Chris Pratt is taking his health regimen to biblical proportions. Literally.

The actor, 39, updated Instagram followers on his latest diet routine: the Daniel Fast, a combination of fasting and prayer inspired by the Bible.  

“Hi, Chris Pratt here. Day Three of the Daniel Fast, check it out,” Pratt said in a now-expired Instagram story video. “It’s 21 days of prayer and fasting.” 

A website for the Daniel Fast explains it's a "partial fast where some foods are eaten while others are restricted. Most people use this method of fasting for 21 consecutive days."

Participants are restricted to drinking only water and eating only foods that have grown from seeds, like fruits, vegetables and grains. The name is inspired by the Old Testament prophet Daniel, who limited his diet to vegetables and water to be able to cleanse his body and better focus on a spiritual connection to God, leaving behind distracting indulgences like meat and wine. 

Pratt noted the end of his three-week program would align with the beginning of his 'Lego Movie 2' press tour and joked about how it might affect his interview skills.

“It’s going to coincide also, coincidentally, with the ‘Lego Movie 2’ junket. So, by the time you see me, I’ll probably be hallucinating,” he said. “Stay tuned.”

The actor recently opened up about how he was struggling to stay fit during the holidays. 

"These last couple of months, I have just not been that motivated to work out. And I’ve been eating," he said on an Instagram story in December. "And I know it’s winter and it’s holiday season. This morning I woke up and I’ve determined that I’m going to get on it. And I don’t want to, but I’m going to do it, I’m going to start it today."

"Let’s motivate each other," he continued to his followers. "Social media stuff can be so ugly and so nasty and it can make us hurt one another but I’m trying to motivate ya."

This article originally appeared on USA TODAY: Chris Pratt reveals he's fasting for 21 days with Bible-inspired Daniel Fast