Weight loss medication: semaglutide, tirzepatide and metformin explained

How GLP-1 medications work

Semaglutide mimics GLP-1, a gut hormone released after meals that signals fullness, slows how quickly the stomach empties and helps regulate blood sugar. Tirzepatide acts on GLP-1 receptors and also on receptors for a second gut hormone, GIP. In practice, both tend to make smaller portions feel satisfying and can quiet the constant background thoughts about food that many people describe.

Neither medication works in isolation. People generally do best when the medication is paired with enough protein, strength training, decent sleep and a plan for what happens after the dose stops rising. Your clinician builds that plan with you.

Compounded versus branded: what is actually different

Wegovy and Ozempic contain semaglutide; Zepbound and Mounjaro contain tirzepatide. These branded products are FDA-approved and were studied in large clinical trials. Compounded semaglutide and tirzepatide are prepared by licensed pharmacies for individual patients. They are not FDA-approved, the FDA does not review them for safety, effectiveness or quality, and the trial results for branded drugs do not transfer to them.

The FDA has also warned that some products sold online use salt forms, such as semaglutide sodium or semaglutide acetate, which are not the same active ingredient as the approved drugs, and that it has received reports of dosing errors with compounded injections. Ask exactly what your prescription contains, and follow the measuring instructions your pharmacy gives you.

Injections or oral capsules

HealifyMD offers compounded semaglutide and tirzepatide as weekly injections and as daily oral capsules. Peptide drugs are partly broken down in the digestive tract, so absorption by mouth is lower and more variable than by injection. Evidence for oral semaglutide comes from the branded tablet, not compounded capsules, and there is no FDA-approved oral tirzepatide.

The better choice is usually the one you will take consistently. Some people prefer to avoid needles; others prefer a once-weekly routine. Your clinician can explain the trade-offs and help you switch later if your first choice does not suit you.

What results to expect and how fast

Appetite often changes within the first few weeks, while weight change unfolds over months. We do not promise a particular number of pounds, because response varies widely and trial averages belong to the branded products that were studied. Doses are usually raised gradually so your body can adapt.

A plateau does not always mean the medication has stopped working. Low protein intake, alcohol, poor sleep, late-night eating or simply needing less energy at a lower weight can all play a part. Tell your clinician rather than raising your own dose.

Side effects and serious warnings

The most common side effects are gastrointestinal: nausea, vomiting, diarrhea, constipation, heartburn and stomach pain. They tend to be worst at the start and after dose increases, and they often ease with time, though not always.

Both medications carry a boxed warning because they caused thyroid C-cell tumors in rodents; it is not known whether they do so in people, but they should not be used if you or a family member has had medullary thyroid cancer or MEN 2. Other important risks include pancreatitis, gallbladder disease, low blood sugar when combined with insulin or sulfonylureas, and kidney strain from dehydration. These drugs are not for use in pregnancy.

Protecting muscle while you lose weight

When weight comes off quickly, some of it is lean tissue, and that matters more after 45 when muscle is already harder to keep. Eating less overall can quietly cut your protein intake too. Prioritizing protein at each meal and doing muscle-strengthening work at least two days a week are the two most practical defenses. If you are new to lifting or have joint or heart issues, check with your clinician before starting a program.

What happens when you stop

Appetite usually returns within weeks of stopping, and many people regain some or most of the weight without a plan to replace what the medication was doing. Some people taper to a lower maintenance dose, some stop after markers improve, and some continue long term. This is a decision to make with your clinician, ideally before you reach your goal.

Where metformin fits

Metformin is not a weight-loss drug in the same sense. It mainly improves how your body responds to insulin, and weight effects are usually modest. It may be considered when insulin resistance or prediabetes is part of the picture, sometimes alongside a GLP-1. Long-term use can lower vitamin B12, so periodic testing makes sense.