A YouTuber tried a Michael Phelps-inspired 12,000 calorie diet and training routine and was overwhelmed by the carbs and cardio

• YouTuber Will Tennyson challenged himself to a diet and training routine inspired by Michael Phelps.
• He ate around 12,000 calories, with four energy drinks and two cups of coffee.
• He said swimming and strength training left him exhausted and he needed all that food for fuel.

At his peak, swimmer Michael Phelps, 23-time gold medalist, had a superhuman training schedule, and fueled his workouts with 8,000 to 10,000 calories a day, according to NBC Sports.

YouTuber Will Tennyson, known for trying extreme lifestyle and fitness challenges, spent a day following an eating and training routine inspired by a rumor from the 2008 Beijing Olympics that Phelps ate up to 12,000 calories a day, six times what the average person needs.

He said the workouts were exhausting, but made him a better swimmer, while the high carb and caffeine content of the diet left him feeling jittery and full by the end of the day.

The YouTuber ate 12,000 calories a day and trained like the Olympian

Tennyson tackled the eating challenge by splitting it into three large meals based on Phelps' rumored eating habits.

"His training is pretty intense but his diet is even more intense," Tennyson said.

Here's what Tennyson ate:

Breakfast: two cups of coffee, a five-egg omelet, grits, three fried egg sandwiches, French toast, and chocolate chip pancakes.

Lunch: two energy drinks, two large ham and cheese sandwiches, and pasta with tomato sauce.

Dinner: two energy drinks, a large pepperoni pizza, and a pound of pasta and sauce.

Tennyson said he was surprised by the lack of veggies, and the high-carb content was exhausting but helped fuel the workouts.

"With all that cardio from the swimming, you're making use of the food," he said.

Phelps' training includes 50 miles of swimming a week and strength exercises in the gym

After breakfast, Tennyson tried Phelps' favorite training set of four drills, working on speed and swimming techniques such as the butterfly and the breast stroke.

"Swimming is a deceivingly hard workout. My lats are fried," he said afterward.

Two hours after lunch, Tennyson hit the gym to try some Olympic-quality bodyweight training. His goal was Phelps' standard set of 34 pull-ups - Tennyson managed 20.

The rest of the session included TRX bands, core exercises, dumbbell shoulder presses, squat jumps, and sled pulls.

By the end, Tennyson was lying on the floor exhausted, and said he felt like he needed more carbs to replenish his energy.