Longevity hacks

Scientists find the best time to eat protein for muscle growth

Getting swole can be a matter of meal timing.


American eating habits get bashed for over-indulging in ultra-concentrated sugar and refined wheat, but we might actually be on to something with one diner staple: bacon and eggs for breakfast.

When it comes to building muscle mass, breakfast is key. In a new study published in Cell Reports, researchers from Waseda University in Japan discovered that the timing of eating protein does make a difference in growing big and strong.

Through an analysis of “chrononutrition” — the relationship between our circadian rhythms and the nutrients we take in — the study team found both mice and people were able to maximize their muscle growth simply by eating protein-rich foods earlier in the day.

LONGEVITY HACKS is a regular series from Inverse on the science-backed strategies to live better, healthier, and longer without medicine. Get more in our Hacks index.

HOW THIS AFFECTS LONGEVITY — Maintaining muscle strength is key to being fit in adulthood and staying active into old age. Muscles aren’t just for show: They play a crucial role in keeping our body working the way it’s supposed to.

From replacing amino acids in crucial organs (which we can replenish with dietary protein) to helping the body repair itself in states of extreme stress like cancer or traumatic injury, we rely on muscles.

Protein, in turn, is what repairs and builds muscle. More muscle mass means more resting energy and more calories burned.

Plant-based proteins are a good way to fit more in for breakfast and were part of the foods consumed in the study.

Getty / carlosgaw

WHY IT'S A HACK — Researchers were able to deduce the right time to get in that extra protein, by tapping into something called clock genes.

These are genes related to our circadian rhythms: They help regulate our body’s internal clock, which determines the ebbs and flows of certain bodily functions throughout the day.

For example, we release melatonin at night when it’s time to sleep, and cortisol at the start of the day. The same kinds of patterns dictate when our body is more likely to better absorb nutrients like protein.

While it’s known people who eat protein evenly distributed throughout the day have better grip strength and higher muscle mass compared to those who do not, this is one of the first studies to link a diet specifically skewed toward more protein early in the day to a higher skeletal muscle mass and better grip strength.

Compared to the group who ate more protein at dinner, the women in the study with protein-rich breakfast didn’t seem to be exercising more — suggesting that the difference in muscle mass really may have come from protein timing.

Okay, so maybe your legs won’t look exactly like this with a protein-rich breakfast — but it can’t hurt either.

Getty / AFP / Stringer

SCIENCE IN ACTION — This multi-part study looked at the effects of protein timing in both mice and humans.

They fed two groups of mice twice a day: One group ate more protein at breakfast, and the other at dinner. After inducing muscle regrowth (or hypertrophy) in one leg of mice in every group (by removing parts of the leg muscles), the mice in the breakfast protein group grew muscles in that leg that were larger than the dinner protein group.

The two groups of mice (each including a breakfast and dinner group) were fed slightly different percentages of protein as a fraction of their diets. Surprisingly, it was mice in the lower protein group who ate more protein at breakfast who gained more muscle than the higher-overall protein dinner group.

This suggested that the timing of the protein played a role. Branched-chain amino acids (BCAAs), nutrients the body pulls from proteins, especially influenced the building of muscle mass.

To make sure that circadian rhythms were involved, the researchers engineered genetically modified mice without a key clock gene related to muscles. When they tried to repeat the same experiment, they found the effect was erased — the circadian rhythm was needed to maximize muscle growth with protein timing.

The study team also gave a food questionnaire to women, asking what categories of proteins they ate generally (for example, plant-based proteins versus proteins from meat) and when. They selected two groups based on their answers about their normal eating habits:

  • Women who ate more protein for breakfast than dinner
  • Women who ate more protein at dinner than breakfast.

In turn, the women in the breakfast group had more muscle mass and better grip strength. Apart from these changes, there were no significant differences across the two groups when it came to weight, fat mass, physical activity, and total protein intake. The higher the “skeletal muscle index” — essentially the amount of muscle in arms and legs relative to height — the higher their ratio of breakfast protein to total protein.

Sounds like a good excuse for some start-of-the-day eggs.

HACK SCORE OUT OF 10 — 🥓🍳🥓🍳🥓 (5/10)

Related Tags