We all want to build lean muscle tone from the workouts we do at the gym, but according to a new study, the timing of when to eat protein matters, since our bodies metabolize different macronutrients at different times of the day. The findings lend credence to the idea that the timing of food is important, especially when it comes to building lean muscle mass.

This new study appears to answer the question once and for all: When is the best time to eat protein? The evidence shows that consuming protein earlier in the day, for breakfast or an early snack, is the key to creating lean muscle mass. Even eating less protein in the am is more beneficial than more protein at night, the data indicated. Here's why.

Proteins are essential for muscle building and healthy cell function

"Protein metabolism varies depending on the body's internal biological clock," according to researchers at Waseda University, a private research university outside of Tokyo. The consumption of protein at breakfast appears to work best to "increase muscle size and function in both mice and humans" they found. This specific area of study is called 'Chrononutrition,' since it explores the best times to consume food for optimal health.

So your usual breakfast choice of cereal, or a bagel, then lunch of a sandwich or wrap, or salad and then a dinner of high protein food is an upside-down approach to building healthy muscle, since your circadian rhythm is ready to build muscle early in the day, according to these scientists. It's optimal to eat more protein early in the day, at breakfast, an early snack, or for early lunch, while by the time dinner rolls around, it doesn't matter as much, since the muscles have had their fill of energy to repair and rebuild, making dinner a chance to "top off" the body's energy supplies before going to sleep and getting up to head to the gym the next day.

Here's the latest research on when to eat protein

The study at Waseda, led by Professor Shigenobu Shibata, set out to investigate the effect of your inner biological clock–or circadian rhythm–on food metabolism and found that protein digestion and absorption fluctuate throughout a normal 24 hour period. While prior studies have indicated that protein intake at breakfast and lunch promotes muscle growth, the exact reason and mechanism remained unknown.

In the study, laboratory mice were fed two meals per day containing either high protein (defined as 11.5 percent of the calories) or low protein (of 8.5 percent of the total calories). The mice that ate more protein at breakfast showed increased muscle growth, compared with the mice that ate higher levels of protein for dinner. Even mice fed a lower protein portion (of 8.5 percent) at breakfast had 17.5 percent more muscle growth than mice fed a higher ratio of protein (of 11.5 percent) at dinner. Additionally, the mice fed branched-chain amino acids, or BCAAs, at breakfast had even more muscle growth.

The researchers figured out that the driver of this was the animals' circadian clock, since they tried the exact same experiment on mice with no such body clock, and the protein intake in the morning did not lead to the same results. So our circadian rhythm is in control of our muscle growth and is the reason our muscles get stronger in response to what time we eat.

Eating more protein early in the day (at breakfast or lunchtime) could also help older people maintain muscle mass with advancing age–but most people eat proteins fairly unevenly throughout the day, another recent study has found.

"Protein-rich diet at an early phase of the daily active period, that is at breakfast, is important to maintain skeletal muscle health and enhance muscle volume and grip strength," said Professor Shibata, quoted in the academic journal Cell Reports.

Humans benefited from early protein intake as much as mice did

The same researchers then copied this experiment on 60 women aged 65 and over again proved that morning protein was optimal for muscle function, which they measured in grip strength. There is "a strong association" between grip strength and how much protein the women ate for breakfast, relative to their total protein consumption, the study found.

Professor Shibata explained that he hopes this work will have an impact on everyday dietary choices and timing, especially in the West and Asian countries, where people traditionally consume less protein at breakfast. "For humans, in general, protein intake at breakfast averages about 15 grams, which is less than what we consume at dinner, which is roughly 28 grams," he points out. "Our findings strongly support changing this norm and consuming more protein at breakfast or morning snacking time."

How much protein do you really need to build muscle?

One finding is that you don't need as much protein as you might think to build muscle, and in general we get more than we need in a day, according to studies. In fact, Americans get more of everything we need, and once your muscles and liver are full of energy, every extra calorie, whether it is protein or carbs, gets stored as fat, according to experts. One study found that excess protein has adverse effects on the body, including promoting weight gain.

The Academy of Nutrition and Dietetics recommends that you consume no more than 0.8 grams of protein per kilogram of your body weight or .35 grams per pound of body weight per day to maintain the body composition you have now. So a person that weighs 165 pounds (75 kgs) should consume about 60 grams of protein per day. Protein contains 4 calories per gram so that means eating 240 calories in protein a day. You can get this from your diet, without the need to supplement, which can create protein overload.

A recent study found that plant-based protein works just as well as whey does in building muscle. The reason people think that plant-based proteins are not as good as animal proteins is that they are not "complete" proteins, since they are missing one or more amino acid building blocks. The counterargument is that your body knows how to combine two incomplete proteins into a complete protein, as long as both proteins are eaten within a 24-hour window, according to research.

Here are the best high-protein foods to eat for breakfast or early snack

Check out six other surprising foods that can help you get more plant-based protein.

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