The IDF-DAR Diabetes and Ramadan Practical Guidelines 2021 name three older GLP-1 medicines as examples, in people with diabetes, and do not mention tirzepatide or semaglutide (IDF-DAR). On the fast itself, MUIS cites the view of some scholars that medication given by injection does not invalidate it (MUIS). The labels for tirzepatide and semaglutide do not mention Ramadan, but they carry the rules a fasting month runs into: the dehydration warnings, and how late a dose can be given or its day moved. So the conversation to have with the doctor who prescribes it, at GetLean Dr Quek, is before Ramadan starts. This article sets out what each source says, and HPB's energy figures for the Hari Raya table.
In Singapore, tirzepatide is registered as Mounjaro, and semaglutide injection as Wegovy for weight management and as Ozempic for type 2 diabetes. The figures in this article are given by molecule, as the guideline and product labels report them. Whichever medicine is prescribed, GetLean plans the exit from the first consultation. Coming off GLP-1 in Singapore: what happens and how to plan sets out how.
Dose titration: stepping a medicine up to its working dose in stages. The US labels raise tirzepatide in 2.5 mg steps after at least 4 weeks on each dose, and semaglutide injection every 4 weeks (tirzepatide label, semaglutide label).
What the Ramadan guideline says about GLP-1 medication
IDF-DAR's recommendation on GLP-1 medicines names three of them: liraglutide, lixisenatide and exenatide. As long as these have been appropriately dose-titrated at least 2 to 4 weeks before Ramadan, it says, no further treatment changes are required (IDF-DAR).
The guideline is written for people with diabetes, as its title says. It describes GLP-1 medicines as reducing appetite and slowing the emptying of the stomach, with a low risk of severe hypoglycaemia when used alone and a possibly higher one alongside sulphonylureas or insulin (IDF-DAR).
On newer GLP-1 medicines, it says more research is needed, and the examples it gives are dulaglutide and albiglutide. Semaglutide and tirzepatide are not mentioned anywhere in the document (IDF-DAR).
Is there guidance for tirzepatide or semaglutide taken for weight?
The research on this group is thin. A 2023 review found "a dearth of studies focused specifically on the use of GLP-1 medications in nondiabetic patients during Ramadan" (Alayed 2023). A 2026 letter in the British Journal of Clinical Pharmacology is titled "Tirzepatide during Ramadan in people with obesity without diabetes: A critical knowledge gap" (Monjur 2026).
The same review recommends close monitoring and dose titration, "preferably at least four weeks before Ramadan" (Alayed 2023). That four weeks is the review's figure; the IDF-DAR text says at least 2 to 4 weeks, for its three named medicines.
One real-world study followed 109 adults with type 2 diabetes in Bangladesh who intended to fast and were prescribed tirzepatide at the 2.5 mg starting dose: mild digestive side effects occurred in about 12%, and no hypoglycaemia was reported (Rahman 2026). Those were people with diabetes, at the starting dose.
So applying the diabetes guidance to someone taking tirzepatide or semaglutide for weight is an extrapolation, and the decision belongs to the prescribing doctor.
Does a GLP-1 injection break the fast?
MUIS's answer is about injected medication in general, and it attributes the position to some scholars: "Based on the view of some scholars, medication administered through injection or intravenous method does not invalidate your fast as it does not go through an open orifice of the body. It is also not a type of food and drink that provides nourishment, nor does it satiate your hunger or thirst" (MUIS). The answer does not name any weight-loss medicine.
IDF-DAR says the same of insulin injections and blood glucose monitoring in people with diabetes: neither invalidates the fast (IDF-DAR).
Tablets are a separate question, and the labels do not settle it. The US label for oral semaglutide says to take it in the morning on an empty stomach with up to 4 ounces of water, then to wait at least 30 minutes before eating, drinking or taking other oral medicines (US label). The European label has no "in the morning"; it says to take the tablet on an empty stomach after a recommended fast of at least 8 hours, with a sip of water of up to 120 mL, and then to wait at least 30 minutes (EU label). Neither says the tablet may be taken at iftar, so when to take it in Ramadan is for the prescriber to decide.
Vomiting, dehydration and the fast
The labels warn that nausea, vomiting and diarrhoea can cause dehydration, and that dehydration can lead to kidney problems. Tirzepatide's US patient guide lists nausea, diarrhoea, decreased appetite, vomiting, constipation, indigestion and stomach pain among the most common side effects. It says "It is important for you to drink fluids to help reduce your chance of dehydration", and to tell your doctor right away about nausea, vomiting or diarrhoea that does not go away (US label).
The prescribing information records postmarketing reports of acute kidney injury, some needing dialysis, mostly in people whose digestive side effects had led to dehydration, and the US semaglutide label carries the same warning (tirzepatide, semaglutide). The European labels ask patients to take precautions to avoid fluid depletion (tirzepatide, semaglutide). That is the warning to plan around in a month of daytime fasting.
On the religious side, MUIS says involuntary vomiting does not invalidate the fast. If it happens because of sickness, MUIS says "you have to consider breaking your fast and make up for it on another day", because those who are unwell are not obligated to continue fasting (MUIS). For people who are unwell and in hospital, MUIS says to follow the advice of medical experts, in line with religious guidance that allows the unwell to fast on other days after Ramadan (MUIS).
What helps with nausea day to day is covered in managing nausea on GLP-1 medication.
Pausing for the month, and restarting
Pausing and restarting is a decision for the prescribing doctor, and the semaglutide labels have a rule for the restart. After two or more missed weekly doses, the US semaglutide label says to restart the dose escalation at a lower dose to reduce the risk of digestive side effects; the European label says a lower restart dose should be considered if more doses are missed (US label, EU label).
A 2026 case report describes a woman with obesity who stopped semaglutide 2.4 mg for five weeks over Ramadan, restarted at the full dose, and spent four days in hospital with severe vomiting, diarrhoea and electrolyte abnormalities (Valizada 2026). Its authors suggest that people on GLP-1 medicines generally should not stop solely because of daytime fasting unless clinically indicated, and that after a long interruption the medicine be restarted at a lower dose and stepped up gradually. It is one case and the authors' view, not a guideline.
Missed doses and moving the dose day
Both weekly injections can be given at any time of day, with or without meals, and the semaglutide label adds that the time of day can change without changing the dose (tirzepatide, semaglutide). Neither label mentions Ramadan. The rules they do set:
- Tirzepatide, missed dose: give it as soon as possible within 4 days (96 hours); after that, skip it and take the next dose on the usual day. The US and European labels agree (US, EU).
- Tirzepatide, moving the day: allowed as long as at least 3 days (72 hours) separate two doses (US label).
- Semaglutide injection, missed dose: the US label says to give it if the next dose is more than 2 days away and otherwise to skip it; the European label allows it within 5 days (US, EU). Singapore's registered instruction also counts 5 days from the missed dose (NDF), as what to do about a missed dose sets out.
- Oral semaglutide, missed dose: skip it and take the next dose the following day, in both the US and European labels (US, EU).
The timing that suits a fast is for the doctor to set within those limits.
Hari Raya food: HPB's energy figures
HPB has published figures for the Hari Raya dishes below. Its SG FoodID database gives these per default portion, all from laboratory analysis, most of it from 2010 (HPB SG FoodID).
Contains information from Singapore Food Insights Database (SG FoodID) accessed on 7 October 2026 from Health Promotion Board which is made available under the terms found at https://pphtpc.hpb.gov.sg/web/sgfoodid.
| Food | HPB portion | Energy |
|---|---|---|
| Beef rendang | 1 serving-spoon scoop, 100 g | 223 kcal |
| Chicken rendang | 1 scoop, 100 g | 217 kcal |
| Mutton rendang | 1 scoop, 100 g | 182 kcal |
| Ayam opor | 1 scoop, 100 g (90% edible) | 148 kcal |
| Ketupat | 1 whole, 95 g | 87 kcal |
| Lontong rice cakes, sliced | 1 bowl, 154 g | 125 kcal |
| Lontong goreng | 1 scoop, 100 g | 149 kcal |
| Kueh lapis | 1 piece, 72 g | 317 kcal |
| Kueh talam | 1 piece, 131 g | 244 kcal |
| Kueh dodol | 1 piece, 38 g | 125 kcal |
| Kueh salat | 1 piece, 54 g | 82 kcal |
| Kueh bahulu | 1 piece, 9 g | 34 kcal |
| Chicken satay, without sauce | 1 stick, 10 g | 22 kcal |
| Beef satay, without sauce | 1 stick, 12 g | 27 kcal |
Protein varies widely across the table. HPB records 25.5 g of protein in a 100 g scoop of beef rendang, 20.7 g for mutton and 17.1 g for chicken, against 2.2 g in a whole ketupat (HPB SG FoodID). How much protein to aim for is covered in how much protein you need on a GLP-1 medication, and eating out on a small appetite in the hawker centre when you can finish only half a plate.
HPB's Hari Raya guidance on HealthHub puts one pineapple tart at 92 calories and one twisted cookie at 67, and says five cornflake cookies contain almost 200 calories, "almost as much as a small meal" (HealthHub). Its suggestions are to keep portions of festive snacks small, since most are high in butter, fat and sugar, and to serve rendang and lontong with brown rice in place of white (HealthHub).
What to settle with your doctor before Ramadan
The open questions are about timing, and they are clinical ones:
- A planned dose increase. IDF-DAR's 2 to 4 weeks is written for older GLP-1 medicines such as liraglutide, lixisenatide and exenatide, in people with diabetes; the 2023 review suggests at least four weeks, and the labels step the dose up every 4 weeks (IDF-DAR, Alayed 2023, tirzepatide, semaglutide). Whether a step should fall before Ramadan is the prescriber's call.
- When to inject, or when to take a tablet, within the label rules above.
- What to do on a day of vomiting or diarrhoea, for the medicine and for the fast.
- Whether to pause, and how to restart if you do.
For GetLean patients, these are questions to put to Dr Quek before the month starts. At GetLean, the programme is designed to end, and our philosophy is that the medication is the catalyst and the habits are what you keep. Ramadan and Hari Raya are part of the year those habits have to fit.
Individual circumstances vary. Never stop or change a prescribed medicine on your own; that is a conversation with the doctor who prescribed it. Religious questions about the fast are for MUIS, which publishes its answers on ask.gov.sg.
Common questions
Does a GLP-1 injection break the fast?
MUIS cites the view of some scholars that medication given by injection does not invalidate the fast, because it does not go through an open orifice of the body and is not food or drink that nourishes. The MUIS answer is about injected medication in general and does not name any weight-loss medicine.
Is there a Ramadan guideline for tirzepatide or semaglutide?
The IDF-DAR Diabetes and Ramadan Practical Guidelines 2021 name three older GLP-1 medicines as examples (liraglutide, lixisenatide and exenatide), in people with diabetes, and do not mention semaglutide or tirzepatide. A 2026 letter calls tirzepatide during Ramadan in people with obesity without diabetes a critical knowledge gap.
Can you take an oral GLP-1 tablet at iftar?
No label says so. The US label for oral semaglutide says to take it in the morning on an empty stomach, and the European label says on an empty stomach after a fast of at least 8 hours, then to wait at least 30 minutes before eating or drinking. When to take it during Ramadan is for the prescribing doctor to decide.
What if you vomit while fasting on GLP-1 medication?
MUIS says involuntary vomiting does not invalidate the fast, but that if it happens because of sickness you have to consider breaking the fast and making it up on another day. The labels warn that vomiting and diarrhoea can lead to dehydration, and the US tirzepatide guide says to tell your doctor right away if they do not go away.
Should you pause GLP-1 medication for Ramadan?
That is a decision for the prescribing doctor, made before the month starts. After two or more missed weekly doses in a row, the US semaglutide label says to restart at a lower dose; the European label says a lower restart dose should be considered if more doses are missed. A 2026 case report described a four-day hospital stay after a full-dose restart that followed a five-week Ramadan pause.