GLP-1 medications such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) are highly effective, and this post is not intended to discourage their use. It is intended to make sure you start them with the right expectations and a plan. These are the five things I discuss with every patient before prescribing.
1. They are not a magical quick fix for lasting weight loss
People can regain weight rapidly after ceasing GLP-1 medications. To prevent this, GLP-1s need to be considered a tool to change long-term underlying dietary habits and build a positive, healthy relationship with food and eating. If you are starting a GLP-1 for weight management, you need to be prepared to change underlying dietary habits and to consider how long you would be prepared to be on it. They can be used safely long term, but financially this is a big commitment.
2. Resistance training and adequate protein are critical
Independent of how or whether a GLP-1 is used, when weight loss occurs, usually 25–40% of it is lean mass. If someone regains that weight, it is mainly fat mass, and metabolic health can end up worse than before the initial weight loss. The same principle applies to meal replacement diets.
Resistance training and adequate protein (around 1.2 grams per kilogram per day) are critical to prevent muscle atrophy, and regular resistance exercise also has strong evidence for preventing weight regain. With rare exceptions, being prepared to do regular resistance training is one of my prerequisites for prescribing a GLP-1, and I often refer to an exercise physiologist.
3. Do not stop them suddenly
This is especially important on a higher dose (above 5 mg of tirzepatide). The data – and what I see clinically – shows that if the GLP-1 is weaned very gradually, the patient is more likely to maintain their weight loss.
I do a lot of pre-pregnancy metabolic health optimisation, and we wean very slowly before trying to conceive. Sudden GLP-1 cessation prior to pregnancy is associated with higher early-pregnancy weight gain, which can increase the risk of a range of complications.
4. You do not automatically need to increase the dose
You do not need to step up from 2.5 mg to 5 mg weekly just because that is the schedule on the packaging. That is drug company marketing. Use the lowest dose that achieves the required therapeutic goal.
5. Tell your anaesthetist before any procedure with sedation
GLP-1s slow gastric emptying, which can leave food in the stomach and risk aspiration and other anaesthetic complications. Australian guidance on whether to withhold doses or fast on clear fluids before a procedure has been updated recently, so make sure your anaesthetist knows you are on a GLP-1 and follow their specific instructions.