Approximately 40% of Americans make a New Year’s resolution to lose weight. An even higher percentage set their goals on “getting healthier” in the year ahead.
If you’re one of those Americans, you may have come across the ketogenic diet, or “keto” diet. As with any drastic diet change, you’ll want to consult your primary care physician before you begin. But the following list of nine need-to-know facts from the experts at the University of Kansas Medical Center can help you decide if a keto diet might work for you.
1. “Keto” is sometimes used as a blanket term to cover a lot of popular diets, often incorrectly.
A lot of popular diets say they are “keto” but not all are ketogenic. In the early 2000s, diets such as Atkins, South Beach and Paleo attracted people looking for quick weight loss. All have slightly different rules but focus on cutting carbohydrates.
“There are a lot of different ways to do the ketogenic diet,” explained Russell H. Swerdlow, M.D., professor of neurology, biochemistry and physiology in the KU School of Medicine and director of the University of Kansas Alzheimer’s Disease Research Center.
The original ketogenic diet derived 70-75% of all calories from fat, 20-25% of calories from protein and 5-10% from carbohydrates. “Now we use a looser definition of a ketogenic diet as any diet that raises the levels of ketone bodies in the blood,” Swerdlow said. For an explanation of how that works, see fact 2.
2. A true keto diet changes the way your body burns energy.
People get the energy to fuel their cells from the foods they eat. In a typical Western diet, a majority of that energy comes from carbohydrates, which causes the body to produce insulin. In keto diets, where carbs are extremely limited, the body instead draws its energy from dietary fat and the body’s fat storage, which produces ketone bodies.
Those ketone bodies then can be measured in the blood to see if ketosis —the act of the body burning up fat instead of carbs —has been achieved. For more on ketosis, see fact 4.
3. A keto diet helps people lose weight in part because they don’t feel as hungry as they usually do on an average diet.
When you eat a diet high in carbohydrates, your insulin levels rise after you eat, but then quickly fall. This decrease in insulin alerts the hunger center of your brain to provide more food. Your body will often “crave” something to bring those insulin levels back up, and that choice feeds into a cycle of high carbohydrates as the major source of calories in a Western diet.
“If you're on a ketogenic diet, and you're not eating carbs, then your insulin levels stay pretty level, at a steady, low level,” Swerdlow said. “So, you don't get the fluctuations in insulin. And when you're not getting the fluctuations in insulin, that can reduce your hunger.”
And because fats and proteins take the body longer to digest, you may feel fuller longer. “The food sits in the stomach; it doesn't empty out of the stomach as quickly, so you feel fuller,” he said.
4. There are no “cheat days” on a keto diet.
Debra Sullivan, Ph.D., chair of the Department of Dietetics and Nutrition in KU School of Health Professions, cautioned that the diet must be followed closely so the body can achieve ketosis, or the act of the body burning fat as opposed to glucose, which our bodies derive from carbohydrates.
“As a dietitian and a nutrition scientist, we often don’t like to cut out whole food groups. And it’s not something I would recommend to the general population. But certain populations can benefit,” she said.
5. The key to burning fat is, paradoxically, increasing the amount of fat in your diet.
Sullivan suggests meeting with a dietitian to understand how much fat intake is needed and what kinds of fats should be consumed. “On keto, we are increasing the amount of fat in someone’s diet, but we need to make sure it’s a healthier type of fat.” Too much of the wrong kind of fat can negatively affect the heart and the cardiovascular system. For example, choose olive oil over corn oil and avocados over red meat.
6. Individuals following a ketogenic diet need to drink a lot of water to avoid kidney stones and other kidney problems.
Swerdlow explained that when the body stores carbohydrates, it also ends up storing water. “People who go on a ketogenic diet may rapidly lose weight, which is encouraging, but a lot of that weight loss may be water weight,” he said. “So, if you’re not storing sugar, you’re not storing water. You have to be careful to replace your water so you don’t become dehydrated.”
Dehydration can lead to kidney stones and other kidney problems, which is why your kidney health should be closely monitored while on the diet.
7. One side effect of starting a ketogenic diet could be the “keto flu.”
You may experience multiple days of headache, fatigue and constipation a few weeks into the keto diet, which can be attributed at least in part to the body losing water. (See fact 6.) But you might also experience brain fog, irritability or difficulty sleeping. All are symptoms of a condition known as “keto flu.”
Jessica Keller, dietitian and study coordinator in Sullivan’s Nutritional Assessment Laboratory at KU Medical Center, counsels clinical trial participants who are set to begin a keto diet. She said many of the symptoms can be alleviated with water, rest and time. She herself has maintained a keto diet for more than five years and considers the long-term effects worth any short-time symptoms.
“I sleep better, I have more energy and my skin is clearer,” Keller said. “I just feel better when I’m not eating a lot of carbohydrates.”
8. A keto diet will cost more than a typical American diet.
Be prepared to spend more money on groceries, as carbohydrates tend to be much less expensive than the staples of a keto diet such as meat, fish, avocados and high-fat dairy items. The good news is that more keto-friendly foods are becoming available in stores and restaurants.
“I tell people that one of my hidden job benefits is that I have to go out and try these new keto products all the time,” Keller said. “Keto ice cream, keto pastries – they do exist.”
9. A pilot study conducted by KU Medical Center showed that individuals with Alzheimer’s disease improved their cognitive performance on a keto diet.
Since the 1930s, experts have known that ketogenic diets affect how the brain works. Back then, scientists discovered that children with epilepsy had fewer seizures while on a ketogenic diet.
Faculty from KU School of Health Professions and KU School of Medicine (all the experts named in this article) worked together to test how a ketogenic diet might affect individuals with Alzheimer’s disease. Of the handful of clinical trial participants, those who stayed on the diet showed a 5-point improvement in their cognitive scores while on keto, but those points were lost once the participants returned to their normal eating habits.
“I think there’s a lot of work to be done in this area of research,” said Matthew Taylor, Ph.D., assistant professor of dietetics and nutrition in KU School of Health Professions. In addition to researching the affects of a keto diet on Alzheimer’s patients, Taylor is also taking a look at how the diet might affect clinical trial participants with traumatic brain injuries.
“The keto diet is so different from what most of us normally eat. The diet may not be for everyone, but it’s such a potent metabolic intervention,” he said. “It changes the way a lot of bioenergetic processes happen in our body.”
