TikToker eating nothing but McDonald's for 100 days says he is losing weight. "Fries at Fit Guy."

Last month, Kevin Maginnis took to his TikTok channel @bigmaccoaching to try a bizarre weight loss experiment.

"I'm only going to eat McDonald's for the next 100 days," the 56-year-old Nashville native said, "but instead of eating whatever they give me, I'm going to go ahead and cut the split meals just to prove to myself and maybe some of the other people watching that it's not so much what you eat, it's how much we eat that really gets us going."

Challenge @bigmaccoaching: eat mcdonalds with every meal for the next 100 days to lose weight! #mcdonalds #mcdonaldschallenge #weightloss #bigmaccoaching #transformativecoaching #nashvilleweightlosstransformation #weightlossjourney #100daychallenge ♬ Inspirational Emotional Piano - Metrow Ar

This video now has 573,000 views.

Maginnis started her unconventional weight loss plan weighing 238 pounds. He chronicled his diet on TikTok every day, eating three meals a day, but only half the meal.

If you think all Maginnis only eat salads and yogurt parfaits, you're wrong. He eats from the full menu, including Egg McMuffins, Fries and Big Macs. The only rules are to eat half, to drink only water (so soda or juice) and not to snack in between.

Some TikTok users have expressed concern about food waste, but Maginnis assured them that he saves every uneaten meal and eats it the next day.

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Maginnis claims to have lost 12.5 pounds in 10 days. Yesterday he went on the Today Show to discuss his journey, saying he estimates he lost 50 pounds in 100 days.

"My health will be better. My blood tests will be better," he said. "And if you don't believe me, follow me. Let's find out."

Maginnis is not the first to try this experiment. In 2014, a high school biology teacher, John Cisna, ate only McDonald's for 90 days, having his students design his menu. After 3 months, he had lost 37 pounds.

But most nutritionists and doctors don't recommend McDonald's for three meals a day. Sure, you can lose weight, but other health issues need to be considered, including the adverse effects of diets high in sugar, sodium, and fat.

"One of the most immediate effects of eating at McDonald's is feeling extremely tired and groggy after your meal," Bansari Acharya RDN, a registered dietitian nutritionist, told Eat This, Not That. "Your body feels like it has little energy as it tries to digest the excess fat and sugar."

Fast food has also been shown to raise cholesterol levels, destroy healthy gut bacteria, and make you more susceptible to diabetes.