Quoc N. Dang, DO, FASMBS | Bariatric & Metabolic Surgery | April 2026
A lot of patients come in having already decided they want a GLP-1 medication. They have read about the results. They know the trial numbers. Some of them can tell me the specific dose that produced the best outcomes in SURMOUNT-1. That level of preparation is genuinely useful, and I would rather have an informed patient than one who is starting from scratch.
But knowing what a medication does is different from knowing whether it is right for you. That second question is the one I am actually trying to answer in the first appointment. And the evaluation behind it is more involved than most patients expect.
The Metabolic Picture Comes First
Before anything else, I want to understand what is actually driving the weight. That sounds obvious, but it matters more than most patients realize when it comes to predicting how well a medication will work.
Insulin resistance is the most common factor. A patient who has been carrying significant weight for years, particularly around the abdomen, is almost always dealing with some degree of insulin resistance even if their fasting glucose looks normal. Fasting insulin, HbA1c, and a full metabolic panel tell me more than weight alone. I have seen patients with a BMI of 33 and severe insulin resistance who respond exceptionally well to tirzepatide, and patients with a higher BMI and cleaner metabolic labs who do not respond as strongly. The number on the scale is context, not the whole story.
Thyroid function is another area I check routinely. Undiagnosed or undertreated hypothyroidism makes weight loss significantly harder and can blunt the response to medication. It is also common enough that finding it is not rare. A TSH alone is not enough in most cases; free T4 tells me more. If a patient has been struggling with weight despite reasonable effort and their thyroid has never been properly evaluated, that is something worth addressing before or alongside starting a medication.
I also ask about sleep. Obstructive sleep apnea is present in a substantial portion of patients seeking weight loss treatment and is frequently undiagnosed. Untreated apnea affects cortisol, insulin sensitivity, and energy regulation in ways that actively work against weight loss. A patient who is not sleeping is fighting the medication. Getting that addressed first or concurrently makes a real difference in outcomes.
Weight History Matters More Than Current Weight
I spend more time on weight history than most patients expect. When did the weight start? What were the circumstances? What has been tried before, and what happened? These are not background questions. They are clinically relevant.
A patient who has been at a stable elevated weight for fifteen years is in a different metabolic situation than one who gained forty pounds over the past two years following a medication change or a major stressor. The body adapts to a set point over time. The longer a weight has been maintained, the more the body will work to defend it. That affects how much effort the treatment requires and what realistic expectations look like.
Previous medication trials also matter. If a patient tried semaglutide and stopped because of side effects at a low dose, that is different from stopping because insurance ran out. If they responded well to phentermine years ago and then regained, that tells me something about their appetite regulation. If they lost significant weight during a structured program and maintained it for two years before regaining, that tells me something else. The history is data.
What the Evaluation Actually Involves
A proper evaluation for any weight loss medication is not a brief online questionnaire. At minimum it should include a review of current medications, a full medical history, relevant lab work, and a direct conversation about what has and has not worked before. The physician is trying to build a complete metabolic picture, not just confirm that the BMI qualifies.
Current medications are particularly important. A number of common drugs contribute meaningfully to weight gain or make weight loss harder: certain antidepressants, antipsychotics, beta blockers, corticosteroids, insulin secretagogues, and some anticonvulsants. If a patient is on something in one of these categories and it is clinically appropriate to reconsider it, that conversation is worth having before adding another medication. Not always possible, but worth exploring.
Contraindications are also something I take seriously in ways that a fast telehealth intake may not. GLP-1 receptor agonists are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2. Patients with a history of pancreatitis require a careful discussion. Active gallbladder disease matters. Prior hypersensitivity to any ingredient in the formulation. These are not theoretical concerns, and they require an actual clinical conversation, not a checkbox.
Choosing Between Medications
The two medications I prescribe most frequently for weight management are semaglutide and tirzepatide. Both are GLP-1 receptor agonists; tirzepatide adds GIP receptor activity on top. The trial data consistently shows tirzepatide producing more weight loss across every studied dose, with average results from SURMOUNT-1 reaching around 20.9% at 72 weeks compared to roughly 14.9% for semaglutide in the STEP trials.
For most patients with obesity and no significant contraindications, tirzepatide is my default choice based on that data. The exception is cost and coverage. If a patient’s insurance covers semaglutide but not tirzepatide, the covered medication that the patient can actually stay on is better than the superior medication they stop taking after two months because they cannot afford it. Coverage drives a lot of prescribing decisions in ways the trial literature does not capture.
There are also older approved options worth knowing about. Phentermine is still appropriate for short to medium term use in certain patients, particularly those who need a bridge while waiting for insurance approval on a GLP-1 agent. Phentermine-topiramate is more effective than phentermine alone and has a reasonable evidence base. Naltrexone-bupropion has a different mechanism and works well for some patients who have a significant behavioral or reward component to their eating patterns. These are not the medications generating the most attention right now, but dismissing them entirely is a mistake.
Setting Expectations Before the First Dose
I spend time on this in every new consult because the gap between what patients expect and what actually happens early in treatment is where a lot of people stop.
The first four to eight weeks are an adjustment period. Nausea is common, particularly after each dose increase. Most patients experience it to some degree. It is not a sign that the medication is wrong for them; it is what happens while the body adjusts to a new level of receptor activation. It improves. Eating smaller portions, avoiding rich or fatty meals during that window, and staying hydrated gets most patients through it.
Weight loss in the first month is also often slower than patients expect based on what they have read. The drug is working on appetite and metabolism; the scale takes longer to reflect it than the internal changes would suggest. Patients who expect dramatic early results and do not see them sometimes stop before the medication has had time to work properly.
I also make clear early that this is not a short course of treatment. The data on GLP-1 medications and weight regain after discontinuation is consistent: stopping the medication leads to weight regain in most patients, often within months. This is chronic disease management, the same way a patient with hypertension stays on antihypertensives. Framing it that way from the start leads to better decisions when obstacles come up later.
What Actually Predicts a Good Outcome
In my experience, the patients who do best are not necessarily the ones who were most motivated at the start. Motivation at baseline is easy to have. It is a cheap signal.
The patients who get the best results are the ones who show up to follow-up, who communicate early when they are having side effects instead of stopping on their own, who make the dietary and activity adjustments that complement what the medication is doing, and who understand from the beginning that the medication is a tool, not an endpoint. Those behaviors predict outcomes more reliably than BMI at baseline or how much weight someone says they want to lose.
The other factor that matters considerably is consistent access. Insurance disruptions, supply shortages, and cost changes have derailed more treatment courses than side effects have. Identifying potential access issues before starting and having a plan for them, whether that involves manufacturer savings programs, prior authorization appeals, or a backup option, is part of getting a good outcome. It is not a detail to figure out later.
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About the Author
Quoc N. Dang, DO, FASMBS, is a fellowship-trained bariatric and metabolic surgeon with a focus on obesity medicine and pharmacological weight management. He writes about evidence-based approaches to weight loss at WeightLossPills.com.