The ketogenic diet has gained immense popularity as a weight loss plan. It involves drastically reducing carbohydrate intake, moderating protein consumption, and increasing fat intake. After following the ketogenic diet, or keto for short, for a few days, your body will enter ketosis. A study in the May 2021 issue of Nutrients linked this state to weight loss, better glucose control, and improved cholesterol. However, some health experts do not recommend the diet because it can lead to kidney problems, increased intake of “bad” fats, nutrient deficiencies, and an obsession with food. Another significant downside of keto is the difficulty of maintaining ketosis. While on the keto diet, you’ll typically consume a maximum of 20 to 50 grams (g) of carbohydrates per day, as the Harvard T.H. Chan School of Public Health advises. As a point of reference, the U.S. Department of Agriculture notes that one medium-size pear has 27 g of carbs.
The sudden reduction in carbs can shock the body. Susan Kieffer, the department chair of the school of nursing at Purdue University Global in Helena, Montana, explains that one of the challenges many people encounter when they try the keto diet for the first time is the drastic lack of energy they experience in the first few days. This is the time when the body learns to use fat for energy rather than readily available carbs. You can feel very tired during this time and even a little fuzzy in your thinking. This experience is so common that it’s been dubbed the “keto flu.” Carb cravings are another reason the diet is tough to stick to.
To combat these challenges, some people turn to keto cycling. Keto cycling involves following the keto diet for a certain amount of time and then taking a day (or more) off. Molly Devine, RD, the founder of MDS Nutrition in Durham, North Carolina, notes that it’s also called carb cycling because there are higher-carb days and lower-carb days. The idea is to make the keto diet easier to follow. Knowing there’s a day in the near future when you’ll be allowed to eat carbs again might help you stick to the diet for longer.
What is Carb Cycling?
Carb cycling is a dietary approach that alternates between high-carb and low-carb days rather than maintaining constant carbohydrate intake. The concept was developed by competitive bodybuilders who used it to burn fat, build muscle, and train harder before an event. With carb cycling, you may even have “no carb” days.
Carb cycling involves planned increases in carbohydrate intake, allowing people on a ketogenic diet to temporarily exit ketosis and reintroduce carbs. The length of these cycles can vary, from a few days to several weeks, depending on personal goals.
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In essence, carb cycling is a dietary plan in which you alternate your carb intake daily, weekly, and monthly. Carb cycling is flexible, and you can adjust it to fit your needs. A typical carb cycling plan may look like five or six “low-carb” days and one to two “high-carb” days. Many athletes and bodybuilders align high-carb days with high-intensity workouts. This comes down to science: Your body runs off glucose during your workouts. Consuming carbs after training will also help refuel your glycogen stores.
How Does Keto Cycling Work Exactly?
Keto cycling doesn't have a strict definition. Some people choose to have five or six days on keto followed by a day or two off. Others will do keto for 10 to 12 days followed by three to four days off.
Devine typically doesn’t recommend taking more than two days off keto. She notes that several higher carb days in a row almost always lead to ‘falling off the wagon’ and the return of intense carb and sugar cravings for most people. She suggests starting with just one day so you can see how your body responds and how quickly you return to ketosis afterward.
She warns that if you have too many carbohydrates, you’re going to build up your glycogen stores, and it’s going to be very hard for you to get back into ketosis. She says to think about your glycogen stores, which are your body’s supply of stored carbohydrates, as a gas tank. As long as we don’t let that tank dip over, we can deplete it pretty quickly again and get back into ketosis. But as soon as we go beyond that three or four days [off keto], our tanks flood and you start to store some of that glucose as fat, and it becomes very difficult to deplete that tank again and get back into ketosis.
On those higher-carb days, Devine recommends sticking to whole foods with low amounts of sugar rather than going on a full-blown carb binge. Foods like fruit, sweet potatoes, and whole grains - all considered complex carbs - rather than white bread and sweets will make it easier for the body to re-adapt to ketosis. Consider what time of day you’re eating these carbs, too. It’s best to eat carbs (again, opt for those complex choices) in the daytime when you're most active (if that's true for you) as opposed nighttime, Devine says.
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Devine says not to jump right into keto cycling. She advises that you should definitely not try keto cycling until you’re about two to three months into your keto diet because you need to make sure your body is fat adapted so that it can get back into ketosis easily. In her practice, Devine has noticed that if the body is used to being in ketosis, it’ll snap back more quickly after eating a carb-heavy meal than if a person is new to keto, though there’s not enough research to confirm that this is always the case. She doesn’t encourage keto cycling unless the individual has been following a clean keto diet, which calls for sourcing the healthiest version of keto-approved foods, such as grass-fed meat and whole foods, for at least three months and has a regular and rigorous exercise plan. This should allow them to eat higher carbs without seeing weight gain or intense cravings.
Devine says to follow up a high-carb day with vigorous exercise the next morning. The idea is to force the body to burn the glycogen you took in so it can get back to working on fat burn.
Potential Health Benefits and Risks of Keto Cycling
Because keto cycling is so new, no studies have examined the benefits and risks yet. Kieffer says cycling in and out of ketosis - eating carbs then not eating carbs - might be dangerous. She explains that if you eat a high-fat diet one day (like what is recommended in the keto diet) and then go back to eating carbs the next, a person could be in danger of storing much of that consumed fat, which can result in high triglycerides and cholesterol because the body may not have time to convert fat to energy, so it may stick with using the carbs for energy and storing the fat.
There isn't much research on keto cycling, though one small study was published in September 2020 in Nutrients. The researchers found that keto cycling resulted in an amount of weight loss in young, healthy men similar to that engendered by a nutritious diet that cut 500 calories per day. The weight loss for the keto cyclers, however, was from a combination of decreased body fat, water, and lean body mass, whereas the other dieters primarily lost body fat.
Some anecdotal evidence suggests that people are more likely to stick with keto if they incorporate cycling. You could also end up losing more weight if you stick with the diet for a longer period than you otherwise would have.
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Some people believe elite athletes benefit from keto cycling because their bodies use extra carbohydrates as energy to power through difficult workouts and races. Devine notes that for an avid athlete, timing carbohydrate intake based on intensity and type of activity can have performance benefits.
After all, research has shown that the strict keto diet impairs exercise performance. One study found keto hurts athletic performance more than a high-carbohydrate diet or one that includes periods of high carbs and low carbs (which is similar to keto cycling).
It seems the body uses high-quality carbs as exercise fuel. Devine says that running on glucose (carbs) during intense strength training workouts can be beneficial. Another study, published in Nutrition Today in January 2018, found that carbohydrates are the only macronutrient that can be broken down quickly enough for the body to use during high-intensity exercise.
Challenges Associated With Keto Cycling
Because it’s best to try keto cycling after your body has already adjusted to ketosis, you likely won’t be able to avoid the challenges of starting keto, such as the keto flu.
And while Devine says keto cycling can be helpful for people who crave higher-carb items from time to time, she warns it’s not for everyone.
Devine has noticed that some people who try keto cycling do find it difficult because when you reintroduce carbohydrates back into your diet - and this is more about refined carbs, not eating an apple - you don’t feel very good. She says some people experience a so-called carb hangover - the body feels kind of bloated and inflamed, and you may develop headaches.
It can also be a challenge not to overindulge on those days off the diet. Devine warns that for somebody who’s been a carb addict or a sugar addict before going on the diet, all of those cravings for those sugars and those carbs come back pretty strong. She likens it to saying, ‘I’m going to stop smoking, but I’m going to have one cigarette a month.’ She thinks it's a hard dietary approach to follow.
Should You Try Keto Cycling?
Be careful about starting keto cycling or keto in general if you’re pregnant or nursing. Kieffer recommends that these women consult their primary care provider first. People with type 2 diabetes should also consult their doctor, and those with type 1 diabetes or kidney problems should avoid the diet, as should anyone with conditions related to their pancreas, liver, thyroid, or gallbladder, according to University of Chicago Medicine.
If you’ve cleared the approach with your healthcare team and weight loss is your ultimate goal, know that keto cycling won’t be nearly as effective as traditional keto, Devine points out. She notes that it can halt your weight loss by taking those days off because during that time you’re not going to be burning any fat and you could be putting more on, and she has seen ‘cheat days’ turn into cheat months and just backfire for the client completely because it creates a very ‘yo-yo’ approach to weight loss which can be very discouraging. Kieffer adds that the results of keto cycling are never as dramatic as when the body is kept in a constant state of ketosis.
On the other hand, if you take the approach of following the keto diet most days but cycling helps you stay on course, cycling could help you stick to the keto diet longer.
What it boils down to is this: You need to know yourself and your self-control. Devine suggests that if you’re able to have a higher-carb day that includes healthy carbs and be able to get back on track the next day, then it might work for you, but if you’re somebody who kind of loses control when you get around sweet foods, and one doughnut means the entire case of doughnuts, you’re going to have trouble with it.
Carbs: Simple vs. Complex
Carbohydrates are the body’s most preferred source of energy. There are two types of carbs: simple and complex carbs. Complex carbs are preferred because they digest more slowly, which helps prevent blood sugar spikes. Examples of simple carbs include white pasta, candy, and soda. Examples of complex carbs include brown rice, quinoa, and non-starchy vegetables.
How to Incorporate Carb Cycling
First, you need to figure out how many carbs per day you should be eating. A carb cycling plan involves a ketogenic approach with lower-carb days. This means it’s important to understand how many carbs you should consume. A good rule of thumb is 50 grams of total carbs per day. If you’re still experiencing symptoms of the keto flu after the two-week mark, your body might be asking for more carbs. For example, if you’re super active, you might need more than 50 grams of carbs per day. If you’re hitting 50 grams per day but not factoring in net carbs, you might need to raise your daily carb intake.
Carb Cycling on a Ketogenic Diet
Carb cycling can support weight management, blood sugar control, and insulin sensitivity. That said, it does not boast all the benefits of a keto diet. The lower-carb days on a carb cycling plan may still exceed the amount of carbs you need to consume to stay in nutritional ketosis. However, there is a way to carb cycle on a ketogenic diet through cyclical ketosis. This carb cycling approach allows you to pick one day per week to eat more high-quality carbs (approximately 150 grams of net carbs). On your carb refeed day, you can add things from this carb-cycling food list. Note that you may temporarily dip out of ketosis on your higher-carb day, but once your body burns through those extra carbs, you’ll return to ketosis. This is called metabolic flexibility. Carb cycling this way allows you to take advantage of all the keto benefits. These include appetite suppression, fat burning, improved energy, and focus.
When it comes to the keto diet, you aren’t limited to one style of eating. There are variations of the ketogenic diet that can help you stay in a fat-burning state while increasing your carb intake.
- Targeted keto: This plan is great for athletes because you eat more carbs before you work out. That way, your muscles have glucose available to power through your session.
- Ketone salts: Not all the ketones in ketone salts are bioidentical. This means the body may not be able to use them.
- Ketone esters: This option is more effective than ketone salts, but keto esters have a chemical-like flavor.
Keep in mind that exogenous ketones are not necessary to maintain a state of ketosis.
Tips for Carb Cycling
- Choose high-quality carbs. On high-carb days, don’t use carb cycling as an excuse to binge on foods packed with artificial ingredients. Pass on simple sugars and refined carbs and choose unprocessed carbs instead.
- Prioritize fiber. On low-carb days, eat lots of fiber to reduce hunger. Some of the best high-fiber, low-carb options include fruits like blackberries, raspberries, and avocados. Other options include legumes like lentils and chickpeas.
- Listen to your body: As you try carb cycling, listen to your body. This will help you discover what works best for you and your health goals.
The Importance of Metabolic Flexibility
Improving metabolic flexibility is the foundation for getting the most out of various diet plans, losing weight, and keeping it off long-term.
On high-carb days, eating more carbs increases insulin levels and promotes energy storage and muscle growth. As the carbs you eat are converted to glucose, the pancreas releases insulin to help move glucose from the bloodstream into your cells, where it can be used for energy. When insulin levels are high, mitochondria are more likely to use carbohydrates for energy. Moreover, insulin directly affects muscle protein synthesis, activating the mTOR pathway essential for muscle growth. This is important because muscles are packed with mitochondria. High-carb days also replenish depleted glycogen, the storage form of carbs in your muscles and liver. Topping up your glycogen is beneficial because it acts as a rapid energy reserve, especially during intense physical exertion.
On low-carb days, the focus shifts. This move to using fat trains the mitochondria to become more metabolically flexible and efficient at metabolizing fat for energy.
Keto Diet: An Overview
The ketogenic diet is a low-carb, high-fat nutrition plan that moves the body into a metabolic state called ketosis, where mitochondria rely on fat for energy. As fat oxidation increases due to low glucose availability, the liver converts fatty acids into ketone bodies to efficiently provide energy. Ketogenic diets change the body’s metabolic machinery to utilize fats as a primary fuel, which can lead to improved metabolic health. Evidence also suggests that ketosis leads to weight loss as the body taps into fat stores for energy, helps burn fat, improves insulin resistance, and even sharpens cognitive functions.
However, the keto diet is not a sustainable nutrition or weight loss solution because long-term keto keeps glycogen levels very low, pushes the body to break down muscles for energy, and causes your mitochondria to rely on fat for fuel. Depleting muscle mass reduces mitochondria and fat-burn potential, while constantly relying on fat for energy can make your mitochondria less efficient at using carbs, leading to reduced metabolic flexibility and quick weight gain when you return to eating carbs.
Choosing the Right Approach
Choosing which nutrition plan to follow ultimately comes down to what you can turn into a healthy lifestyle and sustain for the long-term. This can be helped by improving your metabolic flexibility through metabolic trackers. Instead of relying solely on a fixed meal plan for months on end, carb cycling based on immediate biofeedback is more fluid.
- Figure out which approach will be the most sustainable for you to follow. Many people might find keto diets to be restrictive if they don’t follow a cyclical plan with carb-loading days. Planning is everything. Whether you follow carb cycling or keto, consult a healthcare provider or nutritionist to tailor the diet to your needs.
- Both diets come with possible side effects. The keto diet can lead to the ”keto flu,” a short-term group of symptoms including headache and fatigue.