The former teen model, who shot to fame as alien seductress Sil in the Species films, is a busy mum to two teenagers, but she still makes time to take care of herself.

Aside from drinking water throughout the day and exercising in the hills above Hollywood and beyond, Natasha has a tried-and-tested formula for beauty success - and she's sharing it for the first time.

"I also use Vitamin C Serum on my face every day and have for years, combined with SPF of 30 or more daily," the actress tells WENN. "I get monthly facials by a genius facialist who works out of her home, called Donna Lee, and I swear she takes years off me when I go regularly.

"Also now that I'm in my 40s, for a couple months of the year - usually in the fall - I use a Retinol product that sloughs off a few extra layers."

Staying fit is a big part of Natasha's life too, and she combines hiking and hot yoga with Pilates to sweat off any gained weight.

"I sometimes work with a trainer, then take breaks," she adds. "I'm really not a fan at all of the gym so it's tough for me to stay on that path too long. I'm really an outdoorsy person, so if it's mountain biking, or something that makes it feel like I'm not exercising, that's always my preference.

"And I try to eat well and clean. I certainly feel so much better when I do, however sugar is a tough one for me; I'm sort of always tempted by it and struggling to avoid it. Otherwise, I love to cook and I do about five days a week. I certainly like my occasional glass of wine, I've been blessed with the moderation gene, though."

Natasha has more of a weight battle than some Hollywood stars after learning she suffers from auto-immune condition Hashimoto's disease.

"I was diagnosed with a thyroid disorder a few years ago and it turns, out upon further investigation, that it was Hashimoto's disease," she explains. "It's an auto immune disease that can wreak havoc on your body in many different ways, but one of the more visible side effects is weight gain.

"As a result, I don't burn off extra calories easily. I try quite hard to maintain even the size I'm at now, which by Hollywood standards is large."

And when Natasha isn't working, she's not averse to using a little cosmetic help to give her face a fresh look, revealing Botox is her go-to - but she refuses to get carried away.

"I get a little Botox from time to time, particularly when I'm not working," she confides, "but I like to have full range of motion of my face when I'm on camera!

"I'm very sensitive to it and really had a bad brow droop once and no expression, which is not fun when you're trying to do an emotional scene and the only way of telling if you're upset is tears and your voice."