Originally posted by mingster
there's so much conflicting info out there surrounding this issue. what to eat before and after your workout and when. it's difficult to know what right and what's wrong. i've heard before that you should eat protein immediately after your workout.
what do you say about the conflicting info? what's your advice on how to take it all? i'm assuming most of these "tips" are based on scientific fact, so how come they are often so different?
Practically speaking, I'd say that what you eat beforehand really can be up to personal preference. Me personally, I train better on a somewhat empty stomach. If I do eat anything, it'll be a small amount of complex carbs (i.e. 30-40 grams worth). For fat loss purposes there is an advantage to working on a slightly empty stomach in that lower blood sugar levels means that your body has to resort to existing energy stores (i.e. glycogen in muscle or fat tissue) in order to meet energy demands.
Postworkout nutrition I think is far more important an issue because the body is biochemically primed in a lot of ways. Primed to store carbohydrate more in muscle tissue and not in fat, primed to repair and growth muscle tissue.
Regarding the conflicting advice, I think it's important to consider the source. Fitness articles are often written by people with no real credentials and very rarely with substantiated by research. Take protein intake for example. Peter Lemon's work in the field is the bottom line, he's covered just about every aspect of it, there is not much mystery left on that issue. But talk to any meathead bodybuilder and crack open any muscle magazine and the range of reccomendations varies wildly.
The research on the subject is pretty clear because training physiologists know how important the post workout meal is for different purposes. I think the facts speak from themselves on this issue with regard to the necessity of water, carbohydrate (both simple and complex), protein. New articles in the fitness industry for example do not override long standing principles of human physiology.
To elaborate :
If you eat protein directly after your workout, it won't necessarily be bad, because again your body is primed to use that protein effectively.
However, the body does follow certain metabolic preferences. For example, when it has glucose available in the bloodstream, it will tend not to use existing fat stores. From a common sense standpoint, this makes sense. There's fuel in the blood, so why bother chewing into fat stores, which the body keeps on hand to prevent death and starvation.
More common sense proof for the order of priority in the body can come from the common knowledge that you can go without food for a few weeks but will die of dehydration within a matter of days. So hydration needs take precedent over energy needs, and energy needs take precedent over muscle growth needs.
The biochemical basis for this is that protein can be broken down into glucose when the body is in desperate need (this is one of the reasons why people who are in prolonged states of starvation have their muscle tissue waste away).
The body breaks down the muscle tissue not just because it means the body now has less shit to keep alive and thus improves survival, but because the can convert amino acids to glucose when there is no glucose provided through dietary carbohydrate. Energy can thus be derived from existing muscle.
This all taken into account, if your body is seeking carbohydrates but isn't getting them after a workout, it can catabolize incoming protein for the carbohydrate it needs. Hormones like cortisol run high during and after a workout - it's one of the chief chemicals that can help facilitate this protein -> glucose process.