RE: Can I ask one more question......?
The texts are Understanding Nutrition, Essentials of Exercise Physiology, Nutrition for Serious Athletes, and Sport Nutrition for Health and Performance.
This may get long, so I apologize in advance--but if you can bear with me, it may answer some questions. First of all, let me say that the more I learn, the more I realize there is to know--and what there is to know is enough to make your head spin! But in order to catch the more complex stuff and fine points, it is necessary to really understand the basics, which in and of themselves can be challenging enough. I also really appreciate you all allowing me to share the info with you--it is really good for my brain to have to write and explain this stuff--every time I do, something else goes "click".
Three key points to keep in mind: 1) Calories in vs calories out is the equation that determines whether a person gains, loses or maintains weight--but timing and source of nutrients determines whether the weight lost is from water, stored glycogen, lean muscle mass or fat stores. 2) If glycogen/blood glucose levels fall below a certain point, the body HAS to make more out of fat and protein--problem is that ~85% of what is used to make glucose comes from PROTEIN stores, compromising lean muscle. 3) Fat can only be used as a source of energy for exercise when there is adequate glycogen/glucose and oxygen available.
Keeping these three key points in mind, and realizing that blood glucose/glycogen levels are low first thing in the morning, you can see why it is critical to replenish before exercise if your goal is to spare lean muscle mass and to maximize your fat utilization during aerobic activity. It doesn't take much--just enough calories to prime the pump and get you to the point in the aerobic exercise session where fat can really kick in as an energy source. Even 100 calories' worth of carbs will make a difference if you are a person who can't stomach much before a morning workout. If you are going to be doing strength training, you will most likely need even more because strength training requires glucose almost exclusively to fuel the workout.
And, for people who work out later in the day, you still aren't off the hook as far as eating breakfast goes. You, too, need to start the day with a little carb boost to get blood sugar levels up for the activities of the day. Even without a workout, your body still has to have glucose to go through its normal activities and if you are low on it, it has to be made--again, with ~85% protein, so not eating is a good way to guarantee loss of muscle mass. You also need to make sure you have something to fuel your workout whenever you are going to do it--and it needs to be within a couple of hours of your exercise session.
When it comes to post exercise refueling, if the workout was cardio in nature, the refueling should be primarily carbs. The reason for making them simple carbs is that the window of opportunity to maximize glycogen storage after exercise is fairly narrow and simple carbs will be digested and absorbed more quickly that will complex carbs. Again, it doesn't take a huge amount of calories to do the trick.
On the other hand, if the workout was resistance training in nature, the snack needs to include a portion of your daily protein intake to provide the amino acids necessary for the body to rebuild the muscle tissue breakdowns that occur. I'm not talking about very low level resistance training--I'm talking about the intensity of training that really challenges the muscle. Does the protein have to come from supplements? Absolutely not. You can eat regular foods that are good sources of protein.
Not feeling hungry post-workout isn't a good gauge of whether you need refueling. The circulating catecholamines (like norepinepherine) that increase with exercise will supress the appetite for a period of time after exercise. And, the more intensely you exercised, the longer this effect tends to last. The amount of refueling does depend on the amount of calories burned during the session.
Now, I have an idea of what the next questions will be--how much of each nutrient do I eat and when do I eat them? Good questions--and the answers could get a little complex, but this is the easiest way to look at it. There is a reason that the reputable dietitians and exercise scientists recommend multiple small meals vs three big ones. They keep your blood sugar level, which prevents loss of lean muscle mass, fatigue, ravenous hunger and out of control cravings for simple carbs. So, what I recommend is to figure your total daily caloric intake based on your goals (gain, lose or maintain weight), then calculate the number of calories from carbs, protein and fat you should take in each day.
Here's where you get to play--staying within the total caloric range you need to be in based on your goals, allot your pre- and post-workout snacks according to your needs for the type of workouts you'll be doing. It's just a matter of figuring in your workout appropriate snacks with the rest of your calories in calculating your total daily intake.
Hope this book of a post helps clear things up. I have another biggie on muscle mass development coming up!
Maribeth
The texts are Understanding Nutrition, Essentials of Exercise Physiology, Nutrition for Serious Athletes, and Sport Nutrition for Health and Performance.
This may get long, so I apologize in advance--but if you can bear with me, it may answer some questions. First of all, let me say that the more I learn, the more I realize there is to know--and what there is to know is enough to make your head spin! But in order to catch the more complex stuff and fine points, it is necessary to really understand the basics, which in and of themselves can be challenging enough. I also really appreciate you all allowing me to share the info with you--it is really good for my brain to have to write and explain this stuff--every time I do, something else goes "click".
Three key points to keep in mind: 1) Calories in vs calories out is the equation that determines whether a person gains, loses or maintains weight--but timing and source of nutrients determines whether the weight lost is from water, stored glycogen, lean muscle mass or fat stores. 2) If glycogen/blood glucose levels fall below a certain point, the body HAS to make more out of fat and protein--problem is that ~85% of what is used to make glucose comes from PROTEIN stores, compromising lean muscle. 3) Fat can only be used as a source of energy for exercise when there is adequate glycogen/glucose and oxygen available.
Keeping these three key points in mind, and realizing that blood glucose/glycogen levels are low first thing in the morning, you can see why it is critical to replenish before exercise if your goal is to spare lean muscle mass and to maximize your fat utilization during aerobic activity. It doesn't take much--just enough calories to prime the pump and get you to the point in the aerobic exercise session where fat can really kick in as an energy source. Even 100 calories' worth of carbs will make a difference if you are a person who can't stomach much before a morning workout. If you are going to be doing strength training, you will most likely need even more because strength training requires glucose almost exclusively to fuel the workout.
And, for people who work out later in the day, you still aren't off the hook as far as eating breakfast goes. You, too, need to start the day with a little carb boost to get blood sugar levels up for the activities of the day. Even without a workout, your body still has to have glucose to go through its normal activities and if you are low on it, it has to be made--again, with ~85% protein, so not eating is a good way to guarantee loss of muscle mass. You also need to make sure you have something to fuel your workout whenever you are going to do it--and it needs to be within a couple of hours of your exercise session.
When it comes to post exercise refueling, if the workout was cardio in nature, the refueling should be primarily carbs. The reason for making them simple carbs is that the window of opportunity to maximize glycogen storage after exercise is fairly narrow and simple carbs will be digested and absorbed more quickly that will complex carbs. Again, it doesn't take a huge amount of calories to do the trick.
On the other hand, if the workout was resistance training in nature, the snack needs to include a portion of your daily protein intake to provide the amino acids necessary for the body to rebuild the muscle tissue breakdowns that occur. I'm not talking about very low level resistance training--I'm talking about the intensity of training that really challenges the muscle. Does the protein have to come from supplements? Absolutely not. You can eat regular foods that are good sources of protein.
Not feeling hungry post-workout isn't a good gauge of whether you need refueling. The circulating catecholamines (like norepinepherine) that increase with exercise will supress the appetite for a period of time after exercise. And, the more intensely you exercised, the longer this effect tends to last. The amount of refueling does depend on the amount of calories burned during the session.
Now, I have an idea of what the next questions will be--how much of each nutrient do I eat and when do I eat them? Good questions--and the answers could get a little complex, but this is the easiest way to look at it. There is a reason that the reputable dietitians and exercise scientists recommend multiple small meals vs three big ones. They keep your blood sugar level, which prevents loss of lean muscle mass, fatigue, ravenous hunger and out of control cravings for simple carbs. So, what I recommend is to figure your total daily caloric intake based on your goals (gain, lose or maintain weight), then calculate the number of calories from carbs, protein and fat you should take in each day.
Here's where you get to play--staying within the total caloric range you need to be in based on your goals, allot your pre- and post-workout snacks according to your needs for the type of workouts you'll be doing. It's just a matter of figuring in your workout appropriate snacks with the rest of your calories in calculating your total daily intake.
Hope this book of a post helps clear things up. I have another biggie on muscle mass development coming up!
Maribeth