LOW-CARBOHYDRATES DIET RESEARCH | MUSCULAR DEVELOPMENT

Low-Carbohydrate Diet Research

The Impact of Dietary Carbs on Muscle Recovery & Free Testosterone

The mission of MD is to be the leader in the field of cutting-edge research, we want to give you all the tools (i.e., knowledge) you need to become a successful bodybuilder, and it’s up to you to decide what diet works best for you. These articles are not intended to bash any particular diet, but to educate and inform the reader as to what experts have reported about the role of diet and performance.

Low-Carbohydrate Diets Impair Muscle Recovery in Weightlifters

             Recovery from resistance exercise is paramount for continual gains in strength and size. Researchers from the University of Rhode Island were interested in the role of carbohydrates and how it impacted muscle recovery in weightlifters. 

             This study was a randomized two-trial experiment with subjects assigned to a low-carbohydrate and a higher-protein diet (226 grams of carbohydrate, 103 grams of protein, and 67 grams of fat) or a high-carbohydrate and a lower-protein diet (343 grams of carbohydrate, 85 grams of protein, and 62 grams of fat). Both diets were isocaloric. 

             Subjects were put through a bout of maximal eccentric leg exercise and subsequently followed after the eccentric exercise in order to measure soreness, protein synthesis, and enzymatic markers of muscle damage. In the study, the low-carbohydrate group showed the largest decrement in muscle strength after eccentric exercise and therefore, it would appear that low carbohydrates have a negative impact on muscle recovery after eccentric exercise. 

             This study suggests that a diet high in carbohydrates (at half of total calories), when protein exceeds the recommended daily allowance, will increase whole-body protein synthesis and reduce muscle strength loss and enzymatic activity during recovery from eccentric exercise. Therefore, dietary carbohydrate, as opposed to protein, may be the more important nutrient when the novice weightlifter is recovering from muscle damage. Finally, the increase in dietary carbohydrate must be at least five days in length and be accompanied by a protein intake above the RDA in order to be effective. 

Reference:

             Benjamin, L., Blanpied, P., Lamont, L. Dietary Carbohydrate and Protein Manipulation and Exercise Recovery in Novice Weightlifters. Journal of Exercise Physiologyonline, 12(6)2009. 

 Dietary Carbohydrates Impact Free Testosterone after Training

             Reducing dietary carbohydrates has been found to have an impact on circulating hormones, mainly increasing GH and also cortisol levels. The elevation of these hormones has a unique impact on reducing body fat, as many studies using low carbohydrates have reported greater fat loss. 

             Studies as early as 1979 found that subjects on a low-CHO diet (daily caloric intake = 11.5 percent CHO) for several days had elevated levels of fuel-mobilizing hormones, compared to subjects on a high-CHO diet (daily caloric intake = 77 percent CHO). 

             One question is that if low-carbohydrate diets can raise testosterone, what happens to free testosterone production? Researchers from the University of North Carolina examined the role of carbohydrate’s impact on free testosterone production. Athletes were assigned to a low-carbohydrate diet (30 percent) or a high-carbohydrate diet (60 percent) for three days in conjunction with intense cycling for three days. Both groups were fed the exact same amount of calories. The cyclists trained for one hour intensely for three days and then had serum blood markers analyzed. 

             The key finding in the study was that the resting free testosterone decreased from day one to day three in the low-carbohydrate group, while there was no change in the high-carbohydrate group throughout the three-day intense training sessions. So the big question is: How did the low-carbohydrate group and intense training lower testosterone? 

             The researchers speculated that the increase in cortisol from the low-carbohydrate group decreased testosterone as the free testosterone dropped by 36.1 percent and cortisol increased by 14.8 percent. The authors suggested that the combination of intense training in a glycogen-depleted state exacerbated cortisol levels, which resulted in a suppression of testosterone. Considering that this was an acute study (three days), a longer-term study may be useful to know the role of carbohydrates and how they impact testosterone production; the subject requires further investigation.

Reference:

            Amy R. Lane, Joseph W. Duke and Anthony C. Hackney. Influence of dietary carbohydrate intake on the free testosterone: cortisol ratio responses to short-term intensive exercise training. European Journal of Applied Physiology. E-publication, ahead of print.