Is a potato-only diet good for you?

Chris Voigt at the State Potato Commission Chris Voigt and his spuds

A man in the US has eaten nothing but 20 potatoes a day for the past two months. So, the Magazine asks, what does such a diet do to the body?

Chris Voigt's reason for eating potatoes, potatoes and nothing but potatoes is as plain and simple as his diet has been for the past two months.

As executive director of the Washington State Potato Commission, he's trying to debunk perceptions that potatoes are unhealthy and instead are a good source of fibre, potassium and vitamin C.

To that end, he's eaten nothing but 20 potatoes a day - no cheese toppings, no butter and milk for mashing - since 1 October. He's had them baked, chipped, boiled, steamed, mashed, fried - and for Thanksgiving last Thursday, he feasted on mashed potato formed into a turkey shape, and pumpkin pie made with - you guessed it - mashed potato with pumpkin pie flavouring added.

Nutritionist Fiona Hunter agrees that potatoes have a bad rep. "Although many people think potatoes are nothing more than starch carbs, they are a surprising source of several vitamins and minerals. However, eating just potatoes will not provide all the nutrients needed for good health."

The Answer

Roast potatoes
  • Potatoes are a good source of potassium, vitamin C and fibre
  • But lack protein, calcium, essential fatty acids, and vitamins A, E and K
  • Risk of constipation and iron deficiency
  • If in good health at start of potato-only diet, will do him no lasting damage
  • But doing it for more than two months would start to take its toll

Critics had warned Mr Voigt it would lead to weight gain, loss of energy and worryingly high blood sugar levels from all the carbohydrates.

But in the course of his two-month diet, Mr Voigt himself says he has lost 18 pounds. His previously borderline-high cholesterol has dropped - down 52 points at the half-way mark. And the family food bill is down as he can feed himself for $15 (£9.40) a week.

"Physically I feel great. Lots of energy, sleep good at night, no strange side-effects," says Mr Voigt from his office in Moses Lake, Washington state. "I'm not encouraging anyone to go on this crazy diet, nor would my doctor. This diet was just a bold statement to remind people that there is a lot of nutrition in a potato.

"My doctor is interested to see the final results, and he suspected I would be just fine at the end of 60 days."

While nutritionist Sue Todd wouldn't recommend such a diet, she says it has more going for it than some - especially if he was in reasonably good health to start with, and doesn't continue beyond 60 days.

"Sailors on long sea voyages used to get scurvy, because they ate mainly starches from grain, which contained no vitamin C. Potatoes are a decent source of vitamin C, although they are not high in it.

"Depending on how you restrict your diet, missing out on some vitamins affects you more than others. Variety is really important to get the nutrients our bodies need."

Chris Voigt's daily diet Typical day - garlic mash, black pepper mash, rosemary mash, fried potatoes and boiled spuds

It is an eating regime that's low in fat, which she approves of, and by eating a good proportion of his potatoes with the skin on, the fibre Mr Voigt consumes cuts the risk of one-side effect associated with restricted diets - constipation.

But a potato-only diet provides none of the calcium and omega three - an essential fatty acid crucial for brain and heart function - needed for good health, says Ms Hunter.

"The body needs 40 nutrients to function and no single food will provide all of these, which is why the nutrition guidelines from groups like the Department of Health stress that we need to eat a variety of food.

"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. Although they may provide enough iron for a man, they will not provide enough iron for women.


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"One way of addressing the vitamin shortfall would be to substitute white potatoes with sweet potatoes, which have more vitamin E and A."

Mr Voigt did not take any multivitamins - something she says would help anyone undergoing this kind of regime.

And when his diet ends, what will that do to his body? Ms Todd warns of possible digestive discomfort as his system readjusts.

"He should ease himself out of it and not eat too much meat too soon, as it takes longer to digest."

So what is Mr Voigt planning to eat once freed from his self-imposed diet?

"I think my first meal is going to be a spicy beef taco, a glass of milk, a crunchy apple, and yes… roasted potatoes."

Below is a selection of your comments

We have an old saying here that roughly translates as 'eat the potato, give the skin to the pigs. The pigs get the best part'. I gather that most of the nutrients are in the skin. I never peel potatoes, even when making roasties or chips.

Glyn, Cymru Gwynedd

I was once given a sack of potatoes as a Valentines gift by my (then) boyfriend. This was not a comment on my physique, nor was it a punishment - he merely wished to give me a cheap and nutritious store of food, as I never had any money; what money I did have went on shoes and beer. I ate mostly potatoes for the next few months. Every time I ate one, it felt like a little piece of romance. Much cheaper than chocolates or flowers - I suggest all men try this with their partners.

Debbie, Cambridge

Course it's good for you as long as you have variety. Cheese & Onion, Salt & Vinegar, Prawn Cocktail, Smoky Bacon... the possibilities are endless. Do Twiglets count or are they genuinly pieces of tree and therefore count towards your five-a-day?

Ian Buglass, via Facebook

I went to a press conference to launch a potato recipe book, laid on by the British Potatoes. Everything they offered was made from potato - from the dips to the cakes to the sweeties (even little minty sweets). A real eye opener. The cakes were moist, the sweets just right.

Jackie, Edinburgh

I once read that Methodist founding father John Wesley, who travelled great distances on horseback to preach and evangelise, lived for an entire year on a diet of raw potatoes - an extreme experiment in frugality. While he converted many to his beliefs, I don't think many embraced his dietary example.

Carl Heap, London

Many countries, historically, had diets based largely around one carbohydrate - ie maize in Central America, rice in China, potatoes in Ireland - without, as far as I know, major health problems.

Dermot Nolan, Oxford

When I was pregnant earlier this year all I could stomach for the first trimester was mashed potatoes, sometimes smothered with gravy. I honestly don't think I would've survived without potatoes! I can't say that I lost any weight purely because I was pregnant and getting bigger, but my diet was certainly a lot healthier in the first trimester than it was in the rest of my pregnancy.

Susan, Mildenhall, UK

In the 19th Century, the diet of large numbers of the Irish population consisted almost totally of potatoes with milk added; this diet meant large numbers of the labourers who built the canals and railways of England came from Ireland, and were fitter and stronger than their English equivalents.

Catherine, Derby

In the 19th Century, most Irish people had no choice but to eat potatoes (with milk added) - no other crop could feed them on the land they farmed. The average Irish peasant at that time could easily go through 7lb (3.17kg) of potatoes a day. This total dependence on potatoes meant that when potato blight struck between 1845 and 1852, the result was devastation. Over a million people died of starvation and disease, and a million more left Ireland. The Fields of Athenry is a song set about this time.

Gordon, Belfast

"One way of addressing the vitamin shortfall would be to substitute white potatoes with sweet potatoes, which have more vitamin E and A." Sweet potatoes are not, technically speaking, potatoes. They are in the Convolvulaceae family, along with the morning glories, and potatoes are in the Solanaceae family.

Susanna, US

The potato is a good staple, filling, easy to prepare and store, and can be the basis of feeding a hungry family regularly, bad press was probably gained from people loading potatoes up with cheese, butter, and all manner of fillings and claiming that the potato itself was "fattening" damage done. Potato is a good, healthy and fresh food, not processed and filled with harmful E numbers and various other additives aside from ground-based pesticides, certainly a better addition to the diet compared with what many people eat.

William, London

I have more or less been on this diet for 22 years, my whole life, with the addition of bread and tomato soup. I'm really glad someone has tested this diet and shown that it is not as bad as everyone thinks.

Tom Cassidy, Derry

At one time I ate a diet of about 90% potatoes for six weeks or so. I love spuds and this was a comfort-food diet. Convenient too, since one can buy them pre-mashed and microwaveable. Lost 30lbs during that period and felt very good indeed.

Mervyn Long, Los Angeles, US

The musician PJ Harvey supposedly ate nothing but potatoes while recording her 1993 album 'Rid of Me'. I bet a bland and nutritious diet helps provide exactly the sort of distraction-free environment you need to create great art.

Jason, Cambridge, UK

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