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The pros and cons of keto cycling, according to health and medical experts

What happens to your body when you go on and off the keto diet? Experts explain.
Mixed salad with tuna
If you want to give keto cycling a try, experts recommend cycling in healthful sources of carbs instead of those craveable, heavily processed refined or sugary carbs.Westend61 / Getty Images/Westend61

Fans of the high fat, low-carb keto diet praise its appetite-crushing benefit, which is why keto dieting is so popular for weight loss. But since we don’t live in a keto-friendly world, the call of carb-rich fare — from healthy options, like fruit, yogurt and oatmeal to less healthy foods, like pizza, French fries and dessert — can make it hard to stick with the keto diet. Even if you’re not craving carbs, a normal social activity, like dinner at a friend’s house, can pose problems. Enter keto cycling. In this fairly new approach, you cycle on and off the keto diet at various intervals. Though this may sound like the best of both worlds, there are some red flags you should know about.

Keto cycling, explained

The keto diet is designed to encourage your body to adapt to using fat instead of its preferred fuel source, glucose, which is the substance that’s broken down from the carbohydrates you eat. Though it sounds simple enough, the process involves many biological modifications and it may take a few weeks for these changes to occur. You’ll lose weight during this process — initially mostly water weight — as your body depletes its remaining carbohydrate stores (known as glycogen) and makes this adaptation.

The main challenge keto dieters face is the extreme carb limit, which is capped at about 5 percent to 10 percent of your daily calorie intake, or around 20 grams of carbohydrates per day, depending on your individual calorie level. This amount of carbs is less than the amount in a large banana and given that even non-starchy foods, like nuts and broccoli, contain some carbohydrate, you’ll reach the cap easily. That means doughy foods, like pizza, pasta and bagels, as well as sweets, are strictly off limits. That’s why keto cycling is so appealing.

Though it has no official definition and there’s no actual science to back up its effectiveness, many people take it to mean following the keto diet for five or six days and then following a higher carb menu for a day or two. Besides the obvious benefit of being less rigid, adding back nutritious carbs, like fruit, beans and whole grains, can provide a spectrum of health-protecting substances, including fiber, which is often low on a typical keto menu.

How does keto cycling impact weight loss?

According to the recently released National Lipid Association’s scientific statement published in "The Journal of Clinical Lipidology", this type of eating pattern is difficult to maintain and while those who follow it often experience an initial weight loss advantage, over time, the keto diet’s weight loss benefits aren’t any better than a more balanced plan.

In theory, keto cycling might make it easier to follow this program, but according to Molly Devine, RD, owner and founder of MSD Nutrition Consulting and Eat Your Keto, the reality may be quite different. “Few people have the ability to go on and off keto successfully,” she says, explaining that the main challenge is intense cravings for carbs and sugar, which come back once you reintroduce these foods. In Devine’s experience, this is true whether you take a break for say, a holiday weekend, or even just a meal.

“For those who have struggled with sugar addiction and battled getting sugar out of their diet, following a strict ketogenic diet is the first time they don't feel overwhelmed by cravings due to the metabolic shift from glucose for fuel to ketones. Keto cycling or cheat meals are very challenging for this group because as soon as they get a taste of those foods, the cravings hit hard and they have a tough time getting back on the wagon,” she explains.

Franziska Spritzler, RD, CDE, a writer and expert on the medical review board of agrees, but says it can depend on the person. She explains that some people do well knowing they can have a small scoop of ice cream or another non-keto treat on occasion — and that planning for these non-keto foods can make it easier to stay on the keto diet and facilitate weight loss and better blood glucose control. But she admits that for other people, this approach can lead to intense carb cravings, making it difficult to return to the keto diet.

What are the risks of keto cycling?

Setting aside intense cravings, there may be other risks of cycling on and off the keto diet. In one short-term, small study, researchers investigated the impact of following a strict keto diet for six days and then going off plan by consuming a drink containing 75 grams of carbohydrate. For reference, that’s slightly less than the amount of carbs in two cans of soda. The damage: “We saw a temporary increase in the levels of endothelial microparticles (sometimes called micro vesicles) in the blood,” explains study co-author and Assistant Professor at the University of British Columbia Jonathan P. Little. Endothelial cells are the single layer of cells that line and protect our blood vessels. “Microparticles are small vesicles that get released from cells when they are inflamed or damaged, so finding an increase in endothelial microparticles tells us that the endothelial cells that line our blood vessels experienced some damage and inflammation when glucose spiked.” Though he says that the increase in markers of blood vessel damage was temporary, the long-term impact remains unclear. “We know that these endothelial microparticles are elevated in conditions such as heart disease and type 2 diabetes, which is why we were interested in measuring them,” he explains.

Besides the potential for blood vessel inflammation, Little also cautions that the metabolic adaptations your body experiences on the keto diet means that you’re relatively glucose intolerant, so a meal (or day) of high carb eating might not be the best plan. “When you adapt to a ketogenic diet, you become a proficient fat burner and this occurs at the expense of carbohydrate metabolism. It probably isn’t the best thing for your metabolism to throw carbohydrates (especially high glycemic index carbs in high amounts — such as a glucose tolerance test drink that we used or a big 'cheat meal') into the mix if you are on a ketogenic diet,” he says.

Devine agrees and shares concerns about the long-term risks of this approach. “The benefits from a ketogenic diet are a one-way street,” she says. “You can get away with a high intake of dietary fats (including saturated fats) without the negative impact on risk factors for cardiovascular disease (specifically, particle size of LDL and triglycerides) only when these foods are not consumed in conjunction with refined carbs and sugars,” explains Devine. In her view, going back and forth will cause more harm than benefit over time. “I stress the importance of not cheating on a keto diet because once you start introducing sugars, the high-fat aspect can do more harm than good long-term.”

Experts also caution about the risks to your emotional health with keto cycling. “Starting keto with the idea that you can go off plan whenever you want and just jump right back in when you feel like it may be counterproductive for your weight, overall health and quality of life, explains Spritzler. Devine also notes that chronic yo-yo dieters may become less successful over time. In her experience, each keto hiatus can become longer and longer and as a result, it’s likely you’ll put the weight back on. At that point, the hurdles start to feel insurmountable, she says.

What’s the healthiest way to try keto cycling?

Despite the concerns, if you want to give keto cycling a try, experts recommend cycling in healthful sources of carbs instead of those craveable, heavily processed refined or sugary carbs. Think sweet potatoes, beans, milk and fruit over muffins, rolls and chips.

It’s also a good idea to make a plan for your carb-heavy days so you get the most benefit. For example, Spritzler says you might eat them on a workout day. “Pay attention to how you feel on the days you eat more carbs,” she says. Some questions she suggests asking yourself: “Do your energy levels drop or soar? Are you happier and satisfied or anxious and hungry? Does your sleep improve or worsen?” Pay attention to your answers. “If you feel better off eating carbs occasionally and it doesn't seem to interfere with your weight, keto cycling may be a good fit for you. On the other hand, many people do seem to benefit from staying consistently keto or alternating keto with low carb (around 30-60 grams of net carbs per day),” she explains.

Whether you add in those higher carb days or not, your keto diet should focus on other principles of healthy eating. Devine says to emphasize whole foods, quality proteins and heart-healthy unsaturated fats, such as olive oil, avocado, nuts, seeds and fatty fish instead of processed saturated fats, like cheese and processed meats. Spritzler agrees that the focus should be on minimally processed foods and she suggests this simple framework: Consume adequate protein (3-6 ounces) at every meal, include vegetables at most if not all meals, and eat enough to feel full but not stuffed.

Is keto cycling right for you?

The prescriptive nature of total carb abstinence may be appealing to some, but for others, can feel unnecessarily rigid. It’s important to get clear on where you fall in the spectrum and use that to guide your dietary decisions. Whether you’re trying to lose weight or just get healthier, it also makes sense to think about the foods you enjoy and the way you like to cook and then pick a plan that lines up with your food and lifestyle values. Be real with yourself and identify some non-negotiable foods. If pasta is one of them, keto cycling might be preferable to keto, but you might want to try another approach altogether.

Remember that the keto diet isn’t the be all end all — even for weight loss. As Kevin C. Maki, co-author of the National Lipid Association Scientific Statement points out, the long-term health impact is unknown. “While ketosis may have some benefits for reducing appetite, it may not be necessary to go to such extreme levels of carbohydrate restriction to lose weight and experience some of the other benefits, such as improving blood glucose excursions and triglyceride levels,” says Maki, who’s also an Adjunct Professor of the Department of Applied Health Science at the School of Public Health at Indiana University, Bloomington Indiana. He acknowledges that a keto-type diet for a limited period of time may work well for some people, but also points out the issues with long-term compliance. “Our general view is that most people would be better off focusing on regular exercise (e.g., walking) and consuming a high quality diet that emphasizes fruits, vegetables, whole grains, nuts, seeds, legumes, seafood and non-tropical oils, such as a Mediterranean diet pattern.”

Dr. Suzanne Steinbaum, Director of Women’s Cardiovascular Prevention, Health and Wellness at Mount Sinai Heart, Fellow of the American College of Cardiology and American Heart Association, and spokesperson for the American Heart Association’s Go Red for Women campaign, is also in favor of the Mediterranean diet over the keto diet or keto cycling approach. She says the Mediterranean diet has been shown to reduce the incidence of heart disease by as much as 30 percent and that weight loss and better blood sugar management can be achieved by boosting your vegetable intake and cutting way down on your consumption of overly processed carbs and sweets.

No matter which approach you go for, remember that the idea is to adopt healthier eating habits — not just for the next few weeks or months, but for life, which is the real key to healthy and sustainable weight loss.


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