By now, you’ve probably heard the buzz about the ketogenic diet. Much like other popular weight-loss diets before it, advocates say it’s the fastest, easiest way to shed pounds.
After all, you can eat virtually unlimited fat. The only catch? You can hardly have any carbs, making the diet a serious commitment, regardless of the fact you can load up on foods you’d normally only be able to eat in small quantities on other weight-loss plans, like cheese, avocado and nut butters.
HOW DOES THE KETO DIET WORK?
One thing it’s important to clarify is that the medical “ketogenic diet” and the popular “keto diet” can be slightly different.
“The ketogenic was originally used to help control seizures in children who did not see relief through medications only,” explains Deborah Malkoff-Cohen, a registered dietitian and certified diabetes educator. This diet included 4 grams of fat for every 1 gram of carbs, a ratio that’s difficult to maintain without being monitored by a dietitian. “It had to be started inpatient in a hospital,” she says.
The modern “keto diet” is similar in idea, but slightly less strict. “The diet is comprised of a very low-carb, moderate-protein and high-fat breakdown,” Malkoff-Cohen says. That might look like 5% of calories coming from carbs, 20% coming from protein and 75% coming from fat. These target percentages vary from person to person, but ketosis — or a state when your body begins using fat as fuel rather than glucose — is the goal.
It generally takes a few days or weeks to reach a state of ketosis, and when it happens, the liver releases ketones (the byproducts of using fat for energy) into the blood. When a certain level of ketones are present in someone’s urine, it’s generally an indicator that they’re in ketosis.
But does getting into ketosis automatically equal weight-loss success? Like any diet, the answer isn’t totally straightforward. Here are the pros and cons of the keto diet, according to nutrition experts.
IT CAN BE COST-EFFECTIVE
“The keto diet is one of several lifestyle change techniques that an obesity medicine specialist is trained to use, in addition to medications and VLCDs (very low-calorie diet programs),” explains Dr. Eric C. Westman, an obesity medicine physician and director of the Duke Lifestyle Medicine Clinic. “One of the advantages of the keto diet is that there is no need to purchase medications or other products — it just changes the food that people eat.” That means with some careful planning, anyone can give the keto diet a try, regardless of their financial situation.
YOU SEE RESULTS QUICKLY
One thing people like about the keto diet is that weight loss happens almost immediately in the beginning. Much of the initial weight loss is water weight, though, according to Malkoff-Cohen. Still, it’s encouraging to see some scale movement, which can help people stay committed long enough to get into ketosis.
YOU DON’T HAVE TO COUNT CALORIES
With the keto diet, you do need to watch your portions, but the proportions of macros you’re eating (fat vs. carbs vs. protein) is most important. “The keto diet is different from other lifestyle change approaches because after a day or two, the hunger and food cravings are gone, and there is no calorie counting,” Dr. Westman says. Theoretically, high amounts of fat help people on the keto diet feel full, so they don’t have to worry as much about how much they’re eating.
IT MAY WORK FOR THOSE WHO ALREADY TRIED EVERYTHING ELSE
“The ketogenic diet is one of many ways to lose weight,” notes Amy M. Goss, PhD, RD, assistant professor in the Department of Nutrition Sciences at University of Alabama at Birmingham. But for people who have already tried many other approaches to weight loss, keto might be just what they need.
“Most clinical trials examining the effects of the ketogenic diet on change in body weight have been conducted in adults with obesity and have shown the ketogenic diet to be just as effective for weight loss, if not more so, compared to low-fat approaches,” Goss explains.
“For many people, other types of weight-loss diets that focus on calorie restriction have failed them.” That could be partially because as you lose weight, your metabolism slows, but hunger remains constant. “There is some evidence to suggest that the use of the ketogenic diet for weight loss may allow an individual to side step these adaptations, ultimately increasing the chances of maintaining weight loss long-term,” Goss says.
IT’S PROMISING FOR THOSE WITH TYPE 2 DIABETES
At least in a research setting. “Evidence from multiple randomized clinical trials suggest that the ketogenic diet may be particularly beneficial in adults with Type 2 diabetes,” Goss says. “Type 2 diabetes is essentially a condition of carbohydrate intolerance. By eliminating high glycemic and starchy carbohydrates from the diet, many patients with Type 2 diabetes are able to eliminate the use of most medications while lowering blood glucose and HbA1c levels.” In other words, the keto diet has been shown to help control blood sugar in people with Type 2 diabetes.
“I do not recommend the keto diet,” says Sarah Marjoram, a registered dietitian. “From my standpoint, a diet that is this restrictive is extremely difficult to follow long term. Diets this extreme are not sustainable and often result in what I call a backlash. Once people go ‘off’ of the diet, they often over-consume the very thing that they were restricting. It’s human nature.”
IF YOU SWITCH BACK TO YOUR OLD WAYS, YOU WILL GAIN WEIGHT BACK
Similarly, Malkoff-Cohen points out that people often fail to realize that keto isn’t a “diet.” It’s a lifestyle. “Weight loss with keto depends on staying in ketosis,” she says. You cannot [go] off and on without gaining back lost weight.” Basically, the diet is no longer effective if you frequently go off-plan (Read: Cheat meals aren’t a ‘thing’) and, like many other restrictive diets, if you go back to your old style of eating (one that includes more carbs), you’re highly likely to regain the weight you lost.
IF YOU TAKE CERTAIN MEDICATIONS, SEEK SUPERVISION
Especially if those medications are for diabetes. “It is critical that patients with diabetes consult with their endocrinologist or physician before starting a ketogenic diet — especially if they are on medications such as insulin or sulfonylureas,” Goss says. “Medication needs to be reduced almost immediately when beginning this diet. If the medication dosage is not reduced, they could induce hypoglycemia in some patients.”
For the general public, supervision isn’t necessary, but it may be helpful in order to see the desired results, something that’s not required with other diets. “It may benefit most to consult with an experienced practitioner, whether it is an obesity medicine physician or a registered dietitian, to help them come up with a well-formulated ketogenic diet,” Goss says.
THERE’S NOT MUCH LONG TERM INFO ON THE DIET
We now know that fat isn’t the completely unhealthy substance we once thought it was, but we also don’t know the long-term implications of eating an extremely high-fat diet, Malkoff-Cohen points out. While fat certainly has a well-established place in every healthy diet, we don’t totally know what a diet that’s mostly fat will do to someone’s body over decades.
In the end, whether or not the keto diet is a good fit for you depends on individual factors. If you think you can stick to it long-term, then it could be worth a try. “It is important to find an eating pattern that works with your lifestyle because, with any dietary change, adherence is one of the most important factors for long-term success,” Goss says.
And if you do decide to give it a go, focus on whole foods over processed ones. “There are a number of highly processed products on the market that may appear to fit with this type of diet approach, but are actually full of unnatural and potentially harmful additives,” Goss says. “I would warn consumers to avoid such products and focus on whole food consumption when embarking on a ketogenic diet.”
Lastly, you don’t have to go full keto to watch your carb intake. “Generally speaking, carbohydrates are the foods that most Americans tend to over-consume,” Marjoram says. “As a result, I often recommend that people reduce their intake of carbohydrates as a starting point for weight loss because their calorie intake from carbohydrates is too high. This has nothing to do ketosis or an attempt to achieve it.”
To implement this approach, simply follow the ‘healthy eating plate model,’ Marjoram suggests: “Fill half of your plate with fruits and vegetables, a quarter with lean protein and a quarter with carbohydrates. This is the first step in achieving a better balanced diet that promotes weight loss and improves health.”