replaces a full health assessment by your healthcare professional.
Online calculators use population-average formulas, so results are estimates rather than precise personal predictions. Individual factors — metabolism, activity, muscle mass, and how your body responds to a GLP-1 medicine — all affect real-world results. Use them as useful guides, and discuss specific goals with your prescriber or doctor.