Treating Obesity Is Treating the Brain | Dr Elizabeth Kazarian

What It Covers

Dr. Elizabeth Kazarian, a dual board-certified family medicine and obesity medicine physician, explains how GLP-1 medications work primarily by targeting brain-based hunger signaling rather than willpower, while navigating insurance barriers, dosing protocols, compounding pharmacy risks, and the systemic failures that prevent patients with obesity from accessing evidence-based treatment in the United States.

Key Questions Answered

• •GLP-1 Brain Mechanism: GLP-1 medications reduce what clinicians call "food noise" — the constant, intrusive cognitive preoccupation with eating that consumes mental bandwidth for people with obesity. This is not a willpower deficit; it is a neurological signal. When that signal is quieted pharmacologically, patients report spontaneously initiating exercise for the first time, because mental capacity previously consumed by hunger becomes available for other behaviors. Treating obesity, therefore, means treating the brain first.
• •Tirzepatide vs. Semaglutide Selection: When formulary access permits, tirzepatide (dual GLP-1/GIP agonist) produces stronger weight loss outcomes at equivalent doses compared to semaglutide (single GLP-1 agonist). Tirzepatide also carries FDA approval for obstructive sleep apnea, providing an additional insurance approval pathway. In practice, semaglutide (Wegovy) dominates formularies because Novo Nordisk secured better pharmacy benefit manager rebates, making insurance coverage the primary driver of prescribing decisions rather than clinical preference.
• •Compounded GLP-1 Safety Risk: Compounded semaglutide and tirzepatide were legally permitted during FDA shortage periods, but that shortage designation has ended. Pharmacies adding ingredients like glutathione or vitamin B12 to tirzepatide exploit a regulatory loophole to continue compounding. Independent testing of compounded GLP-1 samples across the US has revealed inconsistent purity and active ingredient concentrations. Eli Lilly has documented adverse reactions from compounded versions. Compounded retatrutide is entirely illegal, as it has not completed Phase 3 trials.
• •Dosing and Rate of Loss: Tirzepatide dosing begins at 2.5mg and escalates through 5, 7.5, 10, 12.5, and 15mg increments. Kazarian avoids skipping doses and monitors the weight-loss curve to begin reducing medication before reaching target weight, allowing momentum to carry the patient to goal without overshooting. Losing weight too rapidly increases muscle mass loss risk and correlates with faster regain. Slower loss is more sustainable and may have a greater effect on hunger set-point recalibration over time.
• •Anhedonia Monitoring at Higher Doses: A clinically significant but underreported side effect at higher GLP-1 doses is anhedonia — a blunted motivation and reduced pleasure in previously enjoyed activities. Kazarian screens for this at every follow-up visit. When detected, reducing the dose typically resolves the symptom. This side effect is distinct from the appetite suppression mechanism and signals that the mesolimbic reward system is being over-suppressed. Patients self-managing doses without physician oversight through telehealth platforms are at particular risk of missing this.
• •Insurance Navigation and Access Workarounds: Insurance companies use BMI cutoffs — typically 30 or above — as hard eligibility thresholds for GLP-1 coverage, ignoring metabolic markers like HbA1c, ApoB, or race-adjusted BMI thresholds (23/27 for Southeast Asian patients, which appears on obesity medicine board exams). Practical access workarounds include Mark Cuban's Cost Plus Drugs pharmacy, which bypasses pharmacy benefit managers entirely, GoodRx coupons for lowest available pharmacy pricing, and Lilly Direct's direct-to-consumer program, which has offered tirzepatide at approximately $500 per month out of pocket.
• •Protein, Fiber, and Hydration Minimums on GLP-1s: Reduced appetite on GLP-1 medications frequently causes patients to fall below nutritional minimums. Kazarian sets explicit daily targets: approximately 25g fiber for women, 30g for men, with protein and fiber distributed evenly across meals rather than concentrated at day's end. Hydration targets around 1.5 liters of water daily, as patients report reduced thirst drive on the medication. Inadequate hydration compounds GLP-1-related constipation. If a patient cannot meet these minimums, the dose is likely too high and should be reduced.