How Does Weight Loss Work on a GLP-1 Weight Loss Jab?

Semaglutide (the active substance in Wegovy) works by mimicking GLP-1, a natural hormone released after eating. This slows the rate at which the stomach empties, signals fullness to the brain, and reduces what many people describe as constant background thoughts about food — sometimes called "food noise." Tirzepatide (the active substance in Mounjaro) targets both GLP-1 and a second hormone pathway, GIP, which together influence appetite and how the body processes energy.

The result, for many people, is that eating less starts to feel natural rather than forced. Portions that once felt too small become satisfying. Cravings that previously felt relentless can ease. Over time, this consistent reduction in energy intake leads to the body drawing on its stored fat for fuel — which is how weight loss occurs.

Why progress isn't always a straight line

Even when everything is going well, weight loss on these medicines is rarely a smooth downward slope. Several factors shape the pattern:

• Water and glycogen shifts — early changes on the scale often reflect fluid changes as much as fat loss.
• Dose stages — titration periods, where the dose is increased gradually by your prescriber, can influence how appetite suppression feels from week to week.
• Plateaus — the body adapts over time, and periods of slower progress are common and normal. They don't mean the medicine has stopped working.
• Individual variation — factors like sleep, stress, protein intake, and activity levels all interact with how your body responds.

It's also worth knowing that weight loss is only part of what many people track on this journey. Energy levels, mood, how clothes fit, and side-effect patterns all form a fuller picture of progress. For a broader look at the journey, the weight loss tracking guide covers these dimensions in more depth.

Some people also explore complementary approaches alongside their prescribed treatment — for example, there's growing interest in berberine and its relationship to weight loss, though any additions to your routine should be discussed with your prescriber or doctor first.

It's also worth noting that weight change can have knock-on effects elsewhere in the body — research into whether weight loss reduces cholesterol is one area many people find relevant to their broader health picture.

Understanding how weight loss works is one thing — seeing your own pattern unfold is another. GLP Trackr's weight and progress tracking lets you log your weight regularly and watch your trend emerge over time, with charts that smooth out the day-to-day noise so you can see genuine direction rather than fixating on single readings.

The weekly transformation view captures more than just the number on the scale — you can log measurements, mood, energy, sleep quality, and food-noise levels in a quick daily check-in, giving you a richer record of how you're actually feeling as the weeks progress. When a plateau arrives (and for most people, it will at some point), having a detailed log helps you and your prescriber identify what might be influencing it — whether that's protein intake, sleep, or activity.

The insights and correlation features go a step further, surfacing patterns in your own data: for instance, whether the weeks you hit your protein target tend to coincide with stronger progress on the scale. That kind of personalised picture is hard to see without consistent tracking.

If you're also curious about supplement-based approaches some people use alongside their programme, it may be worth reading about weight loss products at Holland and Barrett — though always check with your prescriber before adding anything new.

GLP Trackr is available free on the App Store and Google Play, with a 7-day free trial — start logging your progress today and let the data tell your story.

Every person's response to these medicines is different. If you have questions about your progress, a plateau, or how your treatment is going, your prescriber or doctor is the right person to ask — they know your full history and can give guidance tailored to you.