Thai and foreign fighters started to arrive at the open-air gym for their afternoon training. In bright satin shorts, they began jumping rope and jogging around the neighborhood to warm up.

When my motorbike taxi driver dropped me off at Eminent Air Boxing Gym, I started sweating immediately. I wasn't nervous to interview champion muay Thai fighters; I was being cooked alive by the oppressive Bangkok heat. At 90-something degrees with 80 percent humidity, it was impossible to stop the torrential perspiration.

I was there to find out what muay Thai fighters eat during training. What were these hard-bodied men feeding those sculpted abs? After reading about Dwayne "The Rock" Johnson's cod-filled dietary regimen , I was expecting to find a lot of clean eating going on in the muay Thai community. Were muay Thai fighters nutrition purists?

Scorching summer temperatures be damned, these men were embarking on a three-hour training session—their second of the day. I could barely keep the sweat out of my eyes from just standing there. One concerned trainer actually bought me an iced tea to help me cool down.

Lolo Kiatphontip came over from France four months ago, but has visited Thailand for muay Thai training and events seven times before. He'll stay in the Kingdom for about eight months this time. At six in the morning, Lolo gets up to go running on an empty stomach. He is not alone in pushing the morning meal later. Skipping traditional breakfast seems to be normal in the world of muay Thai.

Unlike the fitness freaks I knew back in the United States, these men hardly spoke of supplements—and no one mentioned cod. Instead, I was told that a fighter's diet looks a lot like what most Thais eat.

When they get to breakfast after their grueling morning training, muay Thai fighters go for a breakfast that looks a lot like lunch and dinner. Meals include Thai street food for classics like khao man gai, gra pao, or khao soi.

"In the morning, we don't eat because training starts at seven. We don't really have time—we prefer sleep," another expat, Claudio Amoruso from Italy, tells me. "We wake up and straight away go [to] training. I know it's wrong, because you're supposed to eat before, but if you want to eat you'd have to wake up at least an hour before, and when you train every day, you are tired."

"In Isan, a typical breakfast would include, rice (of course), fish soup, som tam salad (Isan style), eggs, and maybe some boiled vegetables," she said of the diets in the northeast. "In Isan, the people are very poor, so they will catch the fish themselves, or if the gym has a bit of money, will buy from the locals. Pork is more of a treat."

The muay Thai fighter's diet tends to change a bit according to their region. I spoke with Frances Watthanaya, who recently opened a gym in Isan with her husband—a muay Thai fighter himself—about the breakfast of champions.

"Typically, the eggs are a Thai omelet, but with nothing in them," Frances tells me. "This way, the fighters can share better."

Because they're a cheap, complete protein, eggs are also a go-to staple throughout the day for those in training all over Thailand.

When UK expat fighter and Eminent Air Gym legend Melissa Ray was in training, her go-to was a mash-up of porridge, müesli, yogurt, and soy milk. South African fighter Wasim Mather reaches for a tropical fruit smoothie he makes in his apartment before heading outside for chicken and rice.

Just as Thais eat according to region, expat fighters may hold on to their own breakfast preferences even if their diet revolves heavily around Thai street food.

"Rice is always eaten," Frances says. "In Isan, it depends on the location of the gym whether it is sticky rice or regular rice. During weight-cutting, the fighters will eat rice soup."

There's a lot of rice-eating by foreigners and locals alike. It seems that rice is to muay Thai champs as cod is to The Rock.

"Eating rice is the best for training, because it gives you powerful training and it does not make you feel heavy," he tells me. "If you eat pasta, you need to do [it] two or three hours before training. There's no way you can eat an hour before training."

The fighters favor the simple carbohydrate because it's easy to digest. The Italian Claudio prefers it to his country's beloved pasta for that reason.

"This schedule doesn't allow for much other than training, as the pad work, clinching, and running is very demanding, and usually most athletes will sleep during the day," Phill Savage, a fighter from the UK in Chiang Mai, tells me.

Those hours are precious. Like Claudio had mentioned, muay Thai fighters cherish any time for rest to keep up with their insane training schedules.

Thai fighter Sueadam "Black Tiger" Khongsittha starts the day at 5:30 AM with a run, then hits his gym, Khongsittha Muay Thai in Bangkok, for a few grueling hours of heavy bag work, knee strikes, pushups, sparring, and more. That hellish routine gets repeated later that day.

It's no wonder that fighters in training try to sleep any minute they can. It also explains how they can stay so shredded despite a diet of noodles and rice.

Of course, everything changes when a fighter needs to make weight. Cue starvation mode.

When you have to lose five to ten pounds before a fight, street food—or rather, most food—becomes off limits. Swiss native Markus Meier spent about four years fighting in Thailand. He remembers the process of cutting weight in the Kingdom as "the worst."