Jeremy Piven's strict training regime for his new movie meant he could only drink water on a night out with magician Dynamo.
The actor stars as tap dancer Harold in the upcoming film The Performance, alongside Robert Carlyle and Adam Garcia.
Celebrity trainer Ruben Tabares has revealed that Jeremy, 56, got into peak fitness to handle the intense physical demands of playing a dancer and the numerous takes that shooting the film involved.
"He's like the rest of us, he just likes to eat food," Ruben smiled. "When you have to restrict the number of calories, food becomes a little bit blander. And you have to look at things you can't have, like sauces.
"I went to dinner with him and I invited Dynamo and some other people, and we all had something to eat apart from Jeremy who'd already eaten his calories for that day. And he just sat there and had water while the rest of us were stuffing our faces."
Watching his dinner companions chow down didn't faze the triple Emmy winner though, whom Ruben praises for his dedication.
"You'd be surprised how similar an actor and a world champion boxer are in terms of their mindset," said the wellbeing expert, who helped David Haye become a world boxing champion and has also worked with Amir Khan.
Ruben added supplements into Jeremy's carefully tailored nutrition plan, using the two blends he's created in partnership with health and beauty brand The Organic Pharmacy; Performance and Longevity.
Both are made with only natural ingredients, including ginseng and beetroot in Performance, which boosts aerobic endurance amongst other benefits, and turmeric root and B12 in Longevity, designed to reduce muscle fatigue and help fight tiredness.
"(Supplements were) very important. When you're decreasing the amount of food that you're having then you're also decreasing the amount of vitamins and minerals," he shared. "So you need to make sure that you're getting in all your background nutrients; vitamins, minerals, enzymes, probiotics and prebiotics."