The first four weeks: what actually happens
The start is the most unpleasant phase, and the one where most people stop. What is typical in the first four weeks, what helps, and when to call your doctor.
- Treatment course
Quick answer
Every GLP-1 treatment begins at the lowest dose and is only increased after at least four weeks. That starting dose is not meant to reduce weight; it is there to establish how well you tolerate the medicine.
The most common complaints are nausea, constipation and feeling full after a few bites. Unpleasant, but usually temporary. What is not temporary, and needs checking straight away, is set out below.
What happens in the body
Gastric emptying slows and the fullness signal arrives earlier. That is why half a portion is suddenly enough — and why too much food at once sits heavily.
The often-described effect of constant thoughts about food getting quieter appears in the first weeks for many people. It is not a guarantee and not a measure of response.
What the first weeks are about
The first four weeks are about tolerability, not kilos. Watching the scale in this phase measures the wrong thing.
At the end of the first step, your doctor decides on the basis of tolerability and progress whether the dose increases. How long you have been on a step is the key piece of information for that.
Side effects in the starting phase
These complaints are common in the starting phase. They tend to be more noticeable in the days after a dose increase.
- Nausea, particularly in the first days on a new dose
- Constipation or diarrhoea
- Fullness after small portions, reflux, burping
- Tiredness and headaches, often from drinking too little
- Seek medical advice immediately: severe upper abdominal pain radiating to the back, persistent vomiting, worsening vision
Frequently asked questions
Sources and medical review
Based on European Medicines Agency product information and the manufacturers' prescribing information. This article is educational and does not replace individual medical advice. For acute symptoms contact your doctor, the out-of-hours service on 116 117, or 112 in an emergency.
- European Medicines Agency product information
- Manufacturers' prescribing information