Valentine's Day: Love Island's Jack Fincham on how being with Dani Dyer led to unhealthy lifestyle

Love Island 2018 winner Jack Fincham is on a 12-week training programme and will take part in a celebrity fight in April

Do you find yourself eating more and exercising less when you're in a relationship? Or do couples who train together, stay together?

Love Island winner Jack Fincham was shocked when a nutritionist told him his body mass index put him in the 'obese' category after he moved in with girlfriend Dani Dyer.

"It's strange because when you think of obese you think of someone who can't move. But I can go on a run - I'm fit," the 27-year-old told BBC Get Inspired.

"I put on a bit of weight. I've never been fat, I'm not fat now, but I was just a bit slow."

Although he wouldn't class himself as obese, Jack says it gave him a wake-up call to improve his diet and lifestyle.

With Valentine's Day approaching, BBC Get Inspired asks whether it's harder to stay healthy when, as they say on Love Island, you're "coupled up".

Is it harder for couples to stay fit and healthy?

Jack and Dani rose to fame last summer after winning the reality show Love Island

More than 3.5 million watched straight-talking Jack share the £50,000 prize money with now-girlfriend Dani, 23, last summer.

Surrounded by contestants who boasted more eight packs than an off licence, Jack says he was just a "normal" guy who "wasn't ripped nor fat" in the Love Island villa.

After winning the show, his new-found fame led to a busy schedule.

Not only did Jack inherit a potential father-in-law in hard-man actor turned royalty Danny Dyer, the former pen salesman tried his hand at presenting at the National Television Awards and is starring in spin-off Jack & Dani: Life after Love Island.

However, it was more than work that led to Jack neglecting diet and exercise.

"There have been times when I should probably get in the gym but if Dani goes 'shall we get a curry and stay in and watch a film?' I have to think about what's more interesting," he said.

What do the experts say?

Jack's hoping to continue with his new boxing training regime after his bout in April

Kimberley Wilson is a psychologist who specialises in the relationship with food, and runner-up in the 2013 Great British Bake Off. She says being in a relationship can make couples feel comfortable, with contentment leading to weight gain.

"You'll have a nice dinner and collapse in front of the TV. It becomes a recovery from the day so perhaps there is a tendency to go to comfort food," she says.

"Often when following strict diets when single, it's out of anxiety, trying to find someone. There's an aspect of relaxing in a relationship."

This is a view shared by Jack: "You don't think 'oh I better go to the gym', you're thinking 'I've got my girl, I love her, let's get a pizza'."

Dr Stephanie Schoeppe, from Central Queensland University, looked into the eating habits and levels of physical activity in 15,000 Australians who were in a relationship.

The study found couples had more health-promoting behaviours - they would eat more fruit and vegetables, drink less alcohol and smoke less - but "were less likely to have a normal weight, a BMI of less than 25".

"It could be because of what else they are eating daily, which might be higher in fat and sugar," she explains.

The impact of social media and dating apps

The pair met on Love Island and stayed together throughout their stay in the villa, winning £50,000 in the final

Those active on the dating scene can relate to thumb ache from hours swiping a dating app or choosing that perfect Instagram filter.

Kimberley says this can lead to anxiety about the way we look when we're single.

"There seems to be greater pressure on women to take care of their appearance in a way that will keep them competitive in the dating market," she said.

"But men are also exposed to these ideals."

Leo Reading, 30, and Simone Senior, 25, from south-west London, have been together for five years.

For Simone, that pressure of the self-image you may crave on social media is still there in a relationship.

"I wouldn't post a picture of me and Leo on Instagram unless I thought both of us looked good," she says.

Jack has over two and half million Instagram followers but tries not to over-think his posts.

"Being on Love Island helped because I've been seen in my pants, with my top off, lounging about with my belly out, but I don't think 'oh I better not put that up because I look fat or not tanned enough'," he says.

'We talk about food all the time'

Leo Reading and Simone Senior from London often use their time together to exercise and stay fit

It's the mid-morning lull, still a couple of hours from lunch, and your thoughts are already turning to tonight's dinner.

'Got a text!' you send the standard 'what do you fancy eating tonight?' reply to your other half.

"Relationships are about shared experiences. Cooking and food shopping which you do when you're single, you're now doing with each other," says Leo.

"You share the cost of rent so you have more money for takeaways or snacks."

"When we moved in together a few years ago, we found ourselves talking about food all the time," Simone adds.

What can you do to help each other?

• Fit & Fearless Valentine's Day special podcast with Gemma Atkinson and Strictly Come Dancing's Gorka Marquez

Leo and Simone try to influence each other positively.

They became vegans over a year ago and - while the pros and cons of veganism is another debate - it has made them more conscious about what they eat, which has also prompted a more active lifestyle.

"If I was in meetings, I'd go and buy a cheese sandwich, but now I'll buy a salad or a pack of nuts. There's less temptation," says Leo.

The couple also spend their time rock climbing, at exercise classes or running in Battersea Park.

Get active with friends and family

The Love Island couple have been supported by Dani's dad, who happens to be Eastenders actor Danny Dyer

It's not just Dani who sways Jack; even when younger he says his mum would tempt him into chocolate and crisps.

Much like how couples can become healthy together, Kimberley says it's important to do the same with others in your life.

"If you want to be more healthy, invite your family or friends to be a part of that and support one another," she says.

Jack's preparing for a charity boxing fight in April, and he will carry on training after.

"I enjoy it. To be fit and healthy you don't have to be ripped, you just need to be in decent shape," he says.

"It helps me mentally. When I've trained I feel like I can tackle the day."