An estimated 45 million Americans go on diets each year to improve their eating habits or lose weight. And while there's no shortage of diets to choose from, the latest weight-loss trend gaining an increasing number of followers is the ketogenics diet.
Halle Berry, Katie Couric and Al Roker are among the growing list of celebrities who stand behind the "keto" diet. They have attributed their weight-loss success to its low-carb formula. After losing 50 pounds following the keto plan, Vinny Guadagnino from MTV's "Jersey Shore" became one of the diet's biggest advocates. The reality star even launched a second Instagram account, @KetoGuido, which boasts over 700,000 followers, to document his new meaty lifestyle.
But what exactly is keto? Its popularity aside, is the keto diet healthy and sustainable? Here are some answers to your top questions about keto:
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What is the Keto Diet?
The keto diet is a low- to no-carbohydrate diet that helps the body to burn fat by forcing it into a state of ketosis, a metobolic process where the body uses fat instead of carbs as its fuel source. Keto is intended to be a short-term diet, according to Ruth Frechman, a registered dietitian nutritionist, targeting rapid weight loss while reportedly curbing food cravings and boosting mood, mental focus and energy.
The diet was originally introduced in the 1920s as therapy for children suffering from epilepsy after several studies indicated that the ketone chemical produced during the breakdown of fat for fuel could help to reduce their seizures.
It was developed for weight loss decades later by Dr. Gianfranco Cappello, a professor of surgery at the University La Sapienza in Rome. Cappello tested the diet in a study that spanned between 2006 and 2011, and found that it helped more than 19,000 participants lose an average of 22 pounds in 25 days.
"The treatment is safe, fast, inexpensive and has good one-year results for weight maintenance," he wrote in the study’s findings published in 2012.
What Foods Can You Eat on the Keto Diet?
Keto is similar to other low-carb, high-fat diets like Atkins and South Beach. The standard keto meal plan calls for consuming 75% of daily calories from fat, 20% from protein and 5% from carbohydrates.
According to Franziska Spritzler, a registered dietician and certified diabetes educator, these are some of the foods you can eat on the keto diet:
- Fats and high fat oils like butter, olive oil and mayonnaise
- Low carb vegetables like avocado, spinach and broccoli
- High fat dairy like cheese, heavy cream and sour cream
- Berries (sparingly)
- Artificial sweeteners like Stevia and sucralose (sparingly)
What Foods Can't You Eat on the Keto Diet?
- Grains and starches
- Breaded or cured meats
- Root vegetables like potatoes, carrots and beets
- Sweets like candy and chocolate
- Some oils: canola, sesame, sunflower
- Sweetened drinks
- Low-fat dairy items, which often have added sugar
- Sweetened sauces and dips like ketchup, barbecue sauce, some salad dressings
Can You Drink Alcohol on the Keto Diet?
While the keto diet does not ban alcohol specifically, alcoholic beverages that contain carbohydrates and more calories, such as beer, cocktails and mixed drinks, should be avoided. However, hard liquors, dry wine and champagne all fall within the guidelines of keto if consumed in moderation. Women shouldn't drink more than one drink per day, while men should stick to no more than two.
Is the Keto Diet Safe?
Some doctors and nutritionists say following a keto diet is considered safe for people who are healthy and eat heart-healthy fats. Studies have shown that it is able to accelerate weight loss in some dieters, reduce seizures in children with epilepsy and improve blood sugar control for patients with Type 2 diabetes. Many who follow a keto plan also noted an improvement on their mental focus.
But restricting one's carbohydrate intake doesn't come without side effects. For some dieters, this restriction can cause "keto flu." Common symptons of the keto flu include fatigue, dehydration, brain fog, dizziness and insomnia.
Ruth Frechman, a registered dietitian and author of "The Food Is My Friend Diet," told NBC that ketosis is not a "pleasant experience." The rapid weight loss it causes from the burning of fat calories is a result of water loss from muscles. From there, according to Mary Jane Detroyer, a New York-based nutritionist and certified dietitian, the body goes into survival mode, which means that it holds onto fat while losing muscle. When the diet is over and the person goes back to eating normally, their body begins rebuilding muscle, thereby making it much easier gain back the lost weight, Detroyer added.
"In my opinion, Keto is another fad diet setting a person up for failure,” said Frechman. “Who can sustain a diet of 80% fat that was originally meant for child epilepsy? I have had clients on keto, and their cholesterol levels have gone up."
According to Dr. Lisa Young, private practice nutritionist and adjunct professor of nutrition at New York University, most scientists reject the keto diet because it is both too limiting and deprives people of healthy foods.
“It is a poor choice — it eliminates entire food groups along with healthy food choices and nutrients in those groups,” Dr. Young, who has also written "Finally Full, Finally Slim" and "The Portion Teller Plan," told NBC. “[There is] no need to cut all carbs — fruits and whole grains are super healthy.”
To reduce your risk of heart disease and cancer, experts say it is better to eat a balanced diet that also includes fruits, vegetables and whole grains.
"No diets are a good choice," Detroyer told NBC. "We don't need fad diets, we need to be connected to our body and what it tell us. No one can tell you how much to eat, even a dietitian. Only your body can tell you this."
Should You Take MCTs on the Keto Diet?
If you're a follower of the ketogenic diet, than you may have heard the words "MCT oil." MCT, or medium-chain triglyceride, is a type of fatty acid derived primarliy from coconut oil. It is very popular among keto dieters due to its crave-curbing abilities. MCTs pass from the stomach to the liver much faster than other types of fatty acids and are quickly converted into energy, thereby decreasing the likelihood that the body will store it as fat cells while giving the user an instant power boost.
Another commonly used supplement is exogenous ketones, a synthetic type of ketone called beta hydroxybtyrate (BHB), which is created naturally by the body.
According to Michelle Milgrim, a nutritionist at Northwell Health in New Hyde Park, N.Y., these supplements reportedly help propel the body into a state of ketosis and stay there when you eat something that's not keto-friendly. But, Milgrim notes, there is little research on the long-term effects to support these claims.
"Only short-duration studies examining small samples have found that exogenous ketones can help achieve ketosis quicker and may decrease appetite," she told Women's Health magazine.
Jaclyn London, Good Housekeeping nutrition director and author of “Dressing on the Side,” reported that keto diet pills could be harmful to your health. According to London, supplements that contain MCT oil can mess with your digestion and many users experience nausea, vomiting, constipation and diarrhea. These supplements can also negatively impact your metabolism. While they initially help to decrease appetite, they have a reverse effect in the long term and ultimately can increase hunger cravings once the dieter stops taking the pills.
"I do not recommend [these supplements],” Young said. “They may give people external hope but as soon as you stop them, you can regain lost weight. I prefer lifestyle changes that people can sustain — choosing healthy foods, portion control, and exercise."