The ketogenic, or keto, diet has taken the world of nutrition by storm, promising potential weight loss and other health benefits. Before you consider starting this diet that drastically changes the body’s fuel source from carbs to fats, it’s crucial to know (and understand!) the facts.
It’s important to remember that individual nutritional needs vary greatly. Before making any significant changes to your diet or lifestyle, consult with a nutritionist or healthcare provider.
The diet recommends a 4:1 ratio of fat to carbs. That means about 5–10% of your total daily calories can come from carbs. However, the average person consumes almost half of their calories from carbs, according to the National Center for Health Statistics. “That’s a big change!” says Julie Stefanski, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. “You’ll have to slash your carbs considerably to less than 40–50 grams spread out over a whole day.” That means eliminating grains, sugar, most fruit and starchy vegetables.
The diet recommends protein be around 20% of your daily caloric intake, which can be an adequate amount for some, says Keri Gans, a New York City-based nutritionist, registered dietician and author of “The Small Change Diet.” It’s a good idea to check with a registered dietician to gauge your individual needs before trying keto.
“The diet is high in saturated fat, and research suggests such diets may increase one’s risk for heart disease,” Gans says. Although the fat should keep you satiated, if you eat too much, you may cancel out any potential weight-loss benefits, Stefanski adds.
“Supplementation with vitamins and minerals is an absolute necessity on this type of diet,” Stefanski says. “Pure fats like coconut oil, olive oil and butter and many other fats that make up the base of a keto diet aren’t great sources of vitamins. Your body is using these nutrients constantly, but they’re not being fully replaced.” You’re also missing out on beneficial antioxidants in fruit and root vegetables, which have been associated with a decreased risk of cancer, heart disease and other conditions.
Constipation, bad breath and dizziness are just a few of the side effects of going so low-carb. “Without carbs, dieters can easily miss out on fiber and end up with digestive issues,” Stefanski says. She recommends including chia and flax seeds, coconut, nuts and low-carbohydrate vegetables at every meal if you decide to go keto.
It’s also difficult to include prebiotic foods such as onions, garlic, bananas and oats on a very low-carb, high-fat diet. “These foods encourage good growth of bacteria that support our intestinal health, which is tied to our overall health,” Stefanski says. “But we don’t know yet how the lack of fiber on a ketogenic diet impacts our microbiome or gastrointestinal health long-term.”
“Keto does not show a performance advantage for athletes, especially in sports which rely on the fuel you already have stored in your muscles as glycogen,” Stefanski says. Non-athletes may also lack the energy to exercise at their best, Gans adds. “Carbs are the preferred type of fuel for the body, so without them your workout could suffer,” Gans says.
Not only do many ketogenic diet advocates advise eliminating alcohol, the guidelines cut out lots of foods we tend to eat when gathering with friends. “It can impact your social life, especially when so many events revolve around food,” Stefanski says.
Eating out can be a challenge on the ketogenic diet since it bars common foods such as bread, pasta, rice, ketchup and many dressings. Plus, most packaged foods aren’t keto-friendly. “You should be prepared to make the time to cook appropriate options if you want to follow the diet,” Stefanski says.
The jury is still out on whether a ketogenic diet is beneficial or harmful to cholesterol levels, so see your doctor for a fasting lipid panel before starting the diet and three months later if you plan to continue, Stefanski recommends.
The ketogenic diet is very restrictive and takes a lot of commitment to get the nutrients you need for overall health. Gans doesn’t recommend the diet for long-term, healthy weight loss. Stefanski says to seek a doctor or registered dietitian with experience in keto if you wish to try it.
