your body shapes itself around what you do. If you sit in chairs all day and don't eat much, you'll look a certain way. If you eat a lot, move a lot, exercise a lot, you'll look a very different way. There's a number of "shapes" in between and beyond those positions but you get the idea. Do what you want to look.
This is the whole idea of fiber recruitment. If you use fibers of a specific type for a while, your body converts fibers of another kind to the one being utilized (through catabolism, recovery, and overcompensation).
If you run a lot, you'll develop a lot of type 1 fibers, which produce a thin, not-very-muscular looking body. Weight lifting with different quantities of time under the stress recruits different kinds of fibers as well (2a vs 2b). So, in essence you're right, but it's a lot more scientific than that.
Am I correct in understanding this discussion that my plan is NOT correct -- that I should expect to continue to eat 1350-1500 calories per day, and ultimately my metabolism will adjust to use these calories more efficiently so that I do not continue to lose?
It depends. You're already eating a very low amount each day, and eventually, yes, your body will catch on. It's just a question of which happens first, either you reach your goal or you stop losing at that caloric intake. This is also going to vary based on the macronutrients that you eat and the type of exercise you do.
Your metabolism is a moving target. Increasing your calories is the same as decreasing them. If I suddenly increase my calories by 2500, I'll put on weight but it won't be as rapid as you might think (excluding water weight). Various metabolic processes will occur, and my body will burn much more throughout the day.
HKaruga also makes a good point. The relationship between calories and weight is not as clear as once thought, and there are certainly a great many factors that affect such things.
Yeah, the medical and health-science community quite clearly knows what the relationship is. It's the common folk that misinterpret it. Physics is physics. If you burn 4000 calories, but consume 3500, there is a 500 calorie deficit. Your body will have to get those 500 calories from somewhere else. If it's strenuous activity causing the calorie consumption (IE, exercise), your body will catabolize muscle once glycogen is depleted as it's a faster energy source than body fat. Consumption of protein counteracts this and starts the recovery phase of the muscle. Assuming all other things equal (ignoring gluconeogenesis, etc), body fat would be the next thing to get burned. We all know that body fat provides 3500 calories per pound, and muscle provides around 600. Let's assume now that your body needs 1800 calories for some exercise you're doing (it's a stretch, but just work with the example at hand). 1800 calories coming from body fat will produce a .5 pound difference in weight, but coming from muscle it will produce a 3 pound difference in weight.
The math still works out, it's just the source of energy that's causing the difference in weight. More energy can be extracted per pound of fat. Despite what your scale may tell you, preserving the muscle is much more important in the long run. Body fat measurements are infinitely more important than scale readings.
The reason why people are disputing the "calories in vs calories out" fact (notice, fact, not theory) is because they're looking at the equation incorrectly
"Calories in" is the food you eat. Not much you can misunderstand there.
"Calories out" is where people mess things up. I'll try and explain how.
Someone mentioned the old atkins style diets and how some studies showed that people eating more calories lost more weight than high carbers eating less calories. That's the "calories out" portion of the equation at work.
Most people look at it too simplistically. The scenario below should be quite enlightening if you don't get it:
Imagine for a second that you cloned yourself. It's a perfect copy of you. Your metabolism is the same, your weight, height, fat percentage -- everything
Both of you eat 2000 calories today.
Both of you do the same activities and exercise, which causes an activity burn of 2500 calories per day.
This happens for 4 weeks.Both of you lose the same amount of weight, right?
Hang on to your seats....Not necessarily.
If the clone eats pure carbs and no protein, but you eat tons of protein and fat with barely any carbs, things are going to be very different, metabolically speaking.
The clone will lose muscle because the catabolism from the exercise and caloric deficit is not being counteracted with protein. A lot of weight
is lost, but most likely very little fat (unless you're both super obese).
You, however, (with your protein rich diet) experience a lot of weight loss too. The low carbing reduces glycogen replenishment, which in turn cuts a ton of water weight (glycogen stores water, roughly 2-3g per gram of glycogen). Your muscle is preserved. Assuming a low enough carb intake, ketosis occurs (metabolic process that happens to burn calories, adding to the "calories out" number). This means that energy is being drawn from fat while muscle is preserved (simplistic example, I know). Since your carbs are so low, gluconeogenesis kicks in, and the protein starts being used for glycogen creation. This is a metabolic process that also burns extra calories and adds to the "calories out".
I could keep going, but I think you get the point. The "calories out" aren't even close to the same, relatively speaking. Despite identical activity levels and caloric intakes, the macronutrients are determining which metabolic processes are active. Beyond that, while the clone is losing muscle (higher weight loss, but not the good kind
), you're losing water weight due to glycogen depletion. Furthermore, blood sugar levels that drop too low due to low carbing cause glucagon creation, which is actually catabolic (muscle burning) as well. I could go on for days with other factors that could change things.
In the end, who loses more weight? It's impossible to say, it depends on how much water weight you had to begin with, how insulin resistant you are, etc. Who loses more fat? The low carber.
This is a very simplistic example, but I'm trying to get a point across. "Calories out" is more than just what you do in a day. In fact, the "calories in" helps determine true "calories out". The math still works out and the total energy expenditure doesn't break the law of conservation of energy, but the scale will certainly tell you different results.
DISCLAIMER: I'm not endorsing low carb diets. This is an extreme example that tries to show different metabolic processes at work. The clone could just as easily be sparing muscle with a high carb diet. Also, he has more glycogen which fuels the work outs better. That's important. I'm not biased one way or another. Also, if any biology gurus want to dispute my facts, I don't care. Realize that I can't take into consideration every little detail. It's the big picture that counts.
So, the bottom line is, the relationship is very clear. Educated scientists know about it. Try explaining this to the laymen though. I just gave it my all, and I'm pretty sure I failed. Still, it's not some big mystery, there's just a lot of factors that people keep ignoring.
I hope that helps... someone.
If you think my post is too abrasive, harsh, or offensive, you're:
B) Too sensitive.
C) Not going to receive an apology for pointing it out.