Potato Diet: What Happens to Your Body If You Only Eat Spuds?

After filmmaker Kevin Smith suffered a “massive heart attack” in February, doctors ordered him to lose 50 pounds in order to transform his health. Since then he has dropped 17 pounds—by only eating potatoes. But experts warn that subsisting solely on spuds is far from advisable.  

Eschewing other on-trend diets like veganism and keto, Smith opted for illusionist Penn Jillette’s regime. As documented in his 2016 New York Times bestseller Presto!: How I Made Over 100 Pounds Disappear, the regime sees followers eat potatoes for two weeks before phasing in vegetable stews to top up the body’s nutrients.

"It’s a pretty intense program, but it’s been interesting," Smith said of the diet on his Hollywood Babble-On podcast. "And of course necessary for my health and stuff. But once I get to a decent place, then I can think about eating again."

Perhaps surprisingly, Jillette and Smith aren’t the only ones to survive on potatoes. In 2016, former Australian marathon kayaker Andrew Flinders Taylor made international headlines by eating only potatoes for the year, losing 50kg as a result. Taylor consulted medical professionals and studied scientific papers in order to make sure the regime was safe.

“I’m getting over 600 percent of my daily iron retirements and over 400 per cent of vitamin c as well as heaps of fiber—all things that so-called experts have said I’d be low in today,” Taylor told The Independent at the time.

“The only thing of concern was calcium, potatoes have calcium but maybe not enough. To be sure I’m using a calcium fortified organic soy milk to make mashed potatoes.”

But dietitians are far from convinced that living off potatoes is a wise lifestyle choice. 

“Just eating potatoes is not a balanced intake of nutrition for the body and followed long term would leave you at risk of nutritional deficiencies,” Priya Tew, a qualified dietitian and spokesperson for the British Dietetic Association (BDA), told Newsweek.

Over the course of two weeks, the diet could negatively affect a person’s digestion, mood and associations with food, said BDA dietitian Aisling Piggott.

Read more: What Is Pegan? Vegan, Paleo Combination Diet Could Increase Risk of Eating Disorders, Dietitian Warns

"Your body will have to adapt to change in type and volume of fiber," she told Newsweek. "Boredom and fatigue of the same food will likely reduce your appetite and enjoyment of food. And as our body starts to cope with only taking in one type of food, we may start to feel sluggish and grumpy."

She added: "I do love potatoes and believe they are an unsung hero of the starchy carbohydrate world. Potatoes are rich in fiber, vitamin C and micronutrients. Potatoes can be a useful contributor to a healthy balanced diet."

"However you will not meet your protein or vitamin and or mineral requirements through potato intake alone, which increases risk of vitamin and or mineral deficiency. As with anything there is certainly not a magic answer in terms of weight loss, and while potatoes have great nutritional value, they are not and will never be nutritionally complete."

“The world we live in and our relationships with food are incredibly complex and can’t be summarized or recommended in a book or a 'fasting diet'.

"Examining one's own relationship with food and establishing routines around eating are the first and most important steps before even looking at food choices,” she said.

Instead of surviving on potatoes, Tew said that eating fruit and vegetables, a balance of carbohydrates and protein over the day and being more active is the way to go. "By concentration on your health instead of your weight you are helping your body achieve its goals of being healthy," she said.

Editor's Pick