Three couples reveal how losing weight also meant losing their marriage

Cheryl Blakelock, Jo Harrison and Dave Guthrie have got two things in common.

They have each shredded a serious amount of weight, and have also lost their relationship in the gruelling process as well.

With every kilo lost, the three shedders believed they would earn just a little bit more confidence and attractiveness with their new found figures, but the fantasy of having a better life slim doesn't always match the reality - as they each found out over time.

So why does the search for a slimmer, happier life often lead couples to breaking point - and consequently, a broken marriage?

Cheryl Blakelock was a size 30 at her biggest when she made the decision to lose some serious weight.

Being married for 25 years, and reaching a size 6 after some serious weight loss -
never did she think her life would be so affected by her changing dress size.

"While I was overweight, I was easily controlled. I didn't really want friends, and I didn't really have friends," she said in UK documentary I Lost Weight and My Husband.

"I lived my life for my children. I didn't want to stand out, I wanted to blend into the shadows."

But Cheryl admitted that with every kilo she disposed of, more of her true personality came to light - a change which she believes lead her husband astray.

"It's like being an onion. As the fat comes on, it encloses your personality, and as it comes off - it exposes who you are. When the weight came off, I look at everything in a totally different light."

While Cheryl felt like a new woman, her husband found the drastic change hard to deal with.

"He couldn't cope with me becoming a person and actually answering back and gaining confidence. He just slowly lost control, and that's when he started looking for another woman."

Cheryl recalled a text coming through on her husband's phone which he had left at home.

She decided to read it, and that's when everything started to unravel.

The nature of the text convinced Cheryl her husband was having an affair, but what came as more of a shock was when she saw the woman - who was a size 24.

"I remember getting out of the car, and I hadn't heard much about this woman at that point apart from the fact she was younger than me," Cheryl said.

But then when I seen the size of her, she was a size 24 and at the time when we decided to split, I was a size 10. She even dressed the same as I used to dress."

Cheryl felt she had been replaced by a pre-weight loss version of herself.

"I spent 22 years being overweight, and I couldn't be that woman again," she declared.

"Anybody who says to me that they're the same person fat as they are thin. I'd call a liar.

"Losing weight changes your whole life. It changes you, it changes the effects on people. Don't think your life is going to be the same because it's not."

Cheryl isn't alone, because for many people who have drastic weight changes - it spells out major problems for relationships.

A study conducted jointly by North Carolina State University and University of Texas at Austin sought to answer the question as to why relationships break down after one party loses weight.

Researchers sent an online questionnaire to 21 couples in which only one partner had lost at least 13kg.

While most couples that completed the study were straight and married; all lived together.

The study showed that in 67 per cent of cases, the one who lost the weight was female.

Of the couples quizzed, each member independently answered questions about the effects of the weight loss on their health, their partner's health, and on other aspects of their relationship.

The result showed that there was a "dark side" to weight loss, if both partners were not on board with enacting healthy changes

"People need to be aware that weight loss can change a relationship for better or worse, and that communication plays an important role in maintaining a healthy relationship," Dr Lynsey Romo, an assistant professor of communication at NC State and lead author of a paper on the research said in 2013.

The researchers revealed that after the weight loss, the couples' communication usually changed for the better.

But the partner who lost weight was more likely to talk about healthy behaviours, in an attempt to inspire his/her partner to try a healthier lifestyle.

But in a large portion of cases, weight loss resulted in negative communication - because some partners who lost weight would nag their other half, causing tension in the relationship.

With a fresh outlook, changed priorities and a new lease on life - Mrs Harrison found out the hard way how significant weight loss played a detrimental impact on her 11-year marriage.

Going from 158kg to 95kg in 2013, Mrs Harrison realised she needed to change at her 30th birthday.

"The crunch came when I was 30, and we had to hire a wheelchair because I just couldn't physically cope with the walking," she admitted.

"I thought if I lost weight it would be great because we [Jo and her husband Darren] would have this fantastic life together and it would be wonderful, and fun and we could be intimate.

"But the reality of it is we don't kiss or cuddle. He sleeps on one side of the bed, and I sleep on the other."

Her husband Darren admitted at the time that by his wife going on a diet, their common interest in food had gone - meaning the pair drifted apart.

"So you have to work hard to grow back together," he said.

Food became Jo's comfort when she found out she was going to have difficulties having children.

"Food was the way I was able to maintain a day to day function of my life," she said.

"We'd go out for pizza, or out for a curry. We got engaged at the curry house actually."

But with the food grew a different person, and a person Mrs Harrison wanted to change for good.

"I'm a different person to what I was when I married him [Darren]," she said.

"I think I am slightly resentful that he hasn't embraced this new change me as much as I would've liked him to."

While the weight loss gave Mr and Mrs Harrison children, her new lifestyle meant the one thing they enjoyed together - unhealthy food - had to go.

"Once you take that away, your common interest, which must've been food which has gone, then I guess that's where the cracks started from," Mr Harrsion said.

David Guthrie walked out on his partner Rachel after she failed to lose weight while he shed 50kg.

"My weight loss is more important now than my relationship," he said at the time.

David admitted that the highs that came with losing weight meant he kept pushing himself to shed more and more kilos.

"What changed our relationship is that I started getting attention, and people started commenting on my weight loss and how good I was looking," he said.

"This only spurred me to go on further ... it's almost like now I can't enough of the attention."