He switched to a vegan diet in 2020 in a bid to lower his carbon footprint.

And Robert Downey Jr displayed the results of his plant based lifestyle as he strolled around the set of The Sympathizer shirtless on Sunday.

The 57-year-old actor plays multiple roles in the new HBO series and was seen made up as three different characters during the busy day of filming.

Looking good: Robert Downey Jr displayed the results of his plant based lifestyle as he strolled around the set of The Sympathizer shirtless on Sunday

Robert donned a curly brown wig for one look and highlighted his ripped abs as he went shirtless in a pair of navy jogging bottoms.

The Avengers actor has been looking noticeably slimmer after swearing off meat and dairy products.

He revealed he’d switched to a plant based diet while discussing his wife Susan, saying: ‘She is the greatest creative producer in the history of cinema and I make faces for cash and chicken. Even though no, I’m off chicken now.’

Wig off: The 57-year-old actor plays multiple roles in the new HBO series and was seen made up as three different characters during the busy day of filming

Susan said: ‘Not chicken anymore,’ as Robert quipped: ‘I’m going plant-based! For cash and legumes.’

Robert has invested in a number of plant based cheeses and meats and has also launched The Footprint Coalition, an organisation designed to help clean up the planet through the use of advanced technologies.

The actor was also seen dressed as another character in The Sympathizer, sporting a red wig with a receding hairline.

Svelte: The Avengers actor has been looking noticeably slimmer after swearing off meat and dairy products (pictured right in 2019)

Ripped: Robert donned a curly brown wig for the look and highlighted his ripped abs as he went shirtless in a pair of navy jogging bottoms

He was seen wearing a white T-shirt under a pink button-down shirt and a maroon coat as he walked through the set.

The Iron Man star completed his look with blue slacks and brown dress shoes for the day on set.

Robert – who shaved his head for the role – was also seen without any wigs as he relaxed on set in a baggy black hoodie and blue jogging bottoms.

Another role: The actor was also seen dressed as another character in The Sympathizer, sporting a red wig with a receding hairline

Looking good: He was seen wearing a white T-shirt under a pink button-down shirt and a maroon coat as he walked through the set

It was reported in November that Robert will play ‘multiple supporting roles as the main antagonists in The Sympathizer, all of whom represent a different arm of the American establishment,’ with the actor confirming in a December interview he is, ‘literally playing five different roles.’

The project was first announced back in July 2021, when Robert signed on to star in and executive produce the project, which is adapted from the 2015 debut novel from Vietnamese-American professor Viet Thanh Nguyen.

The series will follow a character simply known as The Captain (Hoa Xuande), a half-French half-Vietnamese spy, who has found himself in exile in Los Angeles in the final days of the Vietnam War.

Low-key: Robert – who shaved his head for the role – was also seen without any wigs as he relaxed on set in a baggy black hoodie and blue jogging bottoms

Chatting: The actor was seen chatting away to a crew member on the set of the new series

The Captain is described as, ‘a man of two minds and dual identities, the Captain is caught between conflicting loyalties, contradicting desires, and is ultimately forced to confront what it means to sympathize.’

Robert will be portraying the main antagonists, who all represent, ‘the American establishment,’ which will include, ‘an up-and-coming Orange County congressman, a CIA agent and a Hollywood film director,’ according to the original July 2021 report.

The cast also includes Fred Nguyen Khan as Bon, the Captain’s childhood friend, Toan Le as The General, the larger-than-life former leader of the South Vietnamese Secret Police, Vy Le as Lana, the rebellious daughter of the General and Alan Trong as Sonny, the idealistic former classmate of the Captain and now the editor of a Los Angeles Vietnamese-language newspaper.

One to watch: It was reported in November that Robert will play ‘multiple supporting roles as the main antagonists in The Sympathizer

Tucking in: Robert was seen enjoying a plate of plant based deliciousness on the set

Svelte: The Avengers actor has been looking noticeably slimmer after swearing off meat and dairy products

Yum: He revealed he’d switched to a plant based diet, saying: ‘I make faces for cash and chicken. Even though no, I’m off chicken now’

Sandra Oh also plays Ms. Sofia Mori, described as, ‘a liberated feminist who in the midst of a love triangle,’ Kieu Chinh as the Major’s mother and Nguyen Cao Ky Duyen as Madame, ‘the General’s wife and elegant and commanding matriarch.’

Robert will executive produce with his wife Susan Downey, with Chan-wook Park (Oldboy) creating the series while serving as showrunner and director as well.

While Robert has had small screen roles in the past including Ally McBeal, this will be his first major TV starring role in his illustrious career.

He also stars in the upcoming All-Star Weekend, directed by Jamie Foxx, though that doesn’t have a release date yet.

Keeping hydrated: Robert kept his hydration levels up as he sipped on a glass of water