Just Started a GLP-1? Read This First

Starting a GLP-1 is a quiet event. There is no loading dose, no dramatic first day. You inject once, you eat dinner, you sleep. Most people wake up the next morning and feel nothing different. By day three or four something is unmistakably off about hunger — meals get smaller, snacks lose interest, the constant background thought of food softens. That is the drug working.

This guide is the orientation that almost nobody gets at the pharmacy counter. It assumes you already have a prescription — Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda, or a compounded equivalent — and that you are about to take your first injection. The brand names differ but the early playbook is the same.

The first 48 hours

The first injection is anticlimactic by design. Every GLP-1 starts at a sub-therapeutic dose: 0.25 mg semaglutide, 2.5 mg tirzepatide, 0.6 mg liraglutide. These doses exist to introduce your gut to the molecule slowly, not to suppress appetite immediately. Expecting dramatic effect in the first two days is the fastest route to feeling like the medication is not working.

Do the injection itself in the early evening if your schedule allows. Many people sleep through the window when symptoms are most likely to appear — roughly 12 to 36 hours post-dose. The site does not matter much: abdomen, thigh, or upper arm all work. Rotate between weeks. Pinch a fold of skin, push the needle in at 90 degrees, hold for a slow count, withdraw. The pen has a click or audible cue when the dose finishes.

Side effects in the first 48 hours, if they show up at all, tend to be mild: a slight nausea after a heavy meal, a bit more fullness than expected, occasional reflux at bedtime. Severe nausea or vomiting on day one is uncommon on a starter dose. If it happens, contact your prescriber before the next dose — pacing the next step matters.

Hydrate intentionally. Semaglutide and tirzepatide both blunt thirst cues for some people. Sip water on a schedule rather than waiting until you feel thirsty. A slow-emptying stomach handles small frequent sips better than large glasses.

The first week

Week one is mostly observation. Your job is to notice patterns without making large changes. Note when nausea appears, what foods seem to trigger it, how full you feel after a normal-sized portion. Most people are surprised by how quickly portions need to shrink. Half of what you used to eat often feels like plenty.

Eat protein first at every meal. Eggs, yogurt, chicken, tofu, cottage cheese, fish — whatever protein source you actually like. As appetite quiets, the calories you do eat need to be working harder. Protein protects muscle during weight loss, which matters more than any other macronutrient choice on a GLP-1. A rough target is 0.7 to 1.0 grams per pound of goal body weight, but exact numbers matter less than the habit. Use our protein calculator if you want a starting figure.

Pick your weekly injection day and stick to it. Whatever day you took your first dose becomes your weekly day until you stop the medication. Calendar it. Set a phone reminder. Sunday evening is a popular slot because the lowest-symptom window often falls during the weekday workday rather than across Saturday plans.

If you feel basically fine all week — many people do — that is not a sign the medication is not working. Starter doses are deliberately gentle. The visible effects (deeper appetite suppression, weight movement) typically arrive after the first or second dose increase, around week five to week eight.

The first month

The starter dose runs for four weeks. Around week four to five your prescriber will usually step the dose up — 0.25 mg to 0.5 mg for semaglutide, 2.5 mg to 5 mg for tirzepatide, with similar small jumps on the others. This is when most people first feel the drug clearly. Appetite suppression deepens. Side effects can return briefly as the gut readjusts.

Use the first month to set up the routines that will carry the next six months. A consistent injection day. A protein-forward meal pattern. Hydration on a schedule. A weigh-in cadence that does not turn the scale into a daily anxiety — once a week, same day, same conditions is plenty. A few of these habits matter more than any single supplement, meal plan, or workout.

Track non-scale changes alongside weight. Rings fitting differently, fewer joint aches, better sleep, lower resting heart rate, quieter food noise. These often move before the scale does, and they stay relevant when the scale plateaus later. The unofficial term is NSVs — non-scale victories — and they exist for a reason.

By the end of month one most people land somewhere in the range of one to six pounds lost. Some lose nothing measurable on the starter dose; some drop closer to ten. Both are normal. The first month is mostly groundwork. The dose climbing in the second and third month is where the bigger changes typically arrive.

Common questions

Keep exploring

The full week-by-week timelines live at Week 1 Semaglutide and Week 1 Tirzepatide. For the underlying vocabulary, see the GLP-1 glossary.