These stocks have the most at risk as patients on Ozempic eat less, according to Morgan Stanley

The use of weight-loss drugs such as Ozempic is poised to change consumer consumption patterns, but not every food-related company will get hit in the same way, according to Morgan Stanley. The medical breakthroughs have boosted the shares of pharmaceutical companies Novo Nordisk and Eli Lilly and led Wall Street to speculate on the economic impact on everything from gyms to airlines. Demand for Ozempic is so high that Denmark's Novo Nordisk has had to ration the drug . But restaurants and food retailers seem like the most direct play outside of the drugmakers themselves. Morgan Stanley analyst Pamela Kaufman used data from research firm Numerator to look at which companies are more reliant on the spending from obese customers. The research found that heavier customers had higher “buy rates” for certain categories of food associated with weight gain, which could lead to an uneven cutback in spending if the drugs are broadly adopted. “We estimate a 1-2% theoretical impact on spending from this analysis across snacks, sugary drinks, alcohol, and fast food, assuming 5-10% of the population is on [new weight-loss drugs]. … However, our survey data and medical studies point to a more drastic 60-70% reduction in consumption of less healthy categories, which suggests buy rates could fall even more,” Kaufman said in a note to clients earlier this week. The research showed that stocks tied to cheaper food were more exposed than other food manufactuers to overweight customers. Fast food restaurants were especially vulnerable. “Shoppers with obesity spend more at large fast food brands and, on a relative basis, less at fast casual restaurants and casual diners,” Morgan Stanley said. The fast food chain highest on the list is Canada's Tim Hortons, now part of Restaurant Brands International . Over the past year, that chain has a 20% higher buy rate from obese customers than those without. However, Restaurant Brands' other brands, including Burger King, have less drastic differences. Another chain with high exposure to obese customers is The Habit Burger chain, which was bought by Yum Brands in 2020. Yum's other properties, including Taco Bell, rank lower on the list of restaurant chains that are most exposed to diminished spending. One stock that is closer to a risky pure play is McDonald's , which is second highest on the list, according to the Morgan Stanley research. The concerns about Ozempic and similar drugs may already be affecting fast food stocks. All three of those cited are underperforming the S & P 500 year to date. Yum Brands has the worst performance, with shares roughly flat for the year. Fast food restaurants aren't the only companies in the U.S. that are could be hurt by slimmer customers. Low cost retailers like Walmart and snack and beverage companies like Pepsico are also exposed, according to the Morgan Stanley research. Those stocks have also underperformed the S & P 500 in 2023. — CNBC's Michael Bloom contributed reporting.