Insider got the scoop on Chris Hemsworth’s grueling dehydration process from his longtime trainer Luke Zocchi. Hemsworth uses this process in the four Marvel movies he’s shirtless as Thor.
While promoting the lifestyle app, Centr, which he and Hemsworth founded, Zocchi told Insider the details. Hemsworth gradually increases how much water he’s drinking a week before shooting a shirtless scene. Then, a day and a half before the call time, he stops drinking water.
“We start with three liters and everyday increase by one liter, and then by the end, he drinks seven liters of water,” Zocchi said. “Then around lunchtime before the scene, we cut water completely. This is by no means a healthy thing to do, and I wouldn’t recommend that anyone else do this.”
Zocchi said Hemsworth will simultaneously carb-cycle to prepare for the scenes. Leading up to filming, he depletes his body of carbs. Then, on the last two days of filming, he eats 40 grams of carbs every two hours. This part of the cycle happens in the last two days before call time. Why do they do this? Zocchi explains that the process replenishes the glycogen in Hemsworth’s muscles after they’ve been cleared out of all their fluid. In turn, this causes them to look harder and denser than they would typically look naturally.
“So at the start of the day (before the scene) I would give him a sweet potato and brown rice, then closer towards the day I would give him rice cakes. And then half an hour before he stepped out I gave him snickers and a handful of lollipops, and he doubled in size by the end of the day,” Zocchi said.
Additionally, Hemsworth spends the last two days before filming doing high-rep, low-weight lifting workouts to build a pump in his muscles, Zocchi said.
“You’re basically trying to look as hard and as dense as you can with your muscles and take all the fluid out of your body, and take out as much fat as you can,” Zocchi said.
Zocchi said he was first introduced to this technique from studying competitive bodybuilders. He went on to say he’s seen contestants faint due to dehydration before and after competitive events. Sadly, according to Men’s Health, Mohammed Benaziza, a competitive bodybuilder, died at the age of 33 in 1992 from dehydration causing heart failure.
As for the actor, Zocchi said that Hemsworth has experienced common symptoms of dehydration. This includes a headache or noticeably less energy after his routine of dehydration and carb-cycling.
Besides the obvious health concerns, this routine has the potential for visible downsides as well. Dr. Rand McClain, chief medical officer of the sports medicine clinic LCR Health, told Insider about this drawback. Apparently, doing this type of dehydration process can cause muscles to appear smaller in the future, McClain says.
McClain says dehydration can disrupt the low salt to water ratio in the body, which would cause muscles to flatten and shrink in size, which is “the opposite of what they are trying to do.”
Also, dehydrating the body after drinking a lot of water can send a signal to the body’s cells that not enough sugar is in the blood, which can make a person hungrier and lead to more calorie consumption which could be converted to fat, McClain said.