A 57-year-old Tennessean went viral on TikTok in late February after announcing his commitment to an unconventional approach to weight loss: eating only McDonald’s for 100 days.

“I know some of you are thinking that might be crazy, but I’m gonna eat nothing but McDonald’s for the next 100 days,” Kevin Maginnis shares in his first-ever TikTok.

As day 44 rolls in, Maginnis, who introduces himself to his over 76,000 TikTok followers as bigmaccoaching, has stayed true to his plan. In fact, it has worked, he shares with his newfound following. He has lost 34 pounds thus far and reports having improved cholesterol levels.

His approach seems counterintuitive, but Maginnis explains the secret sauce to his success with his easy-to-follow daily guidelines. He eats three McDonald’s meals daily from anywhere on the menu and does not snack in between. He cuts each meal in half and saves the remaining portion for his next meal. He also chooses a bottle of water instead of soda with each meal. For breakfast, he will sometimes choose the Egg McMuffin and hash brown, cut both in half, and save the rest for either lunch or breakfast the next day.

The famed McDonald’s devotee is not bored—at least yet. He celebrated his birthday this week with half of a 10-piece chicken nuggets, apple slices, a couple of dipping sauces, and a “birthday shake”—because McDonald’s, unfortunately, doesn’t offer drive-through birthday cakes.

But Maginnis has faced criticism, with some comments pointing to the renowned film Super Size Me, which documents the negative health outcomes of eating only McDonald’s for 30 days and sheds light on the harmful effects of America’s fast food industry.

Maginnis claps back on the platform, saying for him, it’s “half-size me.” In his mind, portion control overrides food’s nutritional value. He responded to one inquirer who asked why he can’t portion-control home-cooked meals—which are minimally processed, have a lower sodium content, and provide more nutrient variety.

“Overeating at home is what got me in trouble; by creating a ‘leave the food at the house alone’ scenario, it has helped me.”

Experts weigh in on the McDonald’s-only approach

Medical experts are quick to critique Maginnis’s approach.

“I have cardiologists that love it and I have cardiologists that hate it,” he said on day 10 of his challenge on the Today show.

And while Maginnis doesn’t consider his plan a typical diet, calorie-based weight-loss approaches often fail, experts point out.

“Is a calorie a calorie when it comes to weight loss? Technically, yes. That’s what is going to work in this situation,” says Tara Schmidt, lead registered dietitian for the New Mayo Clinic Diet. “The topics that have not yet been addressed, though, are nutrient density (diet quality), balance, and sustainability. Research tells us that any calorie-controlled diet program will work, but most people will experience weight regain when they are no longer able to maintain it.”

While portion control can lead to weight loss, weight should not be framed as the sole measurement of health. Solely focusing on weight glosses over the importance of other health metrics integral to maintaining optimal health and a sense of well-being.

“In the realm of food choices, it’s also notable to consider the quality of food being consumed and its impact on the body,” says Tara Schmidt, lead registered dietitian for the New Mayo Clinic Diet.

In fact, the type of foods we eat can help reduce the risk of chronic conditions like heart disease and diabetes. Highly processed foods, like fried foods, can cause inflammation, putting people at risk for long-term health conditions like heart disease, type 2 diabetes, and cancer. Fast food is also high in sodium and low in fiber, which means it is digested quickly and can induce what feels like a sugar crash, which can negatively affect mood and trigger fatigue.

Eating diverse foods is also associated with a stronger gut microbiome, which helps protect us from illness.

“By consuming a large number of different plant fibers, that gives the building blocks for the emergence of diverse bacterial populations,” Dr. Richard Day, vice president of medical affairs and clinical development at ADM, a food processing company, previously told Fortune.

And the Mediterranean diet—a way of eating based on abundance and the prioritization of a variety of fruits, vegetables, whole grains, and plant-based protein—has been associated with longevity. Aiming for 30 different plants a week can improve the gut microbiome, reducing inflammation and improving heart and brain health. While Maginnis can choose from the entire McDonald’s menu, the options are still limited, as his videos show.

So the McDonald’s-or-bust way may not be for everyone.

And while Maginnis says he understands other factors can improve his overall health, until day 100, he’s sticking with half of the best of what McDonald’s has to offer.