Studying the human body isn't rocket science – in some cases, it's much harder.
"I tell my grad students that we can put a man on the moon, but we still can't come to a consensus on how much protein to give him here on earth," says Dr. Rajavel Elango, a researcher at the University of British Columbia's School of Population and Public Health.
Elango and his colleagues are using a new measurement technique to rewrite assumptions about how much protein you need at different stages of life. But just getting the right amount isn't enough: There's a limit to how much protein your body can use at once, so to maximize muscle-building you need to spread your intake throughout the day – and for most Canadians, that means ramping up the protein content at breakfast and lunch.
Your muscles are constantly being broken down and rebuilt at a rate of about 1 to 2 per cent per day, which means that you get a completely new set of muscles every two or three months. The protein you eat provides the basic building blocks – amino acids – needed to keep up with this constant rebuilding.
To figure out how much you need, scientists have traditionally tracked protein's nitrogen content as it's ingested and excreted by volunteers – a cumbersome process prone to errors, Elango says.
Instead, he and colleagues in Toronto, Edmonton and elsewhere have developed an alternate method that involves tagging amino acids with a special carbon isotope tracer whose progress through the body can be precisely monitored. Their results suggest that current protein guidelines for healthy adults are underestimated by about 30 per cent.
Since the new test is faster and less invasive than the old one, it can also be used to check requirements in vulnerable populations like children, pregnant women and older adults. In each of these examples, the new results suggest that current guidelines are too low, by as much as 70 per cent in the case of children between the ages of 6 and 10.
In Canada, the vast majority of people easily consume enough protein during the day – the problem is how it's distributed. Whenever you eat protein, your body responds by firing up its anabolic (muscle-building) processes. The more protein you eat, the more muscle protein you synthesize – up to a point. Research by McMaster University's Dr. Stuart Phillips and others has found that if you eat more than 20 to 30 grams of protein at a time, you don't get any further anabolic boost. Any extra protein is simply burned for energy; unlike carbohydrate or fat, you can't save it for later.
Unfortunately, typical Canadian dietary patterns involve food choices and meal sizes that provide relatively small doses of 10 to 15 grams of protein at breakfast and lunch, and then a mammoth 65-gram wallop of protein at dinner. The daily total of 90 grams is great, but since more than half of the dinner protein goes to waste, the usable amount of protein is actually below the optimal amount for muscle maintenance.
"You can overconsume protein to your heart's content, but unless you distribute it appropriately, you can still fall well below the body's needs," says Dr. Douglas Paddon-Jones, a professor of nutrition and metabolism at the University of Texas. Instead, Paddon-Jones recommends distributing protein more equally throughout the day, aiming for three meals each with 30 grams of protein – by including eggs and high-protein dairy options like Greek yogurt at breakfast, for example.
Athletes who are trying to build muscle (or simply help their muscles recover from arduous workouts) can push that approach even further. Phillips and his colleagues recently tested three different ways of taking in 80 grams of protein in one day: eight equally spaced doses of 10 grams; four doses of 20 grams; or two doses of 40 grams. The intermediate option produced the greatest overall muscle protein boost, so Phillips suggests that athletes should aim for four daily meals each with at least 20 grams of protein. And there's one final option to boost protein synthesis at the end of the day.
"When you couldn't sleep, what did your grandmother tell you?" Phillips asks. "Drink a warm glass of milk."
Indeed, a study published last year by researchers in the Netherlands showed that a dose of protein immediately before bed kept the body in an anabolic state overnight, boosting overall protein synthesis rates by 22 per cent.
Of course, you don't build muscle just by eating. The anabolic effects of eating protein are doubled if combined with exercise, which is one of the reasons athletes are encouraged to refuel immediately after working out. But if you follow the advice to spread out your protein intake, then you don't need to worry about the precise timing, according to Paddon-Jones.
"You don't want to be the tea-and-toast breakfast eater who exercises and then doesn't get any protein until the afternoon," he says. "But if you distribute protein throughout the day, it doesn't really matter when you exercise."
Alex Hutchinson blogs about exercise research at sweatscience.runnersworld.com.