I’m having dinner with a group of friends. I’ve invited people round so I can cook. It makes me feel more in control of the situation.

I’ve spent hours preparing food, and I’ve given myself the smallest portion. I’ve got scrapings from the bottom of the pan while everyone else has a hearty meal in front of them. As I eat, I feel my body expanding out of all proportion. I am corpulent, huge, disgusting. I feel the fat on my stomach, thighs and buttocks rippling, stretching my clothes.

I know, on a logical level, that I’m not the biggest person in the room, but my brain is telling me with utter certainty that I am taking up more space than anyone else.

This is body dysmorphia, or body dysmorphic disorder (BDD). It’s a mental health condition characterised by extreme preoccupation with the body. Sufferers engage in constant checking, obsessive thoughts about different parts of the body, and taking excessive time perfecting their appearance. BDD covers things like skin picking to make the skin ‘smooth’ and preoccupation with ‘flaws’ that are often unnoticeable to others.

I’ve struggled with body dysmorphia since I was 13 years old, meaning that over half of my life has been spent checking my body and seeing things that others don’t. The idea that I can’t even trust my own eyes is terrifying and makes me doubt my ability to engage in rational thought processes.

According to a study from Chemist-4-u, one in 20 people suffer from BDD. It is a serious condition that can impact on relationships and ability to work. BDD can result in depression, self-harming behaviours and suicidal thoughts.

Kate, 29, says: “My experience is that I’m obsessed with my appearance and spend far too much time in front of the mirror pulling and poking bits of my stomach, almost in a bid to make it shrink. I find it disgusting and it makes me so self-conscious and paranoid.

“And I know it’s often completely irrational because I’ll look back at photos and be like I’m so thin there but I can vividly remember that day feeling like my stomach was huge.”

Body dysmorphia often accompanies serious eating disorders like anorexia and bulimia. Clare, 33, suffers from anorexia, so BDD is often posed as a symptom of her disorder.

She says: “For me it’s a question of what came first as I remember struggling with my body and being told that I was seeing things that others weren’t seeing before binge eating and anorexia were diagnosed.

“BDD impacts me terribly every day. Walking past a mirror shop window or anything which I can see my reflection in is extremely anxiety provoking and leaves me in tears daily and I have many checking rituals which are also emotionally exhausting.”

Unfortunately, body dysmorphia is often taken less seriously than it should be, and even the NHS website states that it can be difficult to seek help for BDD. Symptoms are unlikely to go away without treatment and may worsen if left unchecked.

Keith McNiven, founder of Right Path Fitness, says: “While body dysmorphia doesn’t discriminate, young adults and teenagers especially suffer from it, as they’re getting used to their bodies and trying to live up to unrealistic ideals (especially with the rise of social media, where celebrities, influencers and the like are constantly posting beauty selfies of themselves – many of which are modified with filters or through retouching).”

I’m convinced that my body dysmorphia started when I saw a set of holiday pictures of myself and started comparing them to models. In the early 2000s, ultra-skinny models and the ‘heroin chic’ look were ubiquitous on catwalks, and my 13 year old eyes warped as I gazed at them.

Even with the increasing presence of body positivity Instagram accounts and more diverse bodies used by some (not nearly enough) brands, the standard of beauty that we measure ourselves against is still largely unattainable.

Whether this is the stick-thin Victoria Secret model or the surgery-enhanced body of a Kardashian, women can be left feeling inadequate, dissatisfied and worthless.

These feelings all feed into a toxic culture where body dysmorphic disorder is increasingly common, for men as well as for women. BDD can be treated with cognitive behavioural therapy (CBT) and antidepressants, namely selective serotonin re-uptake inhibitors (SSRIs).

However, we need to see a greater cultural change to prevent new cases of BDD and allow all people to feel at peace with their own bodies.