If you’re trying to build muscle, you probably know it’s important to eat enough protein to meet your needs. Muscle is made out of protein, and exercise and physical activity cause us to break down the protein in our muscle.
Don’t you fret, though. While we break down muscle protein every single day, we also build it back up via muscle protein synthesis. Both feeding and physical activity increase muscle protein synthesis(MPS).
Muscle protein synthesis is also regulated by our circadian rhythms. A new paper looking at muscle protein synthesis and breakdown found:
- Muscle protein synthesis is under circadian control
- MPS is 50% higher during the day than night
- Even after controlling for feeding and activity, MPS was higher during the day
- Muscle protein breakdown was higher at night
Now, it’s important to point out that this study was in zebrafish and not humans. But zebrafish are actually a pretty good model for circadian rhythms in human muscle. They’re active in the daytime like us, their muscle is similar, and many genes causing pathology in muscle are conserved between us.
Fortunately, there are other studies that bolster this data. Generally speaking, the data seems to point pretty strongly in one direction.
Eating protein at breakfast and lunch are key to optimizing muscle mass.
Eating protein at breakfast or dinner: Which is better to build muscle?
Another recent paper looked at the effects of eating protein at breakfast or dinner in promoting muscle growth. Mice were fed a low protein meal or a high protein meal at lunch or dinner over differing amounts of total daily protein.
First off, they found that eating protein at breakfast led to greater muscle growth than eating it at dinner. Second, they found that mice consuming a high protein meal at breakfast actually saw a 17% increase in muscle hypertrophy compared to the group eating high protein for dinner. This, despite the high protein dinner group consuming more total protein(11.5% vs 8.5%) than the high protein breakfast group.
Next, they knocked out circadian clock genes which eliminated the differences between the groups. Therefore, this provides evidence supporting the idea that muscle protein synthesis is under circadian control. Additionally, eating protein earlier in the day is better to build muscle than later at night.
What makes this even more interesting is that mice are nocturnal, so their active phase is actually at night. As such, muscle protein synthesis is under circadian control, but it follows the active phase and not the day/night cycle.
Finally, the authors took a group of 60 women and split them up into 2 groups based on when they eat their protein. Half of the women ate higher protein at breakfast while half ate higher protein at dinner. Those who ate more protein at breakfast had a greater skeletal muscle index and better grip strength than those who ate it mostly at dinner.
While that data is observational and can’t prove causality, it further bolsters the idea that eating adequate protein early in the active phase is essential to optimizing muscle mass.
Breakfast is like Wu-Tang, it’s also for the children
Our next stop on the protein train is a study looking at nitrogen balance in children. Protein contains the element nitrogen, and is the only macronutrient that does so. As such, nitrogen balance refers to the balance between nitrogen lost and nitrogen gained.
In adults and children, our overnight fast puts us in a net catabolic state; protein breakdown outpaces protein synthesis, leading to negative nitrogen balance. So, in the morning, it’s important to turn the tide toward protein synthesis.
Consuming just 7g of protein at breakfast along with 18g at lunch was enough to offset the negative nitrogen balance caused by the overnight fast in children. Furthermore, greater protein intake at breakfast dose dependently increased nitrogen balance for the following 9 hours.
It’s important to point out that this jibes with what we discussed regarding circadian and behavioral rhythms in our last episode of The Health, Happiness, and Performance Show. Circadian rhythms drive behavioral rhythms, and aligning the 2 has a synergistic effect.
Conversely, misalignment leaves something on the table.
Alternate day fasting=muscle loss???
Another bit of evidence that eating protein earlier in the day comes indirectly from a study looking at the difference between alternate day fasting and daily calorie restriction for weight loss. The study lasted 3 weeks and people either ate calories to 75% of maintenance every day or fasted every other day, eating 2 days worth of food on the feeding day.
They found that both groups lost a similar amount of weight (4.2 lbs daily CR vs 3.52lbs ADF). However, the total amount of fat lost was much higher in the daily CR group(3.85lbs) than the ADF group(1.62lbs).
This means that ADF led to weight loss, but more than half of it came from lean body mass. Interestingly, in order to get the meal timings correct, people in the ADF group broke their fast in the later afternoon.
If this follows the above data whatsoever, the change in results was likely due to being in a prolonged period of protein breakdown in relation to protein synthesis. Assuming they woke at 8am and fasted until 3pm when they broke their fast, they spent 7 extra hours in net protein breakdown.
In essence, they maintained a catabolic state well past lunch.
To build muscle, you need to consume enough protein to offset your daily losses. But does the time we eat protein also make a difference?
Based on the data, consuming more protein earlier in the day puts us into a positive nitrogen balance earlier such that muscle protein synthesis can push us towards positive nitrogen balance. As a result, we spend a longer period of our day building muscle.
Of course, we can assume that this effect is either minor, or doesn’t pertain to humans. The problem is, the circadian variation in muscle protein synthesis/break down seems to be conserved in many species.
Truth be told, the anticipatory bump in muscle protein synthesis during the active period is a classic example of how circadian rhythms work. Sequestering muscle protein synthesis to the active period of the day when we are eating and being physically active makes sense. This sweet little trick will dramatically increase our chances of survival in the wild.
Both increase the rate of muscle protein synthesis, and MPS requires circulating amino acids from protein. They also both activate mTOR, which essentially functions as an anabolic switch.
If you’re a young buck trying to pack on muscle mass or an old fart trying to keep it as long as you can, you may want to look at shifting protein consumption earlier in your active period. In other words, don’t wake up at 6am and wait until noon to eat.
If you want to do something like ADF, skip dinner, not breakfast.