What Nutrition Experts Really Think About the Keto Diet

See why elements of the trendy diet are potential causes for concern.

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The Keto Issue

It seems like everyone is hopping on the keto bandwagon, but not all nutritionists are on board. We spoke to 10 nutrition experts from around the country to find out their thoughts on this high fat, moderate protein and very low carb diet.

It Eliminates Most Fruit

"I'm not a fan of the Keto diet because it eliminates most fruits, which are powerhouses of many nutrients, vitamins and minerals," says Jonathan Valdez, owner of Genki Nutrition and media spokesperson for New York State Academy of Nutrition and Dietetics. "Nutrients mostly found in fruits include magnesium, potassium, folic acid, and vitamins A, E and C. Studies have found that adequate fruit consumption is associated with lower risks of cardiovascular diseases, cancer, obesity, osteoporosis, high blood pressure, depression, respiratory diseases and gastrointestinal diseases. While on the keto diet, you're at greater risk of heart disease and stroke. Who wants that?"

It's Too Rigid

"In order to transfer into and remain in a state of true ketosis, people have to count grams of carbohydrates, eliminate major food groups, be watchful over protein intake and even limit food choices within allowed food groups," says Malina Malkani, MS, RDN, CDN, media spokesperson for the Academy of Nutrition and Dietetics and creator of the Wholitarian Lifestyle. "For many, this rigidity can be very hard to maintain in the long term, especially in the context of social lives. While we have solid evidence establishing the effectiveness of the keto diet for weight loss in the short-term, the long-term efficacy and health implications are not yet known. Without a long-term solution in place, the likelihood of returning to pre-keto eating habits and regaining lost weight is high."

It Recommends Full-Fat Dairy Only

"I recommend all dairy foods, regardless of the fat content," says Keith Ayoob, EdD, RDN, associate professor emeritus of pediatrics at Albert Einstein College of Medicine. "Whether it's milk, cheese or yogurt, the protein, vitamins and minerals are the same, making these foods incredibly nutrient-rich. I know of no advantage of full-fat dairy over low-fat or fat-free dairy foods. There is no reason to give up any of them." Ayoob explains that milk and dairy foods have been found to be inversely linked to obesity. While low-fat and full-fat are fine, the higher-fat dairy foods will have more calories, so some balancing elsewhere in the diet will is necessary to prevent weight gain.

It Promotes Unhealthy Fats

"It concerns me that fats such as palm oil, coconut oil, lard, butter and cocoa butter are encouraged in high amounts," says Carolyn O'Neil MS RDN LD "Lady of the Refrigerator" on Alton Brown's Good Eats Reloaded on Cooking Channel. "These foods are made of unhealthy saturated fats, which are associated with increasing the body's LDL 'bad' cholesterol, one of the risk factors for heart disease."

It's a Low Fiber Diet

Elizabeth Ward, MS, RD of Better Is the New Perfect is concerned about the long term effects of a low-fiber intake, which is what results when you're on a keto diet. "Studies show that a diet higher in fiber is linked to a reduced risk of chronic conditions, including heart disease, type 2 diabetes, and diverticulitis," explains Ward. "In addition, eating a variety of fibers from fruits, vegetables and whole grains is linked to a more diverse gut microbiota, which is associated with supporting health."

You May Experience Keto Flu

Switching to a very low-carbohydrate diet can be a major change for your body and require some time to adapt. Kristen Smith, MS, RDN, spokesperson for the Academy of Nutrition and Dietetics explains that "within a few days of initiating the keto diet some people may experience a set of symptoms, referred to as the 'keto flu,' which may include nausea, constipation, headache, stomach pain or weakness. The side effects experienced during the initiation of the diet can cause many dieters to give up and return to their old eating habits. Adequate hydration and limiting your physical activity are important lifestyle factors to consider when initially starting the keto diet." Not everyone will experience these set of symptoms when initiating the keto diet, but they are something someone starting the diet should be aware of.

It's Wrongly Targeting Athletes

Keto diets are often marketed toward athletes and active people, promising to improve their performance or body composition. "You'll see convincing testimonials and carbs being demonized. However, athletes need carbohydrates to perform well," says Marisa Michael, MSc, RDN, CSSD, owner of Real Nutrition, LLC. "In studies where keto or low-carb diets were explored, athletes did not have better performance. They either had worse performance, or the same performance, but their rate of perceived exertion was higher than when eating carbohydrates. This means they could do the same exercise, but they felt a lot worse while doing it. In addition, athletes couldn't hit high intensities on a keto or low-carb diet." Your body uses carbohydrates for high intensities, such as a burst of speed, a jump or any quick, intense movement. Going keto hampers that ability to go hard when it counts.

It Advocates Lots of Coconut Oil

While coconut oil does contain some stearic acid, which is a saturated fat that doesn't impact bad cholesterol, unfortunately, 60 percent of its saturated fatty acid content is the type that will wreak havoc with your blood cholesterol levels, says Dr. Joan Salge Blake, EdD, RDN, nutrition professor at Boston University and the host of the health and wellness podcast, SpotOn!. But Blake says there is some good news: "Coconut oil is a wonderful moisturizer for your skin and conditioner for your hair. In other words, coconut oil is healthier for you on the outside of your body rather then on the inside."

You May Develop Unhealthy Relationship with Food

"As a mom, I want to consistently model a healthy relationship with food and healthful lifestyle habits," says Jennifer Hunt, RDN, LD at Healthy Inspiration. "While keto may be medically necessary for a few kids or individuals, I am concerned what messages it sends to kids when they watch a mom or dad follow this eating pattern for weight loss purposes. Due to the very limited intake of fruits and vegetables, which contain important vitamins, minerals, antioxidants and fiber, I don't see keto as a healthful family eating plan."

It's Not Sustainable Long-Term

"Rigid diets that ask you to restrict food groups, like keto, place people in a mindset of 'all or nothing,'" says Zoe Griffiths, RD, global director of Nutrition at WW (the new Weight Watchers). "Research shows that people are most successful when they have structure, but also flexibility and livability, rather than rigidity." Griffiths recommend a livability test — ask yourself if this is something that you can live with for the long term. For example, can you eat your favorite foods and enjoy social settings with family and friends? "A healthy eating approach that encourages a balanced diet and one with a flexible structure is livable and leads to establishing healthy habits," Griffiths explains.

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