Protein is essential for body growth and muscle building. However, protein metabolism varies depending on the body’s internal biological clock. Therefore, it is important to know how the distribution of protein intake during the day affects the muscles. Researchers from Japan have now discovered that consuming protein in the morning increases muscle size and function in rats and humans, shedding light on the concept of ‘Chrononutrition’ that deals with the timing of diets to ensure organ health.
Protein is an essential dietary ingredient that helps the body grow and repair itself. Consisting of long chains of amino acids, proteins promote the growth of skeletal muscle, the group of muscles that help us move. People have been aware of the benefits of protein for a long time. However, recent studies have shown that having the right amount of protein at the right time of day is essential for proper growth. This is called ‘Krononutricion’, in which when what you eat is just as important as what AND like you eat
The reason behind this is the body’s internal biological clock, called the ‘circadian rhythm’. This rhythm is followed by all cells and controls life functions like metabolism and growth. Interestingly, the digestion and absorption of proteins has been found to fluctuate day and night according to this hour. Moreover, previous studies have reported that protein intake in the morning and lunch promotes skeletal muscle growth in adults. However, details on the effect of protein intake time on muscle growth and function have remained elusive to date.
Fortunately, researchers from Waseda University, led by Professor Shigenobu Shibata, recently tried to understand the effect of the distribution of daytime protein intake on muscle. They fed laboratory mice two meals a day containing high (11.5% in proportion) or low (8.5% in proportion) protein concentrations. The researchers noted that protein intake in the morning spurred an increase in muscle growth, determined by the assessment of induced hypertrophy of the soleus muscle of the foot when compared to the effects of protein intake at dinner. Specifically, the ratio of muscle hypertrophy determined against control muscle growth was 17% higher in rats fed 8.5% protein at breakfast than in rats fed 11.5% protein at dinner, despite the previous group consumed a low portion of protein. They also found that taking a type of protein called BCCA, short for branched-chain amino acids, at the beginning of the day specifically increased skeletal muscle size.
To confirm the association of these effects with circadian rhythm function, the following researchers created ClockΔ19 mutant knockout mice or muscle-specific mice that did not have the genes that control the biological clock. They repeated diet distribution experiments in these mice, but did not notice similar muscle changes, which confirmed the involvement of the circadian rhythm in muscle growth in the context of protein intake.
Excited about the findings of their study published in a recent issue of Cell Reports, Prof. Shibata emphasizes, “A protein-rich diet at an early stage of the daily active period, which is in the morning, is important to maintain skeletal muscle health and increase muscle volume and grip strength.”
To check if their findings were applicable to humans, the team recruited women into their study and tested whether their muscle function, determined by measuring skeletal muscle index (SMI) and grip strength, changed over time. consumed of protein-rich diet. Sixty women aged 65 and over who received protein in the morning rather than at dinner showed better muscle function, suggesting the possibility that the findings were true among species. Moreover, the researchers also found a strong correlation between SMI and the percentage of protein intake in the morning compared to total protein intake throughout the day.
Prof. Shibata hopes the findings of their study will lead to a widespread modification to the current diet regime of most people across Western and Asian countries, who traditionally consume low amounts of protein in the morning. He therefore emphasizes, “For people, in general, the protein intake in the morning averages about 15 grams, which is less than what we consume at dinner, which is approximately 28 grams. Our findings strongly support changing this rate and consuming more protein in the morning or at breakfast time. “
It seems, a simple change in our diet regimen could be our key to ensuring healthy muscles!
- Shinya Aoyama, Hyeon-Ki Kim, Rina Hirooka, Mizuho Tanaka, Takeru Shimoda, Hanako Chijiki, Shuichi Kojima, Keisuke Sasaki, Kengo Takahashi, Saneyuki Makino, Miku Takizawa, Masaki Takahashi, Yu Tahara, Shigaki Shimobas diet in daily meals affects skeletal muscle hypertrophy through muscle clock. Cell ratios, 2021; Volume 36 (1): 109336 DOI: 10.1016 / j.celrep.2021.109336