Among all the myths in the world of health and fitness, carbohydrates are probably the most confusing. For decades they have absorbed harsh criticism, sometimes even exaggerated – They were accused of causing high cholesterol levels, increased blood pressure and of course, obesity.
At the same time, professional athletes such as powerlifters and bodybuilders have been using carbohydrates in a calculated way for years – Synchronizing intake according to their training routine, planning varying carbohydrate consumption throughout the week and using them to become stronger, bigger and more impressive. The same food group – But two completely different perspectives.
The question is: Who is right? Researchers in a new study examined together many existing studies on the subject, in order to obtain a clearer and more accurate picture regarding the effect of carbohydrates, while they focused on one question: Does eating carbohydrates in high quantities really lead to significant muscle growth?
The study, which was published in Springer Nature, sought to examine the effect of carbohydrate consumption on increasing muscle mass. The researchers noted that until now the isolated effect of carbohydrates on muscle had not been systematically examined, outside the context of ketogenic diets.
In order to answer the question, the researchers reviewed randomized controlled studies that compared between different levels of carbohydrates during about 8.5 weeks of resistance training. The studies were required to measure changes in muscle size directly, using measures such as muscle thickness, cross-sectional area, or scans of lean muscle mass – And not using a measuring tape or caliper.
The researchers focused on examining the effect of carbohydrates alone. They included studies in which there were intentional changes in the amount of carbohydrates, but excluded studies in which protein amounts or other supplements were also changed, so that the findings would reflect only the effect of carbohydrates. In addition, the participants were required to be healthy adults aged 18–65, without neuromuscular diseases, so that the findings would reflect the effect on a population of healthy athletes in general.
The findings were clear: No significant difference was found between high carbohydrate consumption and low carbohydrate consumption when it comes to increasing muscle mass. However, the researchers note that the study is not perfect. Most of the studies that were included lasted only about two months, a relatively short period of time when it comes to measuring significant muscle growth. Beyond that, many of the studies examined change in lean body mass instead of in the muscle itself. Lean body mass includes muscle but also water, bones and other tissues, and therefore it is not an accurate measure of pure muscle growth.
Therefore, although carbohydrates are an essential nutritional component and are not “evil” as they were described in the past, the study raises important questions regarding their direct effect on muscle growth. Trainees who want to increase their muscle mass still need to focus on a balanced training program and sufficient protein intake, and to see carbohydrates as another tool to support energy and performance. Carbohydrates are not the absolute solution for muscle growth, but they are an important part of the bigger picture of proper nutrition and physical fitness.