What’s the buzz?
Carb cycling is the latest go-to diet to boost athletic performance and burn fat.
What does the science say?
As the primary fuel for our muscles and brain, carbohydrates are the limiting factor when it comes to endurance exercise and have also been shown to play an important role in short-duration, high-intensity exercise. Yet, in an age where carbs are the scapegoat for everything from weight gain to brain fog, many people, including athletes, are looking for ways to cut back. But before you say bye-bye to bread, know this: cutting all carbs can lead to fatigue, and removing them from your diet it isn’t as easy at it sounds. When carbohydrate intake is too low, survival mechanisms kick in that cause us to crave all the bread and sugar, which is why many people struggle to follow low-carb diets.
Enter carb cycling — which, sadly, is not a term for bicycling while eating spaghetti — a new(ish) diet that some athletes are turning to as a way to improve performance while reducing carbohydrate consumption. In many cases, carb cycling is also used in an attempt to lose body fat without sacrificing muscle mass (weight loss is typically a loss of a mix of muscle, fat, and water). Sometimes referred to as “train low, perform high,” this diet is based on a theory that starving muscles of carbohydrates trains the body to use fat as fuel more often, which should result in a slower use of carb reserve during performance. Pair that with a little bit of carb loading (aka perform high) and this, in theory, could lead to less chance of “bonking” (running out of energy, or fuel, in the midst of exercise) due to lack of carbohydrates, since our bodies can store more fat than carbs.
Some protocols cycle carbs daily based on exercise demands (higher carbs on high activity days and low-carb on rest days), whereas others suggest eating very low carbs for several weeks and then have “refeeding” days every several weeks or month(s). Either method requires very close monitoring of carbohydrate intake along with training and performance schedules, which may be second nature for some athletes, but can add a lot of work or others.
So, you get to have your (low) carbs and eat them too — sounds like the perfect solution, right? Not so fast. Carb cycling has practically no scientific research to support it. While low-carb, high-fat diets (a key part of the carb cycling theory), have shown a glimpse of promise among elite athletes, there appears to be a significant adaptation period, and they still may lead to fatigue and poorer performance. Many personal reports do suggest that carb cycling boosts performance and can help with fat loss, so its possible that the research just hasn’t caught up yet. For those athletes prone to eating disorders or have a history of disordered eating, carb cycling is not recommended as it requires paying very close attention to macronutrient intake, which can lead to unnecessary stress and, in some cases, obsessive behaviors. However, for a diligent athlete looking to enhance his or her body’s ability to rely on fat for fuel, carb cycling may be more effective and require less adaptation time than a very low-carb diet like the ketogenic diet.
What’s the takeaway?
Carb cycling is not well researched and can be a difficult diet to follow. However, anecdotal evidence suggests possible performance and fat-loss benefits. If you’re thinking about trying carb cycling, seek out a registered dietitian specializing in this regimen to help you tailor a program that meets your goals and who can ensure you don’t miss out on important nutrients found in many carbohydrates.
Read more about the pros and cons of carb cycling here.