While the actor, 37, may appear to be the epitome of confidence, her interview with Sports Illustrated Swimsuit as the outlet's new cover star reminds us we don't always know what someone is dealing with privately.
"I have body dysmorphia," she said said in a video.
"I don't ever see myself the way other people see me. There was never a point in my life where I loved my body, never ever."
Fox had her career breakthrough in her role in Transformers in 2007, but body image had been on her mind long before that.
"When I was little, that was an obsession I had, of like 'but I should look this way'. Why I had an awareness of my body that young? I'm not sure, and it definitely wasn't environmental because I grew up in a very religious environment where bodies weren't even acknowledged.
"The journey of loving myself is going to be never-ending I think."
What is body dysmorphia?
The mental health condition Fox experienced is called body dysmorphic disorder (BDD). Sufferers typically spend a lot of time worrying about flaws in their appearance, according to the NHS. It can seriously affect everyday life, causing issues with work, social life and relationships.
These perceived flaws are often unnoticeable to others, as it is more about how someone sees themselves. It does not, however, mean you're vain or self-obsessed, and it can cause a great deal of distress.
Anyone of any age and gender can have BDD, but it's most common in teenagers and young adults.
Body dysmorphia symptoms
According to the health service, you might have BDD if you:
worry a lot about a specific area of your body (particularly your face)
spend a lot of time comparing your looks with other people's
look at yourself in mirrors a lot or avoid mirrors altogether
go to a lot of effort to conceal flaws – for example, by spending a long time combing your hair, applying make-up or choosing clothes
pick at your skin to make it 'smooth'
It can severely affect your daily life, sometimes leading to depression, self-harm and suicidal thoughts, but support is out there.
Help for body dysmorphia
While BDD can have a big impact, there are ways to help manage it and recover.
"People often come to me with body dysmorphia – particularly teenagers – and I always challenge their negative beliefs to try to put more positive ones in place," explains psychotherapist, Christine Elvin, referring to cognitive behavioural therapy (CBT) techniques.
"In a world of Instagram filters and apps that change the way you look with the press of a button, it’s important for us to remember that airbrushing and photoshopping exist and for us not to be blinkered by what we consider the ‘perfect’ body".
If you think you have BDD, the first step is to speak to your GP, who will either offer treatment themselves or refer you to a mental health specialist.
Depending on the severity of your symptoms, treatments may include:
cognitive behavioural therapy (CBT`), on your own or in a group
a type of antidepressant called selective serotonin reuptake inhibitor (SSRI)
CBT together with an SSRI
Elvin, who practices CBT counselling with her clients, adds, "I look to find out what triggers body dysmorphia and work from there. It can be anything from low self-esteem, unhealthy beliefs growing up or bad experiences at school.
"Try looking for five things that make you feel good about yourself each day. You might be surprised at what you find written on those pages."
Body dysmorphia causes
Although anyone can be affected by the condition, these causes can make you more susceptible:
genetics – if you have a relative with BDD, obsessive compulsive disorder (OCD) or depression
a chemical imbalance in the brain
a traumatic experience in the past – if you were teased, bullied or abused when you were a child
There is nothing to be ashamed of if you think you might have the condition, and speaking to your GP is crucial for getting the help you need.
You can also refer yourself directly to an NHS psychological therapies service (IAPT).
The Body Dysmorphic Foundation has a useful directory of local and online BDD support groups.
If you need someone to talk to, you can call Samaritans any day or time on 116 123, or email firstname.lastname@example.org for a response within 24 hours.
Watch: Sam Smith: 'What should a pop star look like?'