Yesterday we looked at how the amount and timing of your protein intake can encourage muscle growth. However, one of the most common things I see as a sports nutritionist is athletes who think the ONLY thing that matters is protein. Far from it! The amount and type of food you eat can make or break your muscle building efforts, regardless of how much protein you’re getting.
The reason is that growing new muscle is an energetically expensive activity. Not only does it take a lot of energy to create new muscle, but it can be quite far down your body’s priority list. Your body tends to use extra calories to shore up the immune system, or increase reproduction first. So if you want to increase muscle mass, you need to eat more. In some cases, a lot more.
The first thing to look at is how many calories you need to maintain your weight. There are a variety of online calculators that will give you your Basal Metabolic Rate (BMR), which is the number of calories you burn at rest. You then take that number and multiply by your physical activity level (PAL) (see below). This gives you a rough guide to number of calories you need to eat to maintain your weight.
| Lifestyle | Example | PAL | |
| Extremely inactive | Hospital patients | 1.2 to 1.3 | |
| Sedentary | Office workers who drive to work and get no exercise | 1.4 to 1.5 | |
| Mildly active | Office workers who walk or cycle to work | 1.6 to 1.7 | |
| Moderately active | Construction worker or office worker who runs an hour a day | 1.7 to 2.0 | |
| Vigorously active | Agricultural worker or office worker swimming two hours a day | 2.0 to 2.4 | |
| Extremely active | Competitive cyclist or professional sports person | 2.5 + |
For example, when I enter my height, weight and age into these calculators, I get a BMR of 1325 Kcal per day (depending on which one I use). I spend most of my day sitting, but get between one and two hours of exercise, four or five days a week. This puts me in the Moderately active group, with a PAL of 1.7 to 2.0. So according to this, I need between 2250 and 2650 just to maintain my weight.
If you have a way to measure your body composition, you can use energy availability (as described in my post on the female athlete triad) to find the number of calories needed to maintain your weight. Energy availability is the amount of dietary energy remaining after exercise training. It is calculated as dietary energy intake minus exercise energy expenditure. As fat doesn’t use any calories and has no effect on how much you need to eat per day, it is standardised per kilogram of fat free mass. So in my case, if I weight 65Kg and am 26% fat, then my fat free mass is 48.1 Kg. If I eat 2000 kcal per day and burn 300 Kcal through exercise, then my energy availability is 35.3 kcal per Kg fat free mass per day (2000kcal minus 300kcal divided by 48.1 Kg).
Most athletes reach energy balance at 45 kcal/kg fat free mass/day. With 48.1 Kg of fat free mass, that would be 2165 Kcal per day for me. But I need to eat more than that to gain muscle mass: Generally speaking, at least 20% more. So in this example, I should be getting at least 2600 Kcal a day in order to gain weight. In practice, most athletes find they need to add about 500 kcal a day to their diet.
The catch is you cannot tell your body to use that extra energy only to build new muscle. It may very well decide to store some of those extra calories as fat. So tomorrow I’ll be looking at some tips and tricks you can use to encourage muscle building and discourage fat storage.