The first month on a GLP-1, week by week
The starter dose is not supposed to do much. The first month is for your gut to get used to the drug, and for you to build the log your prescriber will read at week four.
Both semaglutide and tirzepatide start at a dose that is deliberately too low to be the treatment. Wegovy starts at 0.25 mg a week, a tenth of the maintenance dose. Zepbound starts at 2.5 mg, a sixth of the maximum. The point of month one is tolerance, not weight. If the scale barely moves, the drug is working as designed.
Week 1: the first shot
Pick a day you can keep. The same weekday every week, at a time you will remember, is the single most useful habit on these drugs. Inject under the skin of the abdomen, thigh or upper arm, and note which. Most people feel nothing on day one. Appetite usually drops within a day or two, nausea, if it comes, shows up on day two or three and eases by the weekend.
Log it. Dose, time, site. That first entry is the anchor for everything after.
Week 2: the shape of the week
By the second shot you will have a sense of the rhythm. Drug levels peak a day or two after the injection and drift down over the week, and side effects follow the same curve. Eat small. Stop before full, because fullness arrives late on these drugs and the plate you would have finished in June is now too much. Protein first, then vegetables, then the rest. Water through the day, especially if nausea has you eating less.
Week 3: constipation, fatigue, and the food you no longer want
The slower stomach that reduces appetite also slows the rest of the gut. Constipation shows up here for a lot of people. Fibre, fluids and walking fix most of it, and a conversation with your prescriber fixes the rest. Fatigue is common in the first fortnight and usually lifts. Some foods stop appealing, fried and fatty ones first. Let them go.
Week 4: the review
At four weeks the label allows the first step up, 0.25 to 0.5 mg on semaglutide, 2.5 to 5 mg on tirzepatide. Whether to take it is a decision for the person who wrote the prescription, and they will make it on how the month went. Bring them the log: which days the nausea ran, whether you vomited, how the bowels behaved, what you ate, and the weight line if you have one. "Fine, mostly" is not an answer they can act on. Day two and three nausea, gone by day four, every week, is.
The schedule you are on
| Period | Dose | Notes |
|---|---|---|
| Weeks 1 to 4 | 0.25 mg once weekly | Starter dose, not meant to work yet |
| Weeks 5 to 8 | 0.5 mg once weekly | |
| Weeks 9 to 12 | 1 mg once weekly | |
| Weeks 13 to 16 | 1.7 mg once weekly | |
| Week 17 on | 2.4 mg once weekly | Maintenance dose |
| Period | Dose | Notes |
|---|---|---|
| Weeks 1 to 4 | 2.5 mg once weekly | Starter dose, not meant to work yet |
| Weeks 5 to 8 | 5 mg once weekly | |
| Each step after | +2.5 mg after at least 4 weeks | 7.5, 10, 12.5 mg |
| Maximum | 15 mg once weekly | Maintenance is 5, 10 or 15 mg |
Ozempic follows the same first two steps as Wegovy and tops out at 2 mg. Your prescriber may hold any step longer than four weeks, and many do.
What to log in month one
- Every dose, with the site. Rotate. The app reminds you.
- Side effects as notes on the dose, with the day after the shot and a severity.
- Food, at least roughly. Protein is the number to watch, because you are eating less of everything and muscle is what you do not want to lose.
- Weight, weekly, same day, same conditions. Daily weighing on a GLP-1 is noise.
Logging on Peptide AI is free, and that includes GLP-1s. The dose log, the titration schedule, vials with doses remaining, injection sites with a rotation reminder, nutrition, supplements and training are all on the free tier with no card. Premium adds bloodwork, Oura, WHOOP, Garmin, Apple Health and Health Connect on the same timeline, the body scanner and Remi, the coach that answers from your own log. The pricing page has the three plans.
Questions people ask
How much weight do you lose in the first month on a GLP-1?
Usually a little, often two to four percent of body weight, and some people lose none. The starter dose is for tolerance. The trial results people quote, around 15 percent on semaglutide and around 21 percent on tirzepatide, are at full dose over more than a year.
What should I eat in the first month on Ozempic or Mounjaro?
Smaller meals, protein first, fibre and fluids for the gut, and less of anything fried or fatty, which sits badly on a slower stomach. Stop eating before you feel full, because fullness arrives late.
When do GLP-1 side effects start?
Nausea, if it comes, usually starts a day or two after the first shot and eases within a few days. Constipation builds over the second and third week. Both tend to settle by week four, which is why the dose steps are four weeks apart.
Sources
- Wegovy prescribing information, Novo Nordisk
- Zepbound prescribing information, Eli Lilly
- Once-weekly semaglutide in adults with overweight or obesity (STEP 1), New England Journal of Medicine, 2021
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1), New England Journal of Medicine, 2022
