In December 2016, Gigi Hadid was crowned International Model of the Year at the Fashion Awards, after a season walking for the likes of Marc Jacobs, Versace and Tommy Hilfiger and gracing the covers of countless glossy magazines.
Days later, however, the now 23-year-old star revealed that despite her jet-setting lifestyle, athletic physique, and seemingly perfect lifestyle, she'd been secretly battling a debilitating thyroid condition.
'My metabolism actually changed like crazy this year,' she revealed during a Reebok panel in New York.
'I have Hashimoto's disease. It's a thyroid disease, and it's now been two years since taking the medication for it.'
So, what is Hashimoto's Disease?
The Mayo Clinic explains, it's a condition in which your immune system attacks your thyroid gland – that small gland at the base of your neck below your Adam's apple, which produces hormones that coordinate many of your body's functions.
Inflammation from Hashimoto's Disease, also known as chronic lymphocytic thyroiditis, often leads to an under-active thyroid gland (hypothyroidism) with symptoms including: fatigue, increased sensitivity to cold, muscle weakness, depression and memory lapses.
While there's no definite causes for the disease, it's widely recognised that women are more likely to suffer from it than men, and it's more likely to develop among the middle-aged.
As a result, ELLE UK spoke to three women to find out what it's really like to live with the condition:
Amy Perry, 23, learning support assistant
'Hashimoto's Disease and Hypothyroidism runs through my Dad's side of the family so it wasn't exactly a surprise when I was diagnosed with it aged 13.
I'd been suffering constant tiredness and a lack of concentration at school for months prior to diagnosis. My doctors were convinced I had anaemia, but fortunately sent me for a blood test which revealed that my thyroid was underactive.
My Dad and I often joke that the condition feels as if you've got a wet blanket on your head all the time. It makes your head feel cloudy, tired and it doesn't matter how much you sleep or eat, you can't get rid of the foggy sensation.
As a result, I developed anxiety and struggled to cope with social situations. Whenever I was in a busy shopping centre or at a party, it was as if I was watching it from afar and soon felt sick and panicked. I was on antidepressants for a few years, but came off them because I wanted to manage my illness on my own. Occasionally I feel down when I see my friends heading off to the gym together, as I'd love to go, but I've come to learn that my normal isn't everyone else's normal.
When most people come back from work, they can concentrate on other things or go out on a Saturday, but that's a no-go for me. Socialising is so difficult and on occasions when I've tried to go out at the weekend, I take days to recover. As a result, I don't drink and avoid caffeine as much as possible. Too much caffeine can cause problems with the endocrine system and make me panicky.
It's claimed that gluten increases inflammation of the thyroid, so I've taken it out of my diet, as well as meat. It's a case of seeing what I'm able to manage at a time, and making sure I'm as rested as possible at weekends.
'I often joke that the condition feels as if you've got a wet blanket on your head all the time'
My weight fluctuates constantly as a result of my changing thyroid levels. When I'm hypothyroid, I'm on medication that makes me gain weight, but the next test can find I'm hyperthyroid and I start to lose weight. My mum says she can see it in my face when I'm not feeling well.
People generalise thyroid conditions a lot and presume sleep is the cure. Raising awareness is essential.'
Natalie Highett, 35, cardiac associate technician
'Sixth months ago, you wouldn't recognise the person I was, compared to who I am now; an ultra marathon runner at the gym three times a week, I cycled to work, and went swimming twice a week. As a vegan who woke up at 5.30am every morning, I was the fittest and healthiest I'd been in my life.
That was until September 2017, when I woke up one day with hideous anxiety. It was like I had transformed into someone else. Initially doctors thought my blood tests were normal, despite the fact Hashimoto's Disease runs in my family, and I was given antidepressants. A few weeks later, another test found I was hypothyroid and I was prescribed Thyroxine [a medication used to treat the thyroid gland].
While my anxiety and depression cleared, I've gone on to suffer from sore joints – it's like my ankles constantly feel sprained – insomnia, fatigue, and hair loss. I ended up shaving half my hair because it was such a tangled, matted and dry mess. I've also gone from 53kg to 66kg. It's knocked my confidence and made me feel so isolated. I no longer see my running friends, colleagues or fellow mums at the school gate.
On one occasion, I remember being in so much pain on the sofa that I couldn't get up for my painkillers. I had to call my husband at work and ask him to pick up the children from school because I couldn't. Going from being an active person to someone who can't even walk the dog, it's frustrating. I promised my daughter I'd take her ice skating and trampolining in the summer. Who knows if that'll be possible.
I now take daily painkillers, Vitamin B and D tablets and have ruled out alcohol from my diet completely – it makes me have what feels like a five-day hangover afterwards if I dare touch it.
Planning for the next few months is hard. I don't know whether I should buy new clothes as a result of my fluctuating weight or book our usual holiday at a cottage in the countryside because I don't know what the future holds.
I remember being in so much pain on the sofa that I couldn't get up for my painkillers
I've learned the disease affects people in different ways. I think it's probably affected my life more because I was so fit before hand. In the case of Gigi Hadid, who is regularly seen flying across the world and modelling, I presume her condition is managed as a result of her treatment. Private health care, access to the best medicines and catered diet would all have an impact on an individual's symptoms.'
Katrina Andrews, 26, dental nurse
'I was diagnosed with Hashimoto's when I was 12-years-old. I'd just started secondary school but my symptoms - tiredness and lack of energy - were initially thought to be a result of too much school work.
I remember asking my doctors and family members if it was normal for girls to have Adam's apples, as I could feel a lump in my throat, but they just thought I was going through puberty.
After a few months, I knew something wasn't right. I'd regularly suffer from migraines and be off school, would sleep all weekend and sport was out of the question.
At the time, so many people thought it was because I was lazy or didn't like school but I remember explaining to my Mum that it was a different sort of tiredness. Even now, I regularly get called lazy because I have to sit down a lot.
A new doctor finally said my symptoms sounded like I had the disease. A blood test and scans on my throat to check if I had cancerous nodules, confirmed his suspicions of an underactive thyroid which led to the disease. It was pretty scary at the time.
While medication helps, I've learned to become extremely organised.
As a teenager, I never went clubbing because I couldn't stay awake past 10pm. I don't feel I missed out as such; I just didn't have the energy. I originally wanted to go to university, but changed my mind for fear of not having the support from my family. Fortunately my job as a dental nurse has fit perfectly around my life, enabling me to have time to rest if necessary.
I regularly get called lazy because I have to sit down a lot
The only way to describe a flare up from the disease is that it's like having the flu. The second I wake up in the morning, I question 'do I have the energy to get out of bed?'
I have a five-year-old so I don't have any choice but to get on with it - I could sleep for 10 hours and still feel as tried. Stress, migraines, deep aches and pains have become the norm.
I take Vitamin D supplements, B12 deficiency injections and migraine medications, ensuring I rest as much as I can.
As I've got older, I've found it difficult to lose weight. I wanted to lose weight for my wedding and even tried Weight Watchers, but I simply don't have the energy to go to the gym – it's incredibly upsetting.
The vast majority of people don't understand or have awareness of the condition, presuming a sufferer is lazy or uses the disease as an excuse not to socialise. Often, GPs don't even take you seriously when you say you're tired. Hashimoto's Disease is an invisible illness.'