What Would Happen If You Ate Nothing But Potatoes?

​​​This is What Would Happen If, a close examination of mundane hypothetical situations. Each week, we look at something that you could do but probably never would, and take it to its logical endpoint. This week: What would happen if you just ate potatoes?​

In terms of day-to-day vexations, figuring out what to eat is up there. Some days you have a specific craving you cannot sate, and others you must decode a vague urge to consume anything. 

But what if you made it easy on yourself? Potatoes are cheap, pretty easy to come by and they register a solid B- in terms of taste. What if you decided to just eat that? Mark Watney is a fictional astronaut who, in The Martian, survived on Mars with nothing but potatoes. You're a real person living on Earth, so why not? Who is going to stop you?

As you might guess, your body is going to stop you. But just how long, and in what ways will your own body fail you? To answer that we spoke with Vasanti Malik, a research scientist at Harvard's TH Chan School of Public Health.

In what ways will your own body fail you?

"In the short-term you would probably be fine," Malik writes in an email. "In the long-term you would be okay in terms of calories." What potatoes don't have is protein, fats and some crucial vitamins and minerals. And your body really, really needs those four things.

The first thing you would probably notice is a protein deficiency. "Protein is critical for cell and immune function and a myriad of other processes in the body," writes Malik. You'll probably start to feel constantly hungry. As time drags on your hair will thin and your nails will start to turn brittle. Your body uses protein to rebuild the immune system, so expect to get sick more often.

Eventually, the lack of essential fatty acids will start to take its toll. "Essential fatty acids are critical for hormone production and membrane function," writes Malik. This means you'll start to feel fatigued and moody due to the hormone imbalance, and you'll start to develop itchy rashes on your skin. 

It doesn't stop there though. "Not having enough fat in the diet will also prohibit absorption of fat soluble vitamins such as A, D, E and K," writes Malik. So go ahead and add on poor night vision, risk of blindness, aching, weak bones, chronic fatigue, weakness, excessive bruising and profuse bleeding to that list of Things Going Wrong.

With all the stuff that's not in potatoes out of the way, let's turn our attention to what's actually in the spud. "Potatoes are similar to refined grains in terms of in terms of glycemic (blood glucose raising) effects," writes Malik. "And our studies have shown positive associations between consumption of potatoes and risk of diabetes and greater weight gain."

It's not all bad news though. "Potatoes (especially consumed with the skin) do contain a number of vitamins including some of the B vitamins," Malik explains. She also hypothesizes that you eating the same thing over and over again might be healthy, sort of. "I wonder if boredom with the food would result in eating less, which could mitigate the greater risk of weight gain and diabetes linked to potatoes," she writes.

Those who have seen or read The Martian are most likely screaming at your computers right now: "Mark Watney just took vitamins and supplements and was only using the potatoes for a source of calories!" And you would be right. But since The Martian is a work of fiction, and this is real life, we had to ask Malik. 

"If the vitamin also contained protein (all essential amino acids) and fat including essential fatty acids, minerals such as zinc and iron, and while we're at it some more fiber (potatoes contain some fiber but not enough) then maybe this would be possible," writes Malik. "But very boring."

Further Reading

Bon Appétit's 58 Favorite Potato Recipes

The Royal Horticultural Society's Guide To Growing Potatoes

Rachel Ray On Dealing With Toxic Sprouted Potatoes

Next Week

What would happen if you actually got lost in the woods?

Got a burning (hopefully not in an infected way) hypothetical question? Submit it to [email protected]. And for more, check out our What Would Happen If archive.