It seems like almost everyone is trying the keto diet, and there are many stories of rapid weight loss out there. But we wondered about eating all that fat – most keto diet regimens recommend you get 80 percent of your calories from fat – is that healthy for your heart?

We asked Tracy Severson, R.D., L.D., dietitian for the Center for Preventive Cardiology at OHSU’s Knight Cardiovascular Institute, and she was quick to set the record straight.

“The short answer is no,” Severson says. “Even if you choose all healthy fats, like olive oil and fish, you’ll still end up eating more saturated fat than is safe and healthy.”

Most people aren’t eating the healthiest version of the diet anyway. “So many people think it’s about eating bacon and meat, but often they are eating too much protein to be on a true ketogenic diet. It’s about fat, not protein,” says Severson.

Moreover, what you’re not eating can also increase your risk of heart disease. When you avoid whole grains, legumes, and fruit, you lose a lot of the dietary fiber that helps protect your heart.

While individual results of the diet can vary widely in different people, most people will see a rise in their cholesterol level, even if they lose weight. For people with a history of heart disease or high cholesterol, this can be especially dangerous.

Dietitians and researchers also don’t have enough data yet to know exactly how the keto diet could impact people over the long term.

But what if you’re generally healthy, with a low risk of heart disease?

“It’s probably safe to try on a short-term basis,” says Severson. “But remember that it’s very hard to maintain long-term and live a normal lifestyle.”

In fact, a study comparing the keto diet to a low-fat diet found that after a year, people who were still on the keto diet had only lost two more pounds on average than those on the low-fat diet. And the keto diet is much less likely to be maintained over time.

“What often happens is that you lose a bunch of weight quickly, then gain it back when you stop the diet,” Severson says. “The better solution is to just choose healthier foods.”

Instead of trying keto, or any other fad diet, she encourages people to make changes that are sustainable. A healthy, whole-food diet is still the best solution over time.