GLP-1 Year in Review: Tracking Your Annual Weight Loss Journey

Introduction

A full year on a GLP-1 is enough time to know whether the medication is working, what it is costing you in side effects and money, and where the next 12 months should go. Most patients have never run a proper annual review on a weight loss treatment because most weight loss treatments never lasted a year. With semaglutide and tirzepatide, that has changed.

The big clinical trials run on a 68 to 72 week clock, which is close to a calendar year of dosing once you account for the titration ramp. STEP 1 reported 14.9% average body weight loss for semaglutide at 68 weeks (Wilding et al. 2021 NEJM). SURMOUNT-1 reported 20.9% for tirzepatide at the highest dose by 72 weeks (Jastreboff et al. 2022 NEJM). That is the benchmark to compare yourself against, with the caveat that trial averages hide huge individual variation.

This guide walks through the six checks worth running at the one-year mark, the labs to ask for, and the decisions that usually come up next.

At TrimRx, we believe that understanding your options is the first step toward a more manageable health journey. You can take the free assessment quiz if you’re ready to see whether a personalized program is a fit for you.

Check 1: How Does Your Weight Loss Compare to the Trial Averages?

Start with the basic math. Take your starting weight at the first injection and compute the percent change. If you started at 220 pounds and now weigh 187, that is 15% loss. A 15% loss after a full year of semaglutide puts you right at the STEP 1 trial average. A 15% loss after a full year of tirzepatide puts you below the SURMOUNT-1 mean of 20.9%, which is worth a conversation with your provider.

Quick Answer: STEP 1 trial mean weight loss was 14.9% at 68 weeks on semaglutide 2.4 mg; SURMOUNT-1 was 20.9% at 72 weeks on tirzepatide 15 mg

Trial averages are not goals. They are reference points. The trial data shows wide spread. SURMOUNT-1 had roughly 36% of tirzepatide patients lose more than 25% of body weight and about 9% lose less than 5%. STEP 1 had a similar shape with smaller magnitude. Where you land in that distribution depends on adherence, dose, baseline weight, sleep, alcohol intake, muscle mass, and probably genetics that are not yet measurable.

If you are well below the trial average and you have been on the maximum tolerated dose for at least 6 months, the next conversation is about whether the medication is the right fit or whether the dose needs to go up.

Check 2: How Much of Your Loss Was Fat Versus Muscle?

Total body weight on a scale does not separate fat from lean tissue. The published GLP-1 trials that measured body composition with DEXA found that roughly 75% of the weight lost on semaglutide or tirzepatide was fat mass and 25% was lean mass (Wilding et al. 2021 NEJM substudy, and a SURPASS substudy reported similar ratios).

That ratio is in line with what bariatric surgery produces and what dieting alone produces. It is not unique to GLP-1s. The reason it matters is that lean mass loss is hardest to recover, and lean mass drives resting metabolic rate.

The practical implication for year one is protein and resistance training. The American Society for Nutrition and most weight loss research point to at least 1.2 to 1.6 grams of protein per kilogram of body weight per day during active weight loss, with the upper end of that range for older adults. Resistance training 2 to 3 times per week preserves lean mass during a calorie deficit. If you have done neither, year two is the time to start.

Check 3: What Did Your Labs Do?

The metabolic improvements on GLP-1s often outpace the visible weight changes. Run a fasting lab panel at the one-year mark and compare against your baseline before starting the medication. The most informative markers are HbA1c, fasting glucose, total cholesterol, LDL, HDL, triglycerides, eGFR, ALT, AST, vitamin D, B12, and ferritin.

Expected patterns from the trial data: HbA1c drops in people with type 2 diabetes or prediabetes, often by 1 to 2 percentage points on tirzepatide (SURPASS-2 reported mean HbA1c reductions of 2.0 to 2.3% on tirzepatide). Triglycerides fall. HDL often rises modestly. LDL changes are mixed. ALT and AST often improve in patients with fatty liver, which mirrors the ESSENCE phase 3 data showing semaglutide produced MASH resolution in significantly more patients than placebo.

eGFR is worth tracking because the FLOW trial (Perkovic et al. 2024 NEJM) showed semaglutide produced a 24% reduction in kidney disease progression and cardiovascular death in patients with type 2 diabetes and chronic kidney disease. If your eGFR was borderline at baseline, the year-one number tells you whether the medication is doing its kidney work.

B12 and ferritin can drop on prolonged reduced intake, particularly if protein has been low. If either is at the bottom of the lab range, year two should include diet changes or supplementation.

Check 4: What Did Your Blood Pressure and Cardiovascular Markers Do?

Weight loss of 10% or more typically produces measurable blood pressure improvements. The SELECT trial (Lincoff et al. 2023 NEJM) randomized over 17,000 adults with overweight or obesity and established cardiovascular disease but no diabetes, and showed a 20% reduction in major adverse cardiovascular events on semaglutide 2.4 mg over a mean follow-up of about 3 years. That benefit started showing up in the first year of dosing.

For your personal review, compare resting blood pressure and resting heart rate to where they were before the medication. Many patients see systolic drops of 5 to 10 mmHg and modest heart rate reductions. If you started the year on antihypertensive medications, your dose may need to come down, which is a good problem and a conversation with your prescriber.

If your blood pressure has not improved despite significant weight loss, look at sleep apnea. The SURMOUNT-OSA trial led to tirzepatide’s December 2024 FDA approval for moderate to severe obstructive sleep apnea in adults with obesity. Untreated OSA holds blood pressure up regardless of weight.

Check 5: What Side Effects Are Still Active?

Most GI side effects from semaglutide and tirzepatide are concentrated in the first 8 to 16 weeks of dosing and during dose escalations. By month 12, the typical patient is on a stable dose and has either adapted to the medication or has lingering symptoms worth addressing.

The most common one-year residuals are mild constipation, occasional nausea after large or fatty meals, reduced alcohol tolerance, and lower thirst. Constipation responds to fluid, fiber, and walking. Nausea after large meals responds to smaller, evenly spaced meals. Reduced thirst is worth tracking because dehydration sneaks up on GLP-1 users who don’t notice it.

Less common but worth mentioning to a provider: persistent reflux, gallbladder symptoms, ongoing hair shedding past month 6, and any pancreatitis-like pain. GLP-1s carry a known small increase in gallstone risk during rapid weight loss, and any right upper quadrant pain after fatty meals deserves an ultrasound rather than wait and see.

Key Takeaway: Body composition matters: DEXA studies show GLP-1 weight loss is roughly 75% fat mass and 25% lean mass, comparable to surgical weight loss

Check 6: What Is the Plan for Year Two?

The conversation at the 12-month mark usually falls into one of three buckets.

Bucket one is continue at the current dose. This fits patients who have hit a satisfactory weight, have stable labs, tolerate the medication, and want to stay there. Most clinical guidance now treats obesity as a chronic condition like hypertension, and discontinuation often produces regain. The STEP 1 extension data (Wilding et al. 2022 Diabetes, Obesity and Metabolism) showed roughly two-thirds of lost weight returned within a year of stopping semaglutide.

Bucket two is dose adjustment. If weight loss has stalled below your trial-average benchmark and you are not yet on the maximum dose, a step up is the next move. If you are at the top dose and have hit a comfortable place, some patients find a step down maintains weight at a lower side effect cost and lower price.

Bucket three is medication change. Patients who lost less than 5% on semaglutide after a full titration year may do better on tirzepatide based on head-to-head SURMOUNT-5 data (Aronne et al. 2024 NEJM), which showed tirzepatide produced superior weight loss to semaglutide at 72 weeks.

A free assessment quiz with TrimRx can confirm which bucket fits and whether a personalized treatment plan needs to change.

How Do You Track All This Without a Spreadsheet From Hell?

Pick five numbers and log them monthly. Weight on the same morning conditions, waist circumference at the navel, systolic blood pressure, resting heart rate, and a 1 to 10 rating of how you feel that month. Five numbers in a phone note is enough to spot trends.

For labs, once or twice a year is plenty. Pre-dose baseline, then 6 months and 12 months. After year one, annual labs match what most primary care providers already do.

For photos, monthly front and side photos in the same clothing and lighting catch changes the scale misses. Body composition is often shifting even when weight is flat.

What Does the Trial Timeline Look Like for the Year AHEAD?

GLP-1 weight loss is not linear. Most patients lose the fastest in months 3 to 6 after reaching their target dose, slow through months 6 to 12, and approach a plateau by month 12 to 18. The STEP 1 weight curve in the NEJM paper flattens noticeably after week 60. SURMOUNT-1 showed the same shape with later plateau on the highest dose.

If you are at month 12 and still losing, you are not at the end of the curve. Many tirzepatide patients lose meaningful weight through month 18 to 20. If you are at month 12 and flat for 3 to 4 months, that is a plateau worth a clinical conversation rather than a dose problem to solve at home.

Bottom line: The SELECT trial showed 20% MACE reduction in non-diabetic patients on semaglutide with established cardiovascular disease

FAQ

What Is a Good 12-month Result on Semaglutide?

The STEP 1 trial average was 14.9% body weight loss at 68 weeks on 2.4 mg. Anything in the 10 to 20% range is consistent with the published distribution. Below 5% after a full titration year is a reason to discuss alternatives with a provider.

What Is a Good 12-month Result on Tirzepatide?

SURMOUNT-1 reported 20.9% mean loss at 72 weeks on the 15 mg dose. The range was wide, with about a third of patients losing more than 25%. Anything in the 15 to 25% range is solidly within the trial distribution.

Should I Stop the Medication After a Year If I Hit My Goal?

Most current guidance treats obesity as a chronic condition. The STEP 1 extension data showed that two-thirds of the weight returns within a year of stopping. Many patients now plan for indefinite use, sometimes at a lower maintenance dose.

Will My Insurance Cover the Medication for Year Two?

Coverage policies change frequently. Many commercial plans now require ongoing documented benefit (weight loss of at least 5% sustained) to continue coverage. Compounded options through telehealth platforms can be a backstop when commercial coverage is denied.

What Labs Should I Run at the One-year Mark?

HbA1c, fasting glucose, full lipid panel, eGFR, ALT, AST, vitamin D, B12, and ferritin cover the essentials. Add a thyroid panel if you have a personal history. Compare to baseline labs from before you started dosing.

Why Is My Weight Loss Slower Than the Trial Average?

Adherence, dose, alcohol intake, sleep, baseline weight, body composition, and underlying conditions all influence response. A muscular person at 200 pounds will lose less in absolute pounds than a sedentary person at 280 pounds, even on the same dose. Below 5% after a full titration year is the threshold for a clinical rethink.

Can I Switch From Semaglutide to Tirzepatide at Year One?

Yes, with a provider’s guidance. The SURMOUNT-5 trial (Aronne et al. 2024 NEJM) showed tirzepatide produced superior weight loss compared to semaglutide head-to-head. Switching is appropriate for patients with inadequate response to semaglutide at a maximum tolerated dose.

Disclaimer: This content is for informational purposes only and does not constitute medical advice. It is not intended to diagnose, treat, cure, or prevent any disease or condition. Individual results may vary. Always consult a qualified healthcare professional before starting any weight loss program or medication.