“We’re just passively sitting back and letting this inactive lifestyle become the accepted way.” Part of the problem is that Americans view physical activity as an "event" — one game of tennis or one trip to the gym — rather than "the manner in which one lives."
Cedric Bryant, chief exercise physiologist for the American Council on Exercise
If you are not exercising in order to burn up a few calories a day, why is it so important for an overall weight-control program? We have discussed some of the obvious reasons already (you feel better, you have more energy, etc.) but there is an even more important reason for sweating through a workout: exercise prevents muscle loss during long-term calorie deficits.(1) and allows for more effective maintenance of weight loss. (2,3,4). Allow me to explain.
While you are cutting back on the amount of calories you take in, the body automatically - from thousands of years of genetic programming, goes into "starvation mode." The reduction in food intake is interpreted in very familiar, simple terms by the body: "Famine! There is no food; we are starving; shut down everything that is not absolutely essential!" The body can adapt to almost anything and, over generations and generations, it knows exactly what to do when we didn't kill anything on the hunt or the crops didn't come in or our village was raided by bandits and there is no food for the winter. It goes into a metabolic shutdown. Your metabolic rate drops lower and lower as the days and weeks of reduced calorie intake ("dieting") continue.(5,6,7)
You have to remember, your body doesn't know you are cutting back on food intake voluntarily.It could not care less "why" you are doing this. All it knows is "we must be starving!" So, your body and your metabolism will fight you, tooth and nail, from losing weight. And, believe me, your body will always win. If you try to lose weight by simply cutting back on food intake you will fail. All the time, every time. Your body's metabolism is just too well-trained and too powerful. If you try to lose weight by dieting (starving) alone, you will eventually find yourself eating two crackers a day and you still won't be losing weight! Never underestimate the survival tools your body has been given.
Another thing that happens when you try to starve off weight (or "diet"): you start losing muscle tissue.(9) You see, when in starvation mode, the body starts scavenging for the energy it needs for survival. If you need more than you are eating, the body will get the energy from somewhere. Unfortunately for you, the body will not be picky. Instead of just burning up all those nice pounds of fat you have just lying around, doing nothing, the body will also burn up the other available tissue it has for energy. Specifically, muscle tissue.
The body's
metabolism is like a wildfire. It will burn anything it can in its
quest to generate energy to survive. It can't burn bone, so forget
that. It can't burn brain cells, so none there. It can't burn blood
cells; they are too valuable. But, it sure can burn up muscle. An
excellent protein source of energy - 4 calories per gram - just sitting
there for the taking. And the body does just that. In fact it makes
sense, at least to your genetic programming, to burn up muscle instead
of fat. Why? Because muscle is very metabolically
active. It requires a lot of energy just staying alive, even without
being used. Simply lying in bed, completely relaxed, your muscle tissue
burns about 30-50 calories per pound. If you have 75 pounds
of muscle tissue in your body, that is 3000 calories or so per day,
just to keep the tissue alive and doing nothing.
Now, what about fat tissue? Well, fat tissue is a very sluggish, metabolically "quiet" tissue. It only needs 3-5 calories per pound of fat per day to keep itself alive. It requires very little blood flow and does not generate any heat. So, if you were a highly trained, genetically engineered metabolic machine - the best machine ever created - and you were trying to last through starvation, ask your self which tissue would you most want to get rid of:
The most efficient machinery ever created, survivor of feasts and famines for thousands of years, makes a very reasonable choice. It burns up muscle tissue. True, it does burn fat also which, after all, is stored in the body for just this sort of "emergency." But, for someone who is voluntarily starving (or dieting), this is not a good thing. Why? For the same reasons we just mentioned. Muscle tissue is one of the most metabolically active tissue. It contributes a lion's share to what is called your basal metabolic rate, or BMR. Your BMR is the amount of calories your body burns up doing nothing. It is the calories burned up totally at rest and inactive. It is the energy used for such unconscious activities as breathing, maintaining body temperature at 98.6 degrees, breathing, replacing dying and dead cells throughout the body, etc. It can be calculated at this site. When we evaluate you at the Clinic, your body composition sheet with our goals for you (the one with your weight, height, and body fat/lean body mass calculations) has your BMR and projected daily calorie requirements printed out with it. Hopefully, you kept it and, if you did, you can just refer to it now.
Illnesses such as a fever, high levels of certain stress hormones (cortisol, thyroxin, insulin, etc.) in the body and either an increase or decrease in the environmental temperature will result in an increase in BMR. Fasting, starving (we call it dieting) or malnutrition all result in a lowering of BMR. This lowering of BMR can be one side effect of following a diet and nothing else. Solely dieting , i.e. reducing the amount of calories the body takes on, will not be as affective as dieting and increased exercise. The negative effect of dieting on BMR can be offset with a positive effect from increased exercise.But more on this later.
If you did take the time to visit the site above and calculate your basal metabolic rate (BMR), calculate using both the male and female gender. You will notice something extraordinary. The male - all things else being equal, namely: age, height, and age - always has a higher BMR than the female. Why do you think this is? Can you guess? It's for a very simple reason: all things being otherwise equal, a male has a higher muscle mass than a female and, thus, has a higher BMR. a number of other factors contribute to the BMR, but muscle mass is the larger factor that determines an individual's BMR.
Now that we know what our body needs, calorie-wise, for just living, we can get a better estimation of how many calories we actually do consume in an average day. Fortunately for us, we all burn more calories per day than our BMR. Even the most relaxed coach potato does some activity during the day and burns more calories per day just their calculated BMR. Once you have calculated your BMR, you need to do one of the following conversions to calculate how many calories you actually do burn in the course of a day.
Once you see how activity and muscle mass affect your daily calorie consumption, you will will start to see where we are headed with this discussion. Two things should be pretty clear at this point:
Now, think back to
all the "diets" (periods of starvation) you have forced on your poor
body over the years. Think about all the pounds you have lost and
regained, lost and regained, lost and regained. And think about this:
when you lose weight by just dieting, your body burns up about equal
parts muscle and fat. It consumes muscle for energy because muscle is
too metabolically active and is detrimental in times of starvation
(dieting). Fat because that is its purpose in the body. Fifty-fifty;
muscle and fat. So, on your last diet you lost 12 pounds.
Congratulations! You just lost 6 pounds of sluggish, inactive, ugly fat
tissue. On the other hand, you also just lost 6 pounds of energetic,
active, firm muscle tissue. You just lowered your BMR
significantly. Guess how easy it is going to be to regain those 12
pounds over the next few weeks and months?
Weight cycling, or "yo-yo dieting" has just this effect on the body. You starve (diet) and you lose weight. Fat and muscle.You think you have accomplished something very positive. You feel good about yourself but, eventually, your protective urges (hunger) regain control and you stop starving (dieting). Guess what you gain back when you, inevitably, regain the weight? Do you actually believe you gained back the same 50% muscle and 50% fat? Nope! Your body says "OK, this might happen again. So, we need to store up all the high-calorie (9 calories per gram, 3500 calories per pound), useless fat we can and no muscle! We don't need it and, besides, it is too expensive!" So, thousands of years of genetic selection causes you to regain all your lost weight as simply fat. Lose 6 pounds of muscle and 6 pounds of fat and regain 12 pounds of fat. Not a very good tradeoff, is it?
Unfortunately, that's the way of the human metabolism. How many times have you done the cycle? Up and down, starving (dieting) and refeeding? Weight loss and weight gain? For some of you, it may have only been once or twice. But, I am betting that for a large number of you it is more. Every time you do this cycling, your metabolism drops lower and lower as your muscle tissue gets less and less. And, if you haven't noticed, losing weight by just dieting (starving) gets harder and harder. If you have done this for 30 years, and I have patients who have, when you get in your 50s and 60s it gets to the point that it become virtually impossible to lose weight by dieting (starving). You eat two crackers a day and drink 2 gallons of water a day (call it the "cracker diet") and you don't lose weight! You sit and wonder why. The explanation should be pretty obvious by now. It's because a lifetime of starvation (dieting) has put your reduced your muscle mass, your metabolism in the toilet, and you now have the BMR of a common garden snail. Metaphorically speaking, of course.
Let's go back to our original question: If you are not exercising in order to burn up a few calories a day, why do it? You exercise not for the 300-400 calories per day you might burn but to protect your muscle mass.You might have heard the saying "Use it or lose weight" applied to many things, but it truly applies to your muscle tissue.If you are in starvation mode (dieting), your body is smart enough to shed the most demanding tissue in the body, muscle, especially if it is not being used. What happens if you are using your muscle tissue during a period of dieting (starvation)? Again, the body is able to adapt in the best interest of your survival. If you are using your muscles (exercising) during a period of dieting (starvation), the body will preserve muscle mass at all costs. It will shift its machinery toward selectively burning the one tissue it can truly afford to lose - fat - and protect the valuable muscle tissue from being cannibalized.
When you are starving (dieting) and exercising significantly, the ratio of tissue (weight) loss shifts. Instead of losng 50% muscle and 50% fat your body now will lose approximately 90% fat tissue and 10% muscle tissue. Lose 10 pounds, 9 pounds are fat, and only one pound is muscle. If - and it is a very big "if" - you are exercising. And not just taking a one mile stroll with friends at lunch. If you are sufficiently signalling the body that you need all your muscle tissue. It means using arms, legs, and torso significantly enough that the body senses these tissues are needed on a daily basis and must be protected. It is extremely important that your read and re-read these paragraphs, if necessary, until you understand the concept.
  |
Copyright © 2005
Albright Bariatric Clinic