You may have heard of carb cycling in the context of body building or athletic training, but what exactly does it mean? Simply put, carb cycling involves planned changes in eating that involve alternating between high and low carb days. Easy enough, but what about keto cycling? Well, keto fam, keto cycling is a specific form of carb cycling in which your body goes in and out of fat burning mode. Confused yet? Don't worry, we've Let’s explore!
The majority of carb cycling research pertains to athletes and is focused on enhancing performance or body composition. Endurance athletes have traditionally used carb cycling to maximize energy stores for competition, first depleting carbohydrate stores during periods of low carb eating and then replenishing them with periods of higher carbohydrate eating. The goal is to maximize carbohydrate storage in the muscles and liver (glycogen) and train the body to use fat as an alternative fuel source for energy so in competition the athlete is not limited to relying solely on carbohydrates. More recent research has shown that this does not always translate into increased performance.
Body builders and athletes participating in sports where achieving a specific weight is crucial (ex. wrestling) have also used carb cycling, with a goal of gaining muscle, burning fat and making weight.
Carb cycling is also sometimes used, as a method to restart weight loss, by those who are frustrated when they reach a weight loss plateau.
There are many different “how to’s”, yet no official protocol, but most carb cycling plans include:
- High carb days: carbs are ~50% or more of total calories
- Low carb days: carbs are ~25% or less of total calories
- Some also include a “moderate” carb day which is somewhere in between the high and low
Ketosis is achieved when the body depletes carbohydrate stores and starts using fat for energy. Keto cycling is a specific form of carb cycling in which your body goes in and out of ketosis, it typically involves sticking with a carb-restricted keto diet five to six days a week and having a higher carb day or two where you plan for a higher intake of carbohydrates. When following the keto diet, some recommend not attempting “cycling” until your body is fully adjusted to ketosis which varies for all but could be over 30 days. With keto cycling the low carb cycles are low enough and last long enough to induce ketosis.
To get into ketosis carbs generally need to be 10% or less of total calories. This is still under the 25% threshold to be considered “low carb” but on the lower end. For the same 2000 calorie diet this would mean 200 calories or fewer coming from carbs, or 50g or less. And many people require fewer carbs to get into ketosis – around the 20-30g range. This extremely modest amount of carbs on a keto diet typically comes from vegetables like zucchini and leafy greens and some nuts and seeds.
When planning higher-carb days for keto cycling it may be best to use good quality carbs like sweet potatoes, berries, lentils, and whole grains like quinoa versus hitting the doughnut shop, as the switch to using carbs for fuel may be less difficult for the body with these healthier carb choices. Why? Despite the change in amount of carbohydrates, the body needs good quality fuel to function optimally and good sources of carbs break down slowly and are loaded with nutrients (vitamins, minerals, fiber, phytonutrients).
Another consideration is that, although research is limited, a recent exploratory study suggested potential damage to the lining of the arteries in healthy individuals who indulge in ‘cheat days’ while on keto. Damaged arterial lining increases likelihood for plaque buildup and inflammation within the blood vessels –potentially increasing risk for heart disease and stroke.
Carb Cycling vs. Keto Cycling
While keto-cycling typically involves a succession of low carb days with 1-2 higher carb days, traditional carb cycling may alternate high and low carb days back to back. Those who choose carb and keto cycling for exercise performance, typically pair the higher carb days with exercise. Research shows that carbs can enhance muscle recovery (breakdown and rebuilding) and restore glycogen stores to better prepare the body for the next workout.
The body uses more carbohydrates during high intensity exercise so it makes the most sense to pair higher carb days with high intensity rather than endurance exercise. When exercising on low carb days, opting for endurance or lower intensity activities like yoga or pilates is recommended. The body is better able to use fat for energy needs during these activities.
The key difference between carb cycling and keto cycling is that carb cycling does not bump you in and out of ketosis.
While the concept of dietary cycling is fairly new, there are some studies that have suggested a potential benefit to the mechanism behind maximizing carbohydrates and training the body to use fat for fuel but more research is needed. Following are some of the possible benefits:
- Some research shows that carb cycling can be an effective way to train the body to be flexible in using fat and carbs for fuel, and to increase stored carbohydrates (glycogen)
- Carb loading after a workout increases glycogen (carbohydrate) stores. Exercise performance is reduced when glycogen stores are depleted.
- Some research shows that carb cycling improves endurance and intensity of exercise
- Improvement in muscle repair and building after strenuous workouts. These benefits apply to keto cycling as well.
- Although research hasn’t explored the theory in detail, some proponents of keto cycling believe that long term carb restriction, can interfere with hormones that are important for healthy body composition like thyroid hormone and insulin and cycling could potentially help with maintaining balance.
- When considering weight loss, cycling could be beneficial as long as a calorie deficit is maintained.
- Lastly, and probably the most important from the perspective of a dietitian, is that because of its restrictive nature the keto diet can be difficult to stick with. So keto-cycling could allow for flexibility making it a more sustainable diet choice for the long term.
Is Carb or Keto Cycling Recommended?
Carb cycling can be used to improve exercise performance and metabolic flexibility (alternating between fat and carbs for energy), but it involves an investment of time and energy and can be rather complicated.
If you’re on a keto diet and your performance in the gym is not lacking and your energy level is good, you might want to continue the classic ketogenic diet and focus on nutrient rich foods – leafy greens, wild fish, nuts, seeds, olive oil, grass fed meat and eggs. – versus complicating things with keto cycling.
However, if you’ve hit a plateau with weight loss or at the gym and aren’t able to complete and recover from intense workouts you might ponder giving cycling a try and see if it’s a good fit to reach your health goals. Because of the lack of a set protocol and the complexity of switching your body back and forth from using carbs to fat for fuel, working with a dietitian who can help you navigate the process is recommended.
On a closing note, I always like to remind people that when it comes to dietary choices there is not a one size fits all protocol. So if cycling is the key to help you stick with a healthy and sustainable dietary plan that makes you feel and perform at your best, then go for it!