Nutrition thoughts I wrote up a while ago

[flexagon]

I've been thinking a lot lately about calorie deficits and weight loss.

I was thinking how there's a total contradiction between these two statements:

1) you get 9 calories from a gram of fat, 4 from a gram of protein and 4 from a gram of carbohydrates

2) the body uses protein and lipids to build structural elements (unsaturated fatty acids make great cell walls, doncha know).

So unless I'm reading something wrong, carbs are actually the only thing that's always converted to energy or stored as fat! (By energy, I mean ATP and CP, the stuff that moves muscles). So what's correct is that the body can get that many calories out of the stuff you put in your mouth, IF that stuff is used for energy, which not all of it is. Increase exercise level and I bet you anything the amount of material needed for structural repairs/building goes up... and I bet that's a lot of what "base metabolism" is.

Thoughts?

Comments

[bluechromis.livejournal.com]

So what you're saying is that since some of the macro molecules you're taking in are used for structural things as opposed to energy, they therefore don't "count" in the calories taken in vs. burned equation? I would agree with that, calories in vs. calories out seems simplistic.

Part of the problem is that it's nearly impossible to estimate accurately how much someone "burns" during a weight-lifting session, so separating whether you would just say, for example, "x amount of protein calories don't count because they're being used structurally", vs. "I'm burning x amount of calories from weight lifting" is very difficult. All macromolecules are broken down and at least partially used in energy pathways. They're also all used in structural pathways. Carbs are obviously most directly used in energy pathways, and proteins are used most directly in structural, but they're all broken down completely before they do anything at all, and that takes energy in and of itself.

At the end of the day, for me personally, it's an academic question, because my personal experience is that a moderate calorie deficit is required for fat loss. Playing with the macromolecule percentages doesn't help, weight-lifting doesn't help. The only thing that gets results is eating less and burning more through aerobic exercise. Presumably if I were doing a combined strength/endurance weights-only program that would work too, and of course low-carb "works", at least in the short term, but eating less and doing more cardio is the most effective combination. Everyone's metabolism is different of course, and everyone's starting point is different. I have a lot of muscle to begin with, so I'm sure that's part of why lifting has never made a huge difference in my apparent calories burned number.

[flexagon]

So what you're saying is that since some of the macro molecules you're taking in are used for structural things as opposed to energy, they therefore don't "count" in the calories taken in vs. burned equation?

Yes, or so it seems to me. I know the macromolecules all get broken down to some extent, but in the end, the stuff used for structure isn't used for energy; and so it's interesting that I've never read anything about, say, how many calories' worth is actually used for structure. Maybe nobody knows.

Part of the problem is that it's nearly impossible to estimate accurately how much someone "burns" during a weight-lifting session

And what's burned during is only part of the energy burned because of the exercise total. I'm sure you know about EPOC (excess post-exercise oxygen consumption), a fancy way of saying that the body has to replenish the stores of energy in and near the muscles after a workout. So, yeah, nearly impossible.

my personal experience is that a moderate calorie deficit is required for fat loss

So says the book (thanks for the bomb calorimiter nugget though, it didn't say that). I have never gone through the effort of actually counting calories, so I have no particular personal experience. I've found weight lifting to be the only thing that changes the shape of my body. But I wasn't thinking of this post in terms of what to do, precisely... just musing on this, and on the nature of base metabolism. Yeah it's just academic... but interesting. :)

[bluechromis.livejournal.com]

I can totally see why weight lifting is what's changed your body shape. I think to at least some extent that's true of everyone, but a lot of people can't see their real body shape changing until they've lost the overlying fat, and since you didn't have much fat to lose in the first place, lifting would be the most dramatic thing. I'm actually doing an experiment right now since I want to focus on running anyway to see if long distance running reshapes my thighs to be longer and leaner, not doing any lower body strength other than core.

I am sure studies have been done in non-animal models to track a macromolecule from intake to cellular use, but I don't know how they'd add that information to the energy equation. There are so many variables from one moment to the next.