Do I need bloodwork while on GLP 1, what your doctor watches and why
By Jimmy, founder of 120to90. Medically cautious, not medical advice. See the disclaimer below. Last updated July 2026.
Short answer, yes, and it is a good thing. A GLP 1 is a powerful prescription medication, and the bloodwork around it is not red tape. It is how your doctor makes sure the medication is helping and not quietly causing a problem. I am not a doctor, so this page does not tell you which tests you need. What it does is explain, in plain language, the monitoring most people can expect, so you walk into your appointments informed and confident.
I am Jimmy. I am 48, on my own road from 120kg toward 90, losing weight under my own doctor on a GLP 1. My blood gets checked, and I am glad it does.
Why bloodwork matters on a GLP 1
Two reasons. First, safety. These medications can affect things like your kidneys, especially if the nausea leaves you dehydrated, and your doctor wants to catch anything early. Second, progress. The scale only tells you that weight is moving, not whether your health markers are improving underneath. Bloodwork shows the real story, your blood sugar, your cholesterol, your organ function. That is the part that actually matters for a longer, stronger life.
What your doctor commonly checks
Every doctor and every patient is different, so treat this as a general map, not a prescription. The tests often discussed around GLP 1 treatment include the following.
- Blood sugar and HbA1c. Since these drugs began as diabetes treatments, your blood sugar control is a core marker, even if you are taking it for weight.
- Kidney function. Dehydration from early nausea and vomiting can stress the kidneys, so this is watched, especially at the start.
- Liver enzymes. A general check that your liver is healthy and handling everything well.
- A lipid panel. Your cholesterol and triglycerides, which often improve as you lose fat.
- Thyroid and other baselines. Your doctor may take a baseline picture before you start and check in as you go.
Your own doctor decides which of these apply to you and when. Bring the list of questions, and ask.
How often you might be tested
Again, this is your doctor’s call. A common pattern is a baseline set of tests before you start, a check in the first few months as your dose settles, and then periodic reviews after that. The early phase tends to get the closest attention, because that is when side effects like nausea are most likely and when dehydration is the main thing to guard against. If you ever feel severe pain, keep vomiting, or feel truly unwell, that is not a wait for the next blood test moment, that is a call your doctor now moment.
The marker most weight plans ignore, your muscle
Here is where most of the conversation goes quiet, and where a man over 45 should pay attention. Standard bloodwork tells your doctor a lot, but it does not usually measure the one thing that decides whether you end up lean and strong or skinny and weak, your muscle. A big share of rapid weight loss can be lean tissue rather than fat, and the scale and a routine blood panel will not flag that for you.
That is the gap 120to90 is built to fill. Alongside your medical monitoring, you track the things that protect muscle, your strength numbers, your waist and your weight against your goal. When your bloodwork is improving and your strength is holding, that is the real win. If you want the method, read our guide to keeping muscle on GLP 1.
How to make your monitoring easier
A few simple habits make the whole process smoother and your results better.
- Stay hydrated, especially early, to support your kidneys through the nausea phase.
- Eat enough protein, roughly 1.2 to 1.6 grams per kilogram of body weight per day, to protect muscle while you lose fat.
- Keep your own records, your weight, your waist and your strength, so you and your doctor see the full picture, not just the labs.
- Ask questions at every appointment, about your results, your dose and anything that feels off.
The medication and the bloodwork are your doctor’s department. The training, the eating and the tracking that keep your muscle are yours, and that is exactly what the free plan is built to handle. When you are ready, the full system lives inside the 120to90 app.
Frequently asked questions
Do you need blood tests to be on a GLP 1?
In most cases your prescriber will want bloodwork before starting and at intervals during treatment, to check safety and track progress. Your own doctor sets the exact schedule for you.
What blood tests are done on a GLP 1?
Commonly discussed tests include blood sugar and HbA1c, kidney function, liver enzymes and a lipid panel, with baseline checks before you start. Your doctor decides which apply to you.
How often do you need bloodwork on a GLP 1?
A typical pattern is a baseline, closer checks in the first few months, then periodic reviews, but the schedule is set by your doctor based on your health.
Does bloodwork show if I am losing muscle?
Routine bloodwork usually does not measure muscle. That is why tracking your strength, waist and weight alongside your labs matters, so you can see whether the loss is fat or muscle.
Disclaimer. I share what I have learned on my own journey and I am not a doctor. GLP 1 medications are prescription drugs and all decisions about testing, dosing and monitoring must be made by your own qualified doctor. Nothing here is medical advice. If anything feels wrong, contact your doctor.