Sunita Pattani realised her problem was out of control when she woke up one morning to find her husband was leaving her. "He said to me, 'It's not that I don't love you, but I can't be with you anymore. I don't know how to help you and I can't watch you doing this to yourself,' and then he packed his stuff and was gone within half an hour. I was just in shock. It was like somebody had moved the earth from beneath my feet."
Pattani wasn't ruining their life together by taking drugs, or having an affair, or making crazy demands on their relationship. She didn't drink, or gamble and she wasn't abusive. But she was suffering from a disorder that often goes unrecognised, even by its sufferers.
Pattani had binge-eating disorder, or BED. Even though it is less well-publicised than its destructive companions, anorexia and bulimia, BED affects the highest proportion of the population – around three per cent.
For Pattani, it began gradually. She dieted in her teens and when a diet failed she would fall off the wagon and indulge in sugary treats, but she maintained an average size 12 figure. Then, when she was 26, her nan passed away and she dealt with the grief by bingeing.
"I could not bear to go on another diet, but I had done it for so long, I didn't know how to eat sensibly. The more I ate the guiltier I felt. I went up from a size 12 to 20 in one year. I was ashamed, I was stuck, it was terrible. I stopped socialising and I stopped going out."
The over-eating can be extreme, with sufferers consuming up to 20,000 calories in one bingeing session. The National Institute for Clinical Excellence's guidelines state: "People have episodes of binge eating, but do not try to control their weight by purging. A person with BED may feel anxious and tense, and their condition might have an effect on their social life and relationships," but this does little to encapsulate the feelings of isolation and self-loathing that the disorder engenders.
Annemarie Louw, the unit head at the eating disorder treatment centre, Montrose Manor, says: "Binges lead to feelings of guilt about losing control, and the individual wakes up the following day thinking they should starve themselves as punishment or compensation for the binge the night before. The cycle starts again. This cycle accompanies strong feelings of being in control while not eating and guilt, shame and low self-esteem when bingeing."
Sian Renwick has struggled with binge eating disorder since university. She says: "I have never in my life had a stable weight for more than one month. My aim now isn't to be slim. I just want to be one weight, any weight, for more than a month. I've had it in my mind that I want this to be sorted by the time I'm 30, but the closer it gets the less likely I think it will be.
"I am quite introverted anyway, but I stopped going out because I was worried about not having control over what I ate. If someone asked, I would lie about why I wasn't eating, I'd say I was on antibiotics. I had 1001 excuses. I stopped doing most things. Eventually, the only person I was interacting with was my boyfriend, other than my family. He has always been amazing. He is incredibly patient but I can't talk to him as much as he would like me to. That does create a distance that's very hard to overcome.
"It's equally a factor with my parents. We can't talk about it, because they don't know how to ask and I don't know how to tell."
According to Emmy Gilmour, an eating disorders specialist and the clinical director of the Recover Clinic, secrecy and isolation are common effects of the illness. "Binge eating encourages you to isolate, because bingeing fuels that sense of shame and paranoia, and if it goes challenged, people feel they need to shut themselves off from the world. I meet a lot of women who have lived with binge eating into their forties or fifties and never tried to seek help.
"We are treating several people who are coming to therapy without their husbands' knowledge. We had a new admission this week, and for her just the experience of being in a room with other women who had experienced the same thing was the most amazing comfort."
"I honestly think that this form of eating is an addiction," says Nathan Bialek, who is 36 and has suffered from a cycle of dieting and bingeing since he was a young adult. "If I have a packet of biscuits, bag of sweets or any other treats in the house, I can't stop thinking about them until they are devoured."
Many sufferers describe the illness as an addiction or compulsion, and there is evidence to support the theory, showing that binge eaters' brains produce higher amounts of dopamine, a "reward" chemical, when they eat. But to consider the disorder as a purely physical illness belies the emotional trauma. "I would steer clear of the word addiction because it is a psychiatric condition," advises Mary George, a spokesperson for Beat, a resource for people seeking help for eating disorders.
"Calling it an addiction helps people to understand the compulsion you feel," says Renwick. "It is deeply ingrained and seductive patterns of behaviour, but it seems simplistic to call it an addiction, you can't get a patch for it!"
Another misunderstood element of this complex illness is that people who haven't experienced it tend to think a love of food and lack of discipline is the main cause. "One of the things people don't consider is bingeing is not just a reward, it can be punishment. When you eat something you know you aren't meant to eat, sometimes you don't even get that fleeting moment of euphoria, you feel shame and guilt and the fitting punishment is to eat until you feel sick because you don't deserve to be healthy," explains Renwick.
Generally, people are more sympathetic to people with anorexia, or even bulimia," says Gilmour. "There's a cultural view of people who are overweight as being greedy and thin people as a being vulnerable. We tend not to want to help or be associated with overweight people."
With all these challenges, it's easy to see why Pattani chose to bury her head in the sand rather than confront the problem. "It was a case of processing how did I go from someone intelligent to this mess," she says. She spent several months looking over her relationship with food which began with comfort eating and slowly escalated. Two years later, she has developed some principles on how to eat in a balanced way, and has written the book My Secret Affair with Chocolate Cake, which offers advice to others suffering with the disorder.
In the book, Pattani suggests tuning into your hunger signals and eating what you fancy as an antidote to the self-denial that's characteristic of the disorder. She also suggests charting different stages in your life to work out what bad lessons you learnt about food. She suggests making "affirmations" – positive statements about your body – such as "I am grateful that I have healthy lungs". Visualisation, pampering time and writing your feelings down in a journal will all help with your self-worth, she says. "Know it's OK to have a good cry, or ask for a hug when you feel the need," she writes.
Pattani is now back with her husband and is on the road to recovery, but others, such as Renwick, are still battling with the illness. "It's a bloody stupid way to waste your life," she sighs.