McDonald’s (MCD) has handled low-carb fads, kale revolutions, and the brief reign of cauliflower rice, but its newest rival comes with a prescription label and a co-pay. GLP-1 weight-loss medicines—from injectables like Eli Lilly’s (LLY) Mounjaro and Zepbound to the next wave of oral pills—are reshaping how consumers think about appetite, indulgence, and value, one portion-controlled bite at a time. For McDonald’s, that means the customer now has a second CFO sitting on their shoulder: their endocrinologist.
“Behavior Changes” – McDonald’s and Lilly Read the Same Tea Leaves
On a recent call, McDonald’s CEO Chris Kempczinski acknowledged that as GLP-1 use rises, consumers eat fewer calories and narrow what they order. Eli Lilly’s own leadership has been saying the quiet part out loud for years, with CEO David Ricks noting that people on GLP-1 drugs can cut daily intake by roughly 800 calories and that he expects as many as one-fifth of Americans could eventually use these medicines. In effect, McDonald’s and Lilly are watching the same behavioral curve from opposite sides of the income statement—one sees smaller baskets, the other sees soaring prescription volume.
Eli Lilly’s GLP-1 Engine: Mounjaro, Zepbound, and the Pill on Deck
For Lilly, the GLP-1 revolution is not a side business; it is the business. Mounjaro and Zepbound generated tens of billions of dollars in revenue through 2025, propelling Lilly to best-in-class growth and positioning tirzepatide as one of the world’s top-selling therapies. The next leg comes from an oral GLP-1 (orforglipron) and expanded obesity indications, which could push access well beyond the early-adopter cohort and normalize pharmaceutical appetite control the way statins normalized cholesterol management.
When One Side’s Revenue Growth Is the Other Side’s Check Size
The better Lilly’s GLP-1 franchise performs, the more pressure flows into restaurant P&Ls. Studies and early transaction data suggest GLP-1 users eat 20–30% less food, spend less on fast food, and increasingly favor high-quality proteins over sugary drinks, breads, and alcohol. While Eli Lilly guides to another year of double-digit revenue growth on the back of obesity drugs, analysts are simultaneously modeling slower traffic growth and smaller average tickets for chains most exposed to discretionary calories.
Protein, Portions, and the GLP-1 Playbook Under the Arches
McDonald’s isn’t waiting for a surprise from the drive-thru speaker; it is tailoring the menu to match this new pharmacologically portion-controlled customer. The company is leaning into protein-centric items—beef and especially chicken—and testing high-protein formats and portionable products that let GLP-1 users get their main dish without feeling nudged toward extra fries or a large soda. With emerging research showing that GLP-1 users prioritize main entrées over sides and snacks, the chain is effectively re-architecting its check from “Would you like fries with that?” to “Let’s perfect the entrée you actually came for.”
GLP-1 Users Aren’t Ditching Restaurants—They’re Editing the Order
So far, restaurant traffic has proved more resilient than some of the scarier slide decks implied. Circana and other trackers find that GLP-1 users are still going out but simplifying orders: more mains, fewer sides, and sharper interest in lighter or higher-protein choices, a pattern echoed by broader research showing shifts toward fresher foods and away from heavy, sugar-laden items. That aligns neatly with Lilly’s description of GLP-1 drugs as tools that help people “control our urges,” effectively turning impulse items into line items up for renegotiation.
Value Meals, Smaller Appetites, and Bigger Pharma
Even as GLP-1s tamp down portions, McDonald’s is still leaning hard on value, using bundled meals and sharp price points to stay relevant to households navigating both inflation and new eating norms. The irony is that while McDonald’s trims combo complexity to preserve its average check, Lilly is building a multi-decade franchise out of the very behavior change that makes that trimming necessary. For investors, that sets up an unusual pairing: a fast-food bellwether optimizing for smaller but more efficient orders, and a pharma leader monetizing the macro trend that makes “supersize me” sound like a period-piece reference.
The Long-Term Question: Diet Casualty or GLP-1-Compatible Comfort Food?
The rise of GLP-1 medications is on track to become one of the most significant consumer-health shifts of the decade, with Lilly at the center and companies like McDonald’s recalibrating in real time. The downside risk is straightforward: less volume, fewer add-ons, and an eventual step-down in per-visit spending if GLP-1 uptake reaches the one-in-five Americans that Lilly’s CEO has floated. The upside, at least for McDonald’s, is that by meeting this new customer where they are—smaller portions, more protein, transparent value—it may prove that there is still room in a GLP-1 world for a burger, so long as the science and the seasoning can peacefully coexist.
The Sources
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https://www.circana.com/post/glp-1-users-aren-t-ditching-restaurants-but-their-ordering-habits-are-changing-new-circana-researc[9] - GLP-1 Users Order More Main Dishes, Less Sides – NACS
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