When choosing a new diet, you’ll want to consider how effective it will be at helping you achieve your health goals, whatever they may be — and you’ll want to be sure you’re vetting its potential health risks.

Here’s one factor to consider: Some diets, such as intermittent fasting and the ketogenic diet, are more likely than others to cause dehydration. Given that we need water to survive, health experts suggest making that part of the equation when you weigh the pros and cons of any diet.

Water helps all cells, tissues, and organs survive, per the Mayo Clinic, so you don’t want to skimp on hydration. The U.S. National Academies of Sciences, Engineering, and Medicine recommend getting about 15 cups of fluids a day if you’re a man and 11 cups a day if you’re a woman. (That said, around 20 percent of that recommendation should come from water-rich foods, like fruit and vegetables; 13 cups of fluid for men and 9 cups a day for women are usually enough for people who eat a balanced diet.)

“Any diet that is restrictive may cause dehydration,” says Keri Gans, a New York City–based registered dietitian and author of The Small Change Diet. “Most people don’t drink enough water to begin with, so we look for other ways for them to get water” — for example, through fruit. When diets eliminate fruit or other entire food groups, the risk of dehydration rises, Gans says.