If you're trying to maintain muscle strength, you're probably no stranger to protein. More protein means stronger muscles, right? Makes sense since protein-rich foods such as meat, poultry and fish supply amino acids, the building blocks of muscle tissue. While it's true that how much protein you eat is important for muscle growth (to a limit), what seems to matter more is how you distribute your protein intake throughout the day.
According to researchers from the University of Texas Medical Branch in Galveston, you'll build more muscle if you evenly spread your protein intake over three meals rather than skewing your intake toward the evening meal. In other words, if your usual diet includes little or no protein at breakfast (e.g. cereal and milk, toast and jam), a bit more at lunch (e.g. a sandwich) and a large serving of meat, poultry or fish at dinner, you could be doing your muscles – and your health – a disservice.
For the study, published in the June issue of The Journal of Nutrition, healthy 37-year-olds followed two similar diets that differed in protein distribution. Both diets provided 90 grams of high-quality animal and plant proteins each day (more than the official recommended intake). One diet contained 30 grams of protein at each meal, while the other had 10 grams at breakfast, 15 grams at lunch and 65 grams at dinner.
Blood samples and thigh-muscle biopsies were used to determine the participants' muscle protein synthesis rates over a 24-hour period. The balance between muscle synthesis – making new protein – and muscle breakdown, which occurs to remove damaged proteins, is vital to maintaining overall muscle mass.
The most effective diet for muscle health proved to be the one that delivered 30 grams of protein per meal. Over the course of 24 hours, muscle synthesis was 25 per cent higher when protein was evenly distributed between meals compared to when most of it was eaten at dinner.
If you're hitting the gym in an effort to gain muscle, eating protein-centred meals could give you an edge. These findings are most relevant, however, for those of us trying to slow down muscle loss that occurs naturally as we age. If you're not already thinking about preserving your muscle mass, you should be.
In our 30s we begin to lose muscle mass and function, a process called age-related sarcopenia. If you're sedentary, it's possible to lose as much as 5 per cent of muscle tissue every decade after age 30. Even if you work out regularly, you'll still lose some muscle.
Sarcopenia does more than slow your resting metabolism, making it easier to gain weight. (Your resting metabolism is largely determined by how much muscle you have; it's the number of calories required to keep your heart beating, your lungs breathing and your brain and liver functioning at complete rest.) Sarcopenia also reduces muscle strength and mobility. And it predisposes older men and women to falls and bone fractures that can substantially affect quality of life and be potentially life-threatening.
How much protein you need for optimal muscle health is under debate. There's plenty of evidence that the official Recommended Dietary Allowance of 0.8 grams of protein per kilogram of body weight – an amount deemed adequate to prevent protein deficiency – isn't enough if you're 50 or older. Many experts advise that adults 65-plus get 1.0 to 1.2 g protein per kilogram of body weight each day to maintain muscle mass and function. For a 170 pound [77 kg] male, that's equivalent to 77 to 92 g of protein each day.
There's no advantage to piling up protein at one meal since there's a limit to the rate at which protein can be synthesized into muscle. An earlier study by the same researchers showed that eating 12 ounces of beef (84 g protein) had no greater effect on muscle protein synthesis than a smaller four-ounce serving (34 g protein).
The ability of protein to simulate muscle growth and repair can be influenced by exercise, health status, age and body composition. Even so, these new findings add to growing evidence that a meal containing 30 g of protein is the best recipe for maximally stimulating muscle protein synthesis in healthy adults.
If you don't eat enough protein for efficient muscle building during the day and eat more than your muscles can use in the evening, rebalance your meals. Doing so can optimize your muscle health, not to mention control your calorie intake later in the day.
Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto. She can be seen every Thursday at noon on CTV News Channel's Direct; lesliebeck.com.
Leslie Beck