Joe Wicks "felt energised" after drinking his wife's breast milk.
The 38-year-old 'Body Coach' star caused a stir on social media last month as he drank the milk on his way to Taylor Swift's 'Eras Tour' concert, and the fitness guru left his wife Rosie startled by his actions.
Reflecting on the Instagram video on ITV's 'Good Morning Britain', he said: "I don't do that everyday. I never thought I'd be on 'GMB' talking about drinking my wife's breast milk.
"Look, it was a bit of fun. I was on the way to a concert and there was two options, throw it on the floor or drink it.
"And I had a really good night, I didn't have a drink, I felt energised and I felt pretty good for it."
'GMB' presenter Ed Balls was curious what it tasted like, and Joe admitted the milk had a "sugary vanilla" hint.
He added: "So basically it's like sweet milk. It's like sugary vanilla milk, it's really really naturally sweet.
"Like I said, I'm not drinking it by the pint, it was a shot and that was it."
Joe insisted he "can't be the first man to try their partner's breast milk", while Ed's co-host Ranvir Singh asked what his wife's reaction was.
He recalled: "I just said, 'I'm going to have a shot of this'. She was like 'Oh, what you doing'.
"I've had a go before and you know, I just thought it would be fun."
Joe and Rosie - who welcomed their fourth child into the world earlier this summer - also have Indie, six, Marley, five, and Leni, two, together.
Announcing baby boy Dusty's birth in June, he wrote on Instagram: "Today at 9.30am we welcomed our 4th baby into the world. A little boy weighing 7lbs 13oz.
"Rosie gave birth at home. The NHS midwives from St Peter's hospital were amazing.
"Rosie and the baby are both doing well and getting some rest."
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