Ask the Expert: Are Ketogenic Diets Healthy?

Registered dietitian Matt Priven discusses whether you should be eating keto.

Welcome to our Ask the Expert series, in which our panel of health experts answers your wellness questions. Here, registered dietitian Matt Priven debunks the ketogenic diet. Got a question of your own? Email

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Are ketogenic diets healthy? Should I be following one?


Let’s start with the basics: Keto is “a very low carbohydrate diet. You’re getting the majority of your calories from dietary fat,” Priven explains. “In practice, this means you’re eating lots of meat, fish, eggs, avocado, coconut oil, and butter,” while grains, fruits, starchy vegetables, and natural and added sugars are off limits.

Interestingly enough, keto actually began as a tool for minimizing seizures in patients with epilepsy, an area in which it appears to be highly successful. But over time, it’s transcended the medical realm and gotten dieters hooked on its promises of weight loss, mental clarity, and athletic performance, which proponents say result from operating in a state called ketosis.

In ketosis, the body draws energy from ketones, which are generated from fat when the body doesn’t have enough carbohydrates to operate. “If carbohydrates are power coming in from an electrical grid, then ketones are the emergency generator in the backyard,” Priven explains. “Both provide energy, but in different ways.”

Whether it’s a good idea to rely on the backup generator, however, is the question. Priven admits there’s not conclusive research about the long-term health effects of a ketogenic diet, but says followers need to be aware of short-term risks such as nutrient and fiber deficiency. Plus, Priven says following any restrictive diet can be triggering and lead to disordered eating in some individuals.

Finally, there’s no guarantee that keto will help you drop pounds. “Weight loss is the result of caloric deficit: If you take in less calories than you’re expending, that’s where weight loss comes from,” Priven says. “If you switch your intake to primarily one type of macronutrient—in this case, fat—it doesn’t mean you necessarily will lose weight. Those who have success with the ketogenic diet for weight loss do so only because they manage to reduce their total caloric intake as well.”

Granted, there is some logic to the idea that eating lots of highly satiating fats will decrease hunger, lowering caloric intake overall. Nonetheless, Priven says a balanced approach is a better long-term solution, whether you’re looking to lose weight or simply eat better in general.

“It’s not a magic weight loss solution,” he says. “It’s just so extreme. It’s super unsustainable.”

Matt Priven

About the Expert: Matt Priven is a registered dietitian nutritionist and the founder of Oceanside Nutrition. As an RDN, Matt is an expert in the areas of food and nutrition. He holds a M.S. in nutrition and health promotion. Passionate about research, he is a published author in multiple scientific journals, including the Journal of the Academy of Nutrition and Dietetics. Having trained and worked at Brigham and Women’s Hospital, Matt helped thousands of individuals before opening a private practice. At Oceanside Nutrition, Matt provides individual nutrition counseling in Boston and Newburyport for a variety of health concerns.

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