We spoke with Dr. Andrew M. Freeman, M.D., F.A.C.C., F.A.C.P., co-chair of the American College of Cardiology Nutrition and Lifestyle Work Group, to understand why many cardiologists are against the keto diet.

It seems like every time you check social media, someone is attributing their rapid weight loss to the keto diet and, at the same time, a health expert is begging people to stop trying the high-fat, low-carb eating plan. Here at EatingWell, we aren't fans of restrictive diets by any means—especially those that eliminate entire food groups.

We've previously sought out the expert opinions of a registered dietitian and a gut health expert on their feelings about the keto diet (spoiler: they both advise to stay far away). But what about a heart health expert? We reached out to the American College of Cardiology and spoke with Dr. Andrew M. Freeman, M.D., F.A.C.C., F.A.C.P., co-chair of the ACC's Nutrition and Lifestyle Work Group about his thoughts on keto.

"While there are still lots of unknowns, the current literature on keto is a signal of harm to one's health," says Freeman. "For some it can help with weight loss, but mostly because one is limiting what I call 'white carb-age,' or processed, refined carbs."

Freeman says people initially lose weight on keto because they are cutting out a lot of the refined carbohydrate-rich junk food they were eating beforehand. Glycogen is responsible for holding on to water in the body, so cutting out carbs rapidly can result in water weight loss, which happens quickly but doesn't last. Even though the keto diet typically leads to some sort of weight loss, he says there are much safer ways to do so.

"There is research showing that these really low-carb diets increase our risk of cardiovascular events, that's nothing new. But on top of this, the American-style keto diet is filled with lots of processed meats and cheeses, which reduce your intake of carbs but increase your intake of saturated fat, cholesterol and salt. I've seen patients' cholesterol levels at 200-300 from going on the keto diet." (Note: Cardiologists typically determine a "healthy" total cholesterol level to be at 170 or lower.)

Well, what about if you just go keto for short-term weight loss?

"If you are experiencing morbid obesity, sure, you could try it, but I prefer to offer sustainable lifestyle choices rather than a diet the vast majority of people can't maintain for long," Freeman says. "The weight usually comes back in these cases, anyways."

Freeman is certainly right about that. Nearly anyone who engages in restrictive dieting gains the weight back—and often more—within five years. Yo-yo dieting also puts one at a higher risk for several chronic diseases.

Some of the short-term consequences of keto are just as bad as making it a lifestyle. For one, Freeman says ditching complex carbohydrates means you're also missing out on all the health benefits that come with them. Fiber is only found naturally in complex carbohydrate sources, like whole grains, beans, fruits and vegetables, so you'll likely be missing out on those good-for-your-gut nutrients (hence why our gut health expert is not a fan).

Additionally, Freeman says keto is far from the anti-inflammatory diet many of us are seeking. Not only are complex carbohydrates great sources of inflammation-fighting foods, but Freeman says many of the saturated fat- and salt-laden foods prioritized on the keto diet could actually increase inflammation in the body.

"When people try the keto diet, I fear they are prioritizing short-term gains over long-term health."


A Consequence to Keto Many of Us Don't Talk About

Freeman also mentioned one compelling reason to avoid the keto diet—he says these meat- and dairy-rich diets are not only unsustainable for our hearts, but also for the planet.

"In 2019, The Lancet and Nature issued their EAT commentaries that explained our environment is likely going to continue to change for the worse by 2050 if we keep eating these animal-rich diets. Beef is one of the biggest contributors to this. If we all did keto for weight loss, we may all be skinny, but we're going to die anyway."

Freeman encourages his patients to find improved heart health and a healthy weight on a much more sustainable diet—opting for more plant-based meals from whole, fiber-rich foods. He says we can all get behind a more "flexitarian" way of eating that kicks restriction to the curb and focuses on eating for a healthier heart and planet.