How should I change my diet when switching between exercises?

Question

I have been a runner/cyclist for the past six years. To help fuel my body I've been maintaining a high protein, high carb diet, gotten almost entirely from fruits, vegetables, and seafood.

Due to an injury, I won't be able to bike or run much for the next six months. Following a suggestion, I've decided to work on my upper body to pass the time. What I'm wondering is how should I alter my diet to help this new routine?

I imagine I should cut down on carbs and up the protein a little (fat as well?). I suppose I should also cut calories since I won't be burning as much. Is this accurate? I'm not looking to gain lots of mass, just build some long lean upper body muscle to help out when I get back to cycling and not gain fat.

Answer 1

I think you're approaching this the wrong way. Your questions are valid but you need to start from the bottom up, not vice versa.

Daily Calorie Needs

The first thing is determining your daily caloric needs. I wrote a quick post about this yesterday detailing what variables are involved and how to calculate your calorie needs. The short of it is: calculate your BMR, then use an activity multiplier to determine your Daily Caloric Expenditure.

Your calorie expenditure will vary day to day so it's a good idea to increase your caloric intake on training days and decrease it on rest days. This is also true if you do any type of unusual vigorous activity.

Calorie Goal

Once you know how many calories you need to maintain your weight, you have to decide whether you want to gain, maintain or lose weight. So if you want to gain weight and your maintenance is 2200, you can do a 500 calorie surplus and aim for 2700.

Your body is pretty good at regulating calories and will send you signals to tell you if you're undereating/overeating etc.

I like to do +500 calories on training days and -500 on off days. This is a composition shift diet, which means your weight stays about the same but your composition (Muscle/Fat ratio) improves.

Macro Split

As for the macro-split. A high carb diet is great if you are really active. But if you are just doing light/moderate lifting you can keep your carbs at around 30-40% of your total intake.

So your macro-split can be something like 40% carbs, 35% protein, 25% fat.

Meal Frequency

There is some differing opinions on the subject but from all the research I've done there is no significant relationship between meal frequency and your metabolism or calorie allocation.

I prefer to eat 4 meals a day since I eat every ~4 hours.