Short answer: With GLP-1 weight-loss injections, appetite may change in the first days after the first injection. Weight loss is gradual: the starting dose is for tolerability, not for weight loss, so look at your weight trend over several weeks rather than single weigh-ins.

Key takeaways

  • Appetite may change in the first days after the first injection.
  • The starting dose is for tolerability, not for weight loss, so the scale may not move much in the first weeks.
  • Weight loss is gradual; the trend over weeks matters more than any single weigh-in.
  • Haftra's Goal Weight Forecast calculates the weekly trend from at least 4 weeks of entries and shows a target date when there is enough data.

Two separate questions get mixed up: when the medication starts working, and when change shows up on the scale. The first is usually felt in the first days; the second is a curve that takes weeks and may not be noticeable at the starting dose.

This page is for general information only and promises no personal result. Responses vary from person to person; only your doctor can assess how your treatment is going.

What do you feel in the first days?

These medications slow stomach emptying and prolong the feeling of fullness. Pharmacologically, this effect begins after the first injection; you may notice in the first days that you get full sooner and your portions get smaller.

The same mechanism is also the source of side effects: nausea, bloating and constipation stand out most in the first days and after each dose increase.

When does weight change?

The starting dose is usually not a therapeutic dose; its purpose is to get the body used to the medication. That is why there may be no clear movement on the scale in the first weeks. As the dose steps go up, the effect becomes more noticeable.

The weight curve does not go down in a straight line. Daily fluctuations are related to fluid, salt, sleep and bowel movements, and they get confused with the medication's effect. The only meaningful indicator is the trend over weeks, not the difference between two weigh-ins.

What if it feels like it is not working?

In the early weeks, this is a common impression and is often related to the dose step. Only your doctor decides what to do (wait on the current step, increase the dose or review the treatment). Increasing the dose on your own increases side effects; it does not speed up the process.

Having dated records with you at a follow-up visit makes this assessment easier: how long you stayed on each step, how your weight moved, which side effect happened on which day.

Seeing the trend

Haftra applies a trend to your weight entries and shows the direction instead of daily fluctuation. If there is not enough data, or no clear decrease, it does not show an estimated date. It does not substitute a clinical trial average for your own result. It is free and can be used without an account.

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Frequently asked questions

When do weight-loss injections start working?

The effect that slows stomach emptying and prolongs the feeling of fullness begins after the first injection; appetite may change in the first days, and you may notice that you get full sooner and your portions get smaller. Weight loss itself is gradual.

When does weight start to change?

The starting dose is usually not a therapeutic dose; it is meant to build tolerance, so there may be no clear movement on the scale in the first weeks. As the dose steps go up, the effect becomes more noticeable, and the body's response varies from person to person.

What should I do if it feels like it is not working?

In the early weeks, this is a common impression and is often related to the dose step. Only your doctor decides what to do. Increasing the dose on your own increases side effects; it does not speed up the process.

Should I weigh myself every day?

Daily fluctuations are related to fluid, salt, sleep and bowel movements, and they get confused with the medication's effect. The only meaningful indicator is the trend over weeks, not the difference between two weigh-ins.

How much average weekly weight loss is healthy?

The rate differs from person to person and slows over time; weight loss is gradual. What pace suits you is for your prescriber to judge.

When does weight loss pause (plateau)?

Weight loss usually slows over time and can level off. What to do then, such as staying on the current dose, changing the dose or reviewing eating habits, is your doctor's decision.

Sources

  • EMA - Mounjaro (tirzepatide)
  • EMA - Ozempic (semaglutide)
  • EMA - Wegovy (semaglutide)
  • NHS - Obesity treatment
  • U.S. Food and Drug Administration (FDA)

Last reviewed: August 4, 2026