How to Solve the "Eating Stress" of Bodybuilders: Amino Acids as a Choice to Optimize Muscle Synthesis During the Bulking Phase

Bodybuilding, which aims to maximize muscle size and create a visually appealing physique, involves not only training but also a meticulously calculated nutritional strategy. In particular, during the "bulking phase" when the body is being enlarged, a massive amount of food must be consumed, and many athletes struggle with not being able to eat as much as they would like, or with the stress of eating.

This time, we interviewed Professor Jun Yasuda, who supports the prestigious Tokai University Bodybuilding Club, which has a record of winning the team championship at the All Japan Student Bodybuilding Championships, about how to reduce the nutritional burden during the bulking phase. Taniyama from Ajinomoto Co., Inc.'s Sports & Health Nutrition Department will be the interviewer.

≪Contents of this article≫

• - The "eating stress" of bodybuilders during their bulking phase
• Why protein intake can lead to decreased appetite and energy deficiency
• ・EAAThe scientific mechanism by which essential amino acids support muscle synthesis

The difficulties of bulking: unimaginable amounts of food.

Taniyama:What kind of coaching does Professor Yasuda usually provide to the bodybuilding club members?

Yasuda:Essentially, their job is to "build muscle." My role is to support them in how to utilize nutrition within that framework. I get a lot of questions about how to use supplements. Various supplements are mentioned, such as protein, creatine, and amino acids. I examine them and propose nutritional strategies that fit the athletes' bodies and lifestyles.

Taniyama:When you think of bodybuilders, you probably imagine them eating an enormous amount of food.

Yasuda:As you said, the amount of food they eat is incredible. Basically, bodybuilders have a "bulking phase" to increase their body size and a "cutting phase" to prepare for competitions. The amount of food they eat during the bulking phase is tremendous; some athletes eat as much as 8 cups of rice a day.

Taniyama:You're going to eat 8 cups of rice?!

Yasuda:In addition to that, they also need side dishes, and they may take supplements, so I think they are a group that eats a very large amount of food.

The pitfalls of "protein": Risks of decreased appetite and energy deficiency

Taniyama:Many people imagine that bodybuilders consume a lot of protein, but is that actually true?

Yasuda:There's a common image of "bodybuilders = protein," and I personally thought they consumed a lot of protein. However, bodybuilding is an individual sport, and in reality, each athlete has a different diet. Some athletes consume around 100g of protein a day, while some top athletes don't consume protein at all. However, among student athletes, it seems that most of them do consume protein.

That's why I believe that determining whether protein and supplements are truly necessary is the point I should intervene in, and that's what I focus on in my daily work.

Taniyama:Are there any precautions I should take when taking protein supplements?

Yasuda:Many athletes consume protein after training, but if they train in the evening, for example, consuming protein can suppress their appetite, making it difficult to get enough energy for dinner. This is a common problem across all sports, so please be careful.

If there is enough time before dinner, it is fine to take protein, but if you want to avoid affecting your meals, it is best to choose something that is easily digested and absorbed, such as carbohydrates or amino acids, and prioritize recovery after exercise. We have seen athletes who want to gain weight but suppress their appetite with protein and end up missing their important dinner, so this is something to be careful about.

Furthermore, protein has been reported to have an appetite-suppressing effect. Athletes who are good at gaining weight can eat a lot, but for athletes who struggle with gaining weight, protein is not a nutrient that promotes weight gain, but rather one that promotes weight loss. Therefore, we sometimes tell athletes who struggle with gaining weight to "keep protein intake to the bare minimum."

Furthermore, it's important to note that protein itself is a nutrient that is not easily converted into energy for weight gain. This is called DIT (diet-induced thermogenesis), where even if you consume protein, about 3% of it is consumed as heat, and only the remaining 7% can be used for weight gain.

On the other hand, with lipids and carbohydrates (sugars), the amount consumed is at most 10% or less, so protein can still be considered a nutrient suitable for weight loss. If the goal is weight gain, then avoiding this loss should also be considered.

Switching to EAA is the key to efficient weight gain.

Taniyama:Are there any other things besides protein that can be used to gain weight?

Yasuda:I believe amino acids are also easy to utilize. Weight gain is all about controlling your own appetite and ensuring you get enough food. While protein intake can easily lead to sustained appetite suppression, amino acid intake is less likely to cause this. Literature has also reported that amino acid intake results in less secretion of the appetite-suppressing hormone (GLP-1) than protein intake.

Taniyama:So, amino acid intake is important for bodybuilders too, right?

Yasuda:In fact, "essential amino acids" are a very important term in muscle building and bodybuilding. However, most supplements containing them are sold as "EAA (an abbreviation for Essential Amino Acid)." I think few athletes realize that protein and EAA are different things and that they should be used differently.

Scientifically speaking, EAAs are the most important for building muscle. Adding the remaining 11 non-essential amino acids to EAAs makes up "protein." While there's a strong general perception that "protein intake equals muscle building," for those who eat a balanced diet, supplementing with just the nine EAAs should be sufficient for muscle growth.

In fact, studies from the 2000s have shown that muscle synthesis through EAA intake is equivalent to that of protein. Therefore, the key point is to understand that "EAAs are the most important for muscle synthesis."

Furthermore, by replacing protein with a small amount of EAA, it is thought that muscle growth can be achieved efficiently by reducing the intake of protein, which has a high DIT (high energy loss), while increasing the intake of carbohydrates (sugars) and fats, which have a low DIT (low energy loss), while maintaining muscle synthesis capacity.

Taniyama:Thank you. I had a strong image of "bodybuilders = protein," but I learned that essential amino acids also have a positive effect on bodybuilders, which was very informative.

Yasuda:Among the bodybuilders I support, some are good at bulking up, while others are not. For those who struggle with bulking, it's especially important to consider the properties of protein, such as its appetite-suppressing effect and DIT (diet-induced thermogenesis).

If you're struggling to gain weight, instead of sticking to protein, why not try switching to EAAs (essential amino acids)? Amino acids can help reduce energy loss due to diet-induced weight loss (DIT) and lessen the impact on appetite, allowing you to eat properly and still build muscle.

Summary | Reducing the "eating stress" of bodybuilders

• Bodybuilders need to consume enormous amounts of food during their bulking phase.
• • Protein can sometimes lead to appetite suppression and energy loss.
• EAAs (essential amino acids) can reduce digestive burden and energy loss.
• • For efficient weight gain, consider using EAAs.

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For those who want to enhance the effects of muscle training with "small amounts, high efficiency," try "EAA-rich whey protein."

Professor Jun Yasuda, Lecturer, Department of Health Management, Faculty of Health Sciences, Tokai University

PhD (Sports and Health Sciences), Registered Dietitian, NSCA-CSCS

After completing her doctoral studies at the Graduate School of Sport and Health Science, Ritsumeikan University, she worked as a researcher at the National Institute of Sports Science, among other positions, before assuming her current position in 2023. Her research focuses on maintaining and increasing muscle mass, encompassing exercise and nutritional strategies, and she implements evidence-based findings into nutritional support in competitive sports settings.

Masanao Taniyama, Marketing Group, Sports & Health Nutrition Department, Ajinomoto Co., Inc.

During his student years, he dedicated himself to American football, experiencing firsthand the importance of physical training and conditioning. After joining the company in 2013, he worked in sales of household products before assuming his current position in 2019. He is involved in the development of sports supplements, utilizing his knowledge from competitive sports and research in product design.