If you dieted in the 1990s or early 2000s it’s highly likely you tried a low-carb diet. Atkins, South Beach and the Zone Diet are just a few of the many low-carb diets that proliferated during these years. These are still very popular diets today, although many health and nutrition professionals have moved towards a more moderate approach when it comes to carbohydrate consumption and weight loss.
One of these more moderate approaches is an adaptation of a low carb diet for short periods (also known as a ketogenic diet) coupled with periodic higher carb days. You might guess from the name how this works: you “cycle” your intake of carbs, alternating between “boost” days when you eat carbs, and “burn” days, when you restrict carb intake.
While the public may be just becoming aware of the carb cycling approach to weight loss, the bodybuilding community has long used this method to reach muscle gain and fat loss goals. The science behind carb cycling has to do with the way that your body produces, uses and stores energy. Our bodies use the food we eat as energy, and that food is classified into three groups of macronutrients: proteins, carbohydrates, and fats.
Carbohydrates — either broken down in the body as glucose (quick energy) or stored (in a very limited capacity) as glycogen in the muscles and liver — are the most easily and readily accessible forms of energy, so our body typically goes to them first. The rationale behind low carb diets is that when you restrict carb intake, your body must turn to fat stores for energy – thus “burning” fat, which is what most dieters are aiming to lose.
Low carb diets have been shown to work for fat loss, however research has also shown that extended periods of carbohydrate restriction can lead to depressed activity in the hormones that regulate the metabolism, and thus, over time, a slowing of the metabolism. So, while you may lose weight in the short term on a low carb diet, in the long run you could be reducing the efficiency of your metabolism.
When you follow a carb cycling program, your body never gets to the point when your metabolism-regulating hormones would get out of whack. The alternating low and high carb days serve to keep the metabolism in relative balance and also prevent the “crash” – physical and psychological – often associated with low carb dieting.
In a carb cycling diet, after a low carb day, the body’s glycogen stores (which, again, are very limited) become depleted and the body resorts to burning fat. On the following high carb day, the carbohydrates consumed are used to replenish these stores. Ideally, on the high carb days, you consume enough carbs to replenish glycogen but not so many that there are carbs left over for your body to store as fat.
Another benefit of the high carb days is added energy for exercise that you might not otherwise have on an entirely low carb diet. You can see how alternating this way would, when done correctly, provide the body with just the amount of carbs to keep its metabolic processes running normally, while preventing excess carbs that would otherwise be turned to fat.
It’s important to note that just because carb cycling includes so-called “high carb” days, these should not be taken as “cheat” or “free” days. Choose the best carbohydrates for your body – the ones that it will not only use most efficiently but also those that have other nutritional benefits. These include healthy starches like whole grains, brown rice, beans and legumes, and starchy vegetables such as potatoes and squash.