If there is one thing Rob Lowe is known for it's his ageless good looks and super-toned physique.
If you look back on his photos from his mid-20s to 30s, you will find that not much has changed — the 55-year-old is still a lean, fresh-faced man in peak physical condition.
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He even says so himself but in a more humbling way.
"I, 100 per cent feel better than I have ever felt," he tells news.com.au in an exclusive interview, "and for me that started in my 40s and from then on until now I feel each year has been the best iteration of myself."
But like anything in life, Lowe emphasises that nothing comes for free. He has had to make a few sacrifices along the way.
For the actor, who landed his first major TV role in 1979 and whose breakthrough came in the 1983 film The Outsiders, it was revamping his lifestyle choices — ditching certain foods and beverages.
In fact, he hasn't touched alcohol for nearly 30 years, and there's a big reason why.
"I felt like in my 20s I probably enjoyed it a bit too much," he said.
"I learned that when I was not drinking, I liked who I was better as a person and then there's the added benefits of feeling and looking better."
After reaching idol status, Lowe was training with the UCLA track team around the same time his love of partying and alcohol became an addiction.
Known as one of the '80s Brat Pack, Lowe trained like crazy to reassure himself he didn't have a problem. But once he hit 26, he managed to get sober, with exercise playing a new role in his life as alcohol took a back seat.
'BOOZE IS BRUTAL'
The Golden Globe-winning actor committed to sobriety on May 10, 1990, and this year marks his 30th anniversary.
"It became an outlet for all of the tension, stresses, compulsivity," he told Oprah Winfrey in 2014. "I funnelled the addiction, frankly, into that."
He tells news.com.au: "I don't drink and haven't for 30 years now and that's such a competitive advantage for me — just the calories alone from booze are just brutal and it just kills you.
"But all of this stuff is the stuff you've got to want to change. There's no free lunch."
In his 20s Lowe became aware of what he was consuming; however, it was until he reached his 30s that his lifestyle changed completely.
"It's that moment when you wake up and realise 'I can't eat like I used to' and that day comes for all of us."
Instead, he did something about it.
"Then you just have to make a choice with what you want in terms of quality of life, your energy and how you look and feel," Lowe said.
"You have to make some adjustments and that's what I did."
Long gone are the days when Lowe used to get away with eating endless amount of greasy takeaway foods like pizza.
"You can kind of get away with it in your 20s and 30s, but getting into your 40s and 50s, you can't hold onto to those habits and expect to be the fittest, best version of yourself," Lowe said in his role as Atkins brand ambassador.
"When I got into my 30s, I was at that point we all get to: 'Oh there's a fork in the road here, I can either be dad bod or try and hang onto my youth'."
So he did the latter.
"I began eating in the Atkins style (low-carb lifestyle) without knowing I was doing it," he said.
"I was probably in my mid 30s when I really cut the carbs, having very little pasta and bread and focusing more on proteins and the right fats – my new thing is trying to manage the sugars because I still have a sweet tooth."
While the diet has been criticised for advocating a drastically reduced carbohydrate intake – even being compared to the likes of the keto diet, a similar low-carb meal plan – Lowe says its flexibility continues to make it desirable.
"Atkins is the original keto, it's just more flexible," he says, admitting "keto is very hard to maintain".
The Atkins diet first devised in 1972 by Dr Robert Atkins but was made famous by his second book, Dr Atkins' New Diet Revolution, in 2002.
Since then the high-protein diet has gained plenty of attention with about three million people in the UK alone having tried it in 2003.
In the US, one in 11 was reportedly on it attracting the likes of celebrity fans including Jennifer Aniston, Demi Moore and Catherine Zeta-Jones.
"I find this (Atkins) really easy to maintain," Lowe said. "It's not all red meat, bacon and eggs, it's actually a more balanced approach. You're eating things like lean proteins and vegetables. You're eating foods high in fibre, you have your fats like olive oil, avocados and fruits.
"If it were a diet, I couldn't do it because it wouldn't be sustainable. It truly is a lifestyle, and I don't feel like I'm missing out on anything."
For a man in his mid-50s, Lowe said he had never felt better, with his new and improved lifestyle giving him a tremendous amount of energy.
"The low-carb lifestyle takes away all the after-meal tiredness and grogginess you sometimes get. I feel energised throughout the day, lighter on my feet and way more mentally focused," he said.
And for someone who trains nearly every day, he needs it.
'I HAVE TO BE ACTIVE OR I'LL GO INSANE'
If he's not on-set filming a movie or TV show, you will find Lowe either surfing, hiking, playing tennis, golf or on his peloton bike.
His style of training varies from interval exercises with weights to mixed cardio.
Food and fitness go hand-in-hand for the actor, who says if you are living life right, the older you get, at least spiritually and mentally, you should be feeling the best you have ever felt.
"I am doing something every day. I do it for my mood and my head. I have to be active or I go insane," Lowe said, adding it's important to make fitness a part of your everyday life.
"It doesn't have to be the gym or a treadmill – you just got to keep moving and get your sleep right too."
If Lowe is working on set, which he is now, currently filming his new TV show 9-1-1: Lone Star, you will catch him training on his lunchbreaks.
"I find that actually gives me tonnes of energy for the day, and that's why I am forever grateful for Atkins bars because I can just have one of those and get into the gym and I am good to go," he said.