How Carbs Help Build Muscle: Lessons from Mr Universe Mark Taylor

High-protein, low-carb eating plans have traditionally been viewed as the benchmark for gym users and bodybuilders looking to add muscle while shedding fat. Yet one bodybuilding champion has demonstrated that a chiselled physique may not depend on this approach alone.

Mark Taylor, a 52-year-old bodybuilding veteran who secured the sought-after "Mr Universe" title in 2023, recently said that embracing carbohydrates was central to his achievement.

Taylor spent years strictly following the conventional high-protein, low-carb diet, but was constantly exhausted. Only after moving away from that mindset and restrictive plan - placing greater emphasis on carbohydrates and higher calorie intake - did he eventually realise his ambition.

Although this method may appear to challenge accepted wisdom, what does the evidence suggest?

Building muscle with nutrition

Training is essential if you want to improve your physique and build muscle; there is no substitute for it. Muscle is developed through progressive overload, whether that means progressively lifting heavier weights or completing more repetitions or sets of an exercise.

Provided the training stimulus is sufficiently challenging, adaptations that occur while you recover can produce progress over time.

More precisely, muscle growth depends on the balance of two ongoing processes: "muscle protein synthesis", in which new muscle tissue is created or repaired, and "muscle protein breakdown", in which muscle tissue is broken down. Since both processes take place continually, the speed and balance of each will determine overall progress.

Well-planned nutrition, combined with organised training, helps support these processes. Protein is vital because it supplies amino acids, including leucine, which are the raw materials needed to build muscle.

Research indicates that total daily protein consumption, along with consuming enough calories, may matter most for overall muscle gains. Essential fats, vitamins and minerals also play a part in building muscle. In contrast, eating fewer calories than your body requires can have a negative impact on training.

Studies also show that having 20 - 40 grams of 'fast releasing' protein, such as whey protein, after exercise may boost muscle protein synthesis in the short term. Many gym-goers additionally have 'slow releasing' proteins, including casein protein, before bed to meet daily protein targets or improve recovery.

Where carbohydrates fit into muscle building

Some research finds that consuming carbohydrates with protein after exercise can increase muscle protein synthesis. Other studies, however, find no such advantage over protein on its own. Amino acids are crucial to this process, while carbohydrates do not supply these building blocks and therefore cannot directly stimulate muscle protein synthesis.

Carbohydrates may, nevertheless, affect how much muscle protein breakdown takes place. They prompt the body to release insulin, a hormone that has been shown to limit protein breakdown.

Protein also affects insulin production and can create a comparable response. Therefore, if you consume enough protein after training, it could be argued that extra carbohydrates are unnecessary from a muscle-building standpoint. So what accounts for Taylor's results?

Many bodybuilders follow a 'bulking' phase, raising their daily calorie intake by around 15 percent or more in an effort to gain muscle mass. This is then followed by a 'cutting' phase, in which body fat is strategically reduced to make the muscles more noticeable. A low-carb strategy can encourage fat loss and produce a lean physique, which is why it appeals to many gym enthusiasts and bodybuilders.

However, low-carb diets also provide less energy, potentially causing poorer immunity, increased fatigue and reduced performance. They may disrupt menstrual function in women and reduce testosterone, which is necessary for muscle development, particularly in men. For some people, these widely used cutting methods may therefore be counterproductive.

Carbohydrates, glycogen and gym performance

Carbohydrates provide energy as glucose, which is stored within muscles as glycogen for use later. Gym sessions can be demanding, so glycogen stores are used to provide fuel more quickly.

This makes it possible to train at a higher intensity, indirectly affecting muscle protein synthesis. Failing to replenish carbohydrates while repeatedly training with low glycogen may impair not only the muscle-building process but also training outcomes overall.

Choosing carbs for energy and recovery

The type of carbohydrate selected matters too. Taylor chose sweet potatoes and porridge, meaning his diet took a lower-glycaemic approach.

The glycaemic index (GI) measures how rapidly the carbohydrates in a food raise blood sugar levels. Low-GI foods, such as porridge, release energy more slowly. As well as influencing mood, this can provide sustained energy throughout the day, helping to counter fatigue and supporting other health outcomes, including lower blood pressure.

While low-GI foods are useful during the day, evidence shows that high-GI options, such as white pasta, bagels and granola, can help restore glycogen rapidly after demanding or lengthy training. Combining low-GI and high-GI foods across the day may therefore be a useful strategy for training and recovery.

Whether you are an athlete or not, gaining muscle mass takes effort, and diet can affect the outcome. Providing muscles with protein while using carbohydrates to fuel training could be a more effective route to reaching your goal.

If you are not getting the results you want, as Taylor was not, carbohydrates may be the part of the puzzle that is missing.

Justin Roberts, Professor of Nutritional Physiology, Anglia Ruskin University; Henry Chung, Lecturer in Sport and Exercise Science, University of Essex, and Joseph Lillis, PhD Candidate in Nutritional Physiology, Anglia Ruskin University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.