"Crash dieting is frowned upon by many health professionals."

We all know someone who'd happily tuck into a bowl of mash or a baked potato every - but could they go for a whole week eating nothing but spuds? One woman tried just that - and ended up losing almost a stone. Charmaine, a participant on last night's episode of How To Lose Weight Well on Channel 4, ate only potatoes for seven days. The diet allowed her to eat boiled, baked or mashed potatoes seasoned with herbs, spices and oil - but chips and sweet potato were banned. Charmaine was initially up for the challenge but after a few days admitted that she was getting bored.

"I’m literally sick and tired of potatoes!," she said. "I'm really bloated. I'm going to turn into a potato by the end of this."

After a week, she was weighed and it was found that she had lost 12lbs on the diet, going from 12st 4lbs to 11st 6lbs. The results may look miraculous but there is a catch - the diet could prove to be very bad for you. Crash diets, which promise significant weight loss in a short period of time, are generally disapproved of by doctors because they can be seriously harmful on the body. The show was criticised by a number of viewers for promoting extreme dieting.

So there’s a show on called #howtoloseweightwell and it’s advising a girl to eat nothing but white potatoes all day everyday for a week cause it’ll help her lose 10lbs... Because that’s sustainable!! She’ll be fat again next week. That’s not how you lose weight well @Channel4

— Louise (@louisewalley23) January 7, 2019

Wish people would stop looking for a quick fix, it’s common sense. Exercise more eat less shite! #Howtoloseweightwell

— Rick Millar (@rick2099) January 7, 2019

I really hoped @Channel4 would not do this again. #HowToLoseWeightWell bonkers diets, unrealistic goals with no long term solutions.

— Julie Crumpton ? #FBPE #Remainernow (@kaleidobrain) January 7, 2019

People come up with anything and call it a diet if it works for someone. Lessen your calorie intake and increase your exercise amount, boring way is the most effective way! #howtoloseweightwell

— Par101 (@b10_par) January 7, 2019

#howtoloseweightwell what nonsense. Ignores health, nutrition and sustainable change. Caters solely for the vain.

— Bob (@Intrgrtd) January 7, 2019

The main issue with only eating one food is that you're unlikely to get all the nutrients you need. "A diet of just potatoes will be deficient in vitamins A, E and K, the minerals calcium and selenium, essential fatty acids, protein and dietary fibre," nutritionist Fiona Hunter told the BBC. "Although they may provide enough iron for a man, they will not provide enough iron for women." Host of How To Lose Weight Well Dr Xand van Tulleken warned that diets like the potato one could be bad for your health.

"Do remember that, although popular, crash dieting is frowned upon by many health professionals for being unbalanced and losing a lot of weight quickly can be dangerous and might not offer long-lasting results."