***The following Q & A is a continuation from my previous article, Training Your Metabolic Pathways (part 1).  Readers are encouraged to see the article (which explains how different energy systems work and how to train them) before reading this article.***

Okay, so what if your goal is to reduce your body fat?

Q: Why not train the first system, aerobic liposis, to ensure that all the calories being burned are coming from fat?

A: Because you have seemingly unlimited fat stores.  If you don’t deplete your glycogen stores, and happen to eat a little more, all of those extra calories will go into fat storage, since the glycogen tank is full.

Q: Why train so hard, in the glycolitic systems, all the time?

A: More bang for your buck.  In terms of calorie-burn per minute, the glycolitic systems win over the lipolitic system.  You don’t have to be in the gym nearly as long to burn calories.

Q: So what…?

A: If you are constantly depleting your glycogen fuel tank (which can hold 1,500 to 2,000 calories in the average person), you have a “free food window,” meaning… if you happen to overeat a few hundred calories of carbs, you can be guaranteed that they will simply go into glycogen stores, rather than fat storage.  This is how calorie deficits works.  As long as you keep your window “open,” it is difficult to gain weight from eating too much (unless your diet is very out of balance).

Q: Okay, so as long as I keep my glycolitic fuel tank half full…

A: You’ll be all right unless you’re bombing on pints of Haagen Dazs, blocks of cheese, and other high fat foods.  Your body only needs so much fat, and can only use so much as energy.  Eat too much, and it tends to go into storage.

Q: So if I train my aerobic glyocolitic system a lot and keep my “window open,” isn’t that enough?  Do I have to do all those nasty intervals and tough strength training sessions?

A: As I said before, more bang for your buck.  The higher the intensity, the more calories per minute you burn, and hence the wider that “window” is.  But, even better, if you train your body hard, you can increase the amount of glycogen that can be stored!

Q: Really?  How?

A:  Just as the body will make bigger muscles after a strength training session to be more prepared for the next time you place that kind of demand on them, the body will upgrade to a bigger fuel tank, in order to be more prepared for your habit of stepping on the gas all the time.  Conditioned endurance athletes can store up to twice the amount of glycogen compared to normal people (there is, admittedly, a genetic component to that as well).  So the more you condition your glycolitic systems, the more you keep your window open, and the bigger that window gets.

Q: Okay, so I train my aerobic glycolitic system a lot, and the idea of getting a bigger window (a bigger fuel tank) is nice, but I don’t worry that much about overeating.  So still, why bother with the anaerobic glycolitic system?  I can’t maintain my anaeobic intensity as long as  I can maintain my aerobic intensity anyway, so at the end of 40 minutes, I will have burned more calories than I will have burned in 15-20 minutes of anaerobic work.

A: Good question.  I have a two-part answer for you.  First, if you want to lower your body fat percentage, you can burn off some of your fat, you can put on more muscle, or you can do both.  Intervals aren’t the only anaerobic activity.  Resistance training also trains the glycolitic anaerobic system.   By adding more muscle, you lower your body fat percentage–but not necessarily your absolute body fat (amount of pinchable fat).

Q:  So I’ll still be fat, only with bigger muscles underneath?

A: If you eat too much, yes.  If you always eat enough to shut your glycogen “window” (fully replenish your stores) and something extra, your body will have no incentive to burn fat.  but remember, one pound of muscle, we have all heard, requires way more calories to maintain than one pound of fat.  Muscle requires protein, of course, and it stores glycogen, but during your day-to-day activity, your body will burn more fat to power itself.

Q: How much more?

A: A few tens of calories per pound.

Q: Is that it? A few tens of calories?

A: Well… yes.  But think of it this way, if you put on 5lbs of legitimate muscle over a few months and then just maintain it, that can be up to 150 extra calories burned per day.  That offsets fifteen pounds you could have potentially gained in a year.  Believe it or not, 10 lbs of weight gain per year can be quite normal for an adult.

Q: I guess that is a nice safety net.  But I want to drop my body fat now!

A: Then the most relevant thing to you is something commonly called “afterburn.”

Q: What’s that?

A: Afterburn is the amount of energy you use after your workout.  When you train at a very high intensity, your metabolism races.  When you’re done, it’s still going hard.  Imagine a car… you cruise in your car for a half hour, then park it in the garage.  It cools down eventually.  What if you red-lined that car until it overheated?  It would take much longer for the engine to cool down.  Same idea.   If you do some aerobic work at the gym, then hit the locker room, leave and head to a cafe to read, you click back into your day-to-day mode pretty easily.  But if you bust it at the gym, it takes much longer to relax, and maybe later in the day your muscles start humming.  Repair, repair, repair!  Replace, replace, replace.  These are highly metabolic activities.  You want to work hard at the gym often, to the point that your afterburn is apparent even to you.

Q: Okay, so every time I feel like hell after a workout, that’s a good thing?

A: That’s when the most weight loss and body re-composition happen, other than when you are sleeping.  The more you have to repair and replace all the time, the faster your body shape will change! And frankly, when you get off that treadmill or elliptical machine, you really haven’t done very much damage, even if you were pushing it.

Q: Riiight… I guess that makes sense.  So I just have to accept the fact that most of my workouts are going to be painful.  But who in their right mind wants to do something that hard all the time?

A: Pain and difficulty are relative feelings.  The more you challenge your body, the less it hurts in the long run, and the less difficult it is to confront.  Something that hurts and burns in one person feels completely manageable, if not comfortable, in another person.  Over time, as you become more fit, things hurt less.  That is fitness.

Q: But if things hurt less, then isn’t it harder to burn and break?  Won’t it be more difficult to challenge myself?

A: On the contrary, the more conditioned you become, the more you can take on.  The higher you raise your anaerobic-lactic acid threshold, the more reps you can squeeze out, the longer you can go, the more “damage” you can do.  Here’s an example.  You can work your anaerobic system by doing three sets of 12 dead lifts.  If you’ve been lifting for a while, you’re not likely to be super-sore afterwards.  Or, you can work your aerobic glycolitic system by doing over 100 dead lifts as fast as you can, at a lighter weight.  The end result is a bobble between aerobic and anaerobic, more reps, and hence more time your muscles are under strain.  You’re likely to be quite sore after that effort.

Q: Take-home lesson: always look for new ways to challenge myself.

A: One more thing.  Just as you train your energy systems to exercise, by exercising, you train your at-rest energy systems.  When you keep your glycogen stores perpetually half full, and your body is constantly trying to convert carbohydrates into glucose to re-fill them, the rest of your body relies more heavily on fat stores to power you through the day.  The more you exercise, the more fat you burn at home, period.

See you at the gym!