How Effective is Carbohydrate Cycling?

By Brett Benson

What is Carbohydrate (Carb) cycling?

          Carbohydrate cycling is a dietary approach to manipulate carbohydrate intake in order to lose fat and break through weight loss plateaus. This method can be done on a daily or even weekly basis alternating between high carbohydrate and low carbohydrate days. Now, this diet isn’t for everyone and some individuals such as sprinters, long distance runners, weight lifters, and many other athletes will require higher amounts of carbohydrates more frequently for improving their performance. On the other hand, someone who is simply trying to lose weight can also take advantage of this approach to see a noticeable difference in their overall health.

This diet can be very useful for improving body composition, but there are limited studies examining this topic in great detail or for long durations. There is also no set limit on what exactly is considered “low carbohydrate” or “high carbohydrate” with regards to the amount of carbohydrates consumed daily. This is largely based on many criteria such as a person’s training schedule, body fat level, type of training, and body composition goals to name a few. In theory, training days are going to require a higher carbohydrate intake and rest days would have a low carbohydrate intake. None the less, there are a few benefits of carbohydrate cycling which include improving exercise performance, fat metabolism, and insulin sensitivity.

Effectiveness on exercise and fat loss

     For athletic performance, high carbohydrate days can be beneficial in reducing muscle break down and increasing the anabolic effect post resistance exercise. Since glycogen is depleted during exercise, consuming higher amounts of carbohydrates becomes crucial during the post exercise phase (Børsheim et al., 2004). Simple carbohydrates, for example, can be digested rapidly in the body and have the ability to help replenish muscle and liver glycogen after exercise. The most common simple carbohydrates are found in fruit as well as processed and refined foods like white rice, white bread, candy, sugary cereal, and even soft drinks. Combine with protein, these simple carbohydrates can increase insulin levels and dramatically help prevent muscle break down to promote faster recovery from workouts.
           Individuals looking for ways to facilitate fat loss can take advantage of including more low carbohydrate days into their weight loss program. Reducing the amount of carbohydrates can stimulate glucagon production, which raises blood sugar when it falls below normal levels. This will cause the body to begin breaking down glycogen and ultimately using fat predominantly for energy in the long-term. In one study by The American Association for Cancer Research, the participants following a low-carbohydrate diet for two days per week saw on average about 9 pounds of weight and body fat loss over 4 months (2011). Like this study, the ultimate goal of carbohydrate cycling is to be in a calorie deficit for stimulating fat metabolism and improving body composition.

Improving Insulin Sensitivity

   Insulin resistance occurs when the cells in the muscle, fat, and liver are resistance to the hormone insulin causing an increase in blood sugar. This requires the pancreas to produce more insulin than normal to help the blood sugar enter the cells. As individuals become overweight and obese over time this becomes a major issue especially with the prevalence of developing type two diabetes in this population. During a 16-week study, a group of overweight/obese adults who consumed the lower carbohydrate diet compared to lower fat diet lost more total fat mass (4.4%) and had improvement in glucose metabolism (Grower & Goss, 2015). This finding is significant because individuals with type two diabetes are commonly known for having insulin insensitivity or resistance. Another study showed that overweight women in an intermittent energy and carbohydrate restriction group had greater fat loss and improved insulin sensitivity compared to the daily energy restriction group (Havie et al., 2013). These studies show that carbohydrate cycling can play a big role in increasing insulin sensitivity within the body, but a well balance diet is also key for improving health and well-being.  

Take Away

          Carbohydrate cycling is more flexible than most diets which can be restrictive when it comes to eating. It is important; however, to choose carbohydrate foods that are higher in fiber like whole grains, fruits, vegetables, and legumes to help balance blood sugar levels and improve insulin sensitivity and reduce resistance. These foods are also high in a variety of vitamins and minerals, which are important for their numerous roles in the body. In addition to using carbohydrate cycling, it is important to consume adequate amount of protein while in a calorie deficit to prevent loss of lean body mass. Balancing low and high carbohydrate days on carb cycling may be beneficial both physiologically and psychologically for most people. The bottom line is that carbohydrate cycling can have a significant impact on health, but further research is needed to examine its effects long-term.

References

American Association for Cancer Research. (2011, December 8). Intermittent, low-carbohydrate diets more successful than standard dieting, study finds. ScienceDaily. Retrieved September 9, 2018 from www.sciencedaily.com/releases/2011/12/111208184651.htm

Børsheim, E., Cree, M. G., Tipton, K. D., Elliott, T. A., Aarsland, A., & Wolfe, R. R. (2004). Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise. Journal of Applied Physiology,96(2), 674-678. doi:10.1152/japplphysiol.00333.2003

Gower, B. A., & Goss, A. M. (2015). A Lower-Carbohydrate, Higher-Fat Diet Reduces Abdominal and Intermuscular Fat and Increases Insulin Sensitivity in Adults at Risk of Type 2 Diabetes. The Journal of Nutrition, 145(1), 177S–183S. http://doi.org/10.3945/jn.114.195065

Harvie, M., Wright, C., Pegington, M., McMullan, D., Mitchell, E., Martin, B., … Howell, A. (2013). The effect of intermittent energy and carbohydrate restriction v. daily energy restriction on weight loss and metabolic disease risk markers in overweight women. The British Journal of Nutrition, 110(8), 1534–1547. http://doi.org/10.1017/S0007114513000792