Chris Hemsworth does a dehydration routine before filming a shirtless scene, his trainer says.
He ups his water intake during the lead-up to filming, then drinks no water a day and a half before call time.
His trainer says he "wouldn't recommend" the process, but they have found it helps make his muscles look denser and harder.
Every shirtless scene Chris Hemsworth shoots as Thor has a grueling dehydration process behind it, according to his longtime trainer Luke Zocchi.
Hemsworth has appeared shirtless in four movies in his role as Marvel's Thor. A week before he shoots a topless scene, Hemsworth gradually increases his water intake, then stops drinking water a day and a half before call time, Zocchi told Insider while promoting the lifestyle app, Centr, which he and Hemsworth founded.
"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. He depletes his body of carbs in the week leading up to filming, but then eats 40 grams of carbs every two hours in the last two days before call time. Zocchi said this process replenishes Hemsworth's muscles with glycogen after draining them of all their fluids, which makes them look denser and harder than they would 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.
Hemsworth also 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 says the routine gives Hemsworth headaches and low energy
Zocchi said he learned about this process from studying competitive bodybuilders, but added that he's seen contestants faint before or after competitions due to dehydration. A competitive bodybuilder named Mohammed Benaziza died at the age of 33 in 1992 from heart failure due to dehydration, according to Men's Health.
Zocchi said that Hemsworth has gotten a headache or felt less energetic after his dehydration and carb-cycling routine, which are common symptoms of dehydration.
There are also potential aesthetic downsides to the routine as well, according to a doctor. Doing this type of dehydration process can cause muscles to appear smaller in the future, Dr. Rand McClain, chief medical officer of the sports medicine clinic LCR Health, told Insider.
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.
Read the original article on Insider