Fittest Man on Earth Justin Medeiros said bulking up with more calories helped him gain strength when he started CrossFit

• The CrossFit star Justin Medeiros said his training prompted him to eat more to boost his strength.
• He eats about 5,000 calories a day and said gaining weight in the offseason made him stronger.

The CrossFit star Justin Medeiros said he ate up to 5,000 calories a day to fuel hours of intense workouts in training.

The 2021 Fittest Man on Earth, which is the title given to the winner of The CrossFit Games, loads up on carbs and often gains weight in the offseason to get stronger, he told Insider in an interview coordinated through his partnership with the sleep-fitness company Eight Sleep.

A competitive wrestler when he was in high school, Medeiros said he started competing in CrossFit as a teenager in 2016. Now 23, he earned third place at his first CrossFit Games in 2020 before taking the top podium spot last year.

He said CrossFit training changed his approach to nutrition, helping him focus on eating for overall gains and performance.

"My goal is to eat as much as I can every day," he said. "I'm eating to fuel myself, not to look the best or be the lightest weight."

He said gaining weight helped him build strength

Medeiros said he saw a major change in his strength when he switched from wrestling to CrossFit and gained about 15 pounds in the process.

"In wrestling, I was trying to eat to perform but stay light. I definitely got stronger when I started eating more," he said.

Now in the offseason, he doesn't worry about gaining extra weight, since it ultimately leads to more strength and performance improvements for competition.

"I'm a little bit heavier right now than I would be in the beginning of the season, but it helps to put on muscle mass, and you have all that food and energy to keep training," Medeiros said.

Bulking, or intentionally eating more to gain weight to maximize muscle growth, is a common technique used by strength athletes and bodybuilders, since the extra calories help speed muscle recovery and strength gains.

Medeiros eats 500 to 600 grams of carbs a day

The biggest change in his diet when he moved from wrestling to CrossFit was eating more carbs, Medeiros said.

"Before, I wasn't eating foods that were higher in carbs. For CrossFit, I need foods that are the most dense in carbs to fuel my long training days," he said.

High-carb foods like oatmeal and fruit are a regular part of his routine.

Other top CrossFit athletes swear by eating plenty of carbs for peak performance, too.

Carbs are an important resource for fueling the body and preventing muscle breakdown during the intense strength and endurance demands of CrossFit, Mike Molloy, a nutrition coach, previously told Insider's Rachel Hosie.

He also gets 250 grams of protein day, supplementing with shakes

Medeiros is also careful to get enough protein, an essential nutrient for athletes to build and maintain muscle.

To hit his goal of 250 grams a day, he said he included protein powder in shakes and smoothies. Medeiros said his fitness hack was making smoothies from whichever fruits and veggies he had around, adding peanut butter for extra calories and flavor.

"A little splash of peanut butter is the pro tip that makes it taste a whole lot better," he said.