question about excercise

[ttt]

Hi, everyone
This is an article about the relationship between weight, food and exercise: Gary Taubes questions the relationship between physical activity and losing weight | Life and style | The Observer (The quotation below is from the end)

“The key is that among the many things regulated in this homeostatic system - along with blood pressure and blood sugar, body temperature, respiration etc - is the amount of fat we carry. From this biological or homeostatic perspective, lean people are not those who have the willpower to exercise more and eat less. They are people whose bodies are programmed to send the calories they consume to the muscles to be burned rather than to the fat tissue to be stored - the Lance Armstrongs of the world. The rest of us tend to go the other way, shunting off calories to fat tissue, where they accumulate to excess. This shunting of calories toward fat cells to be stored or toward the muscles to be burned is a phenomenon known as fuel partitioning.
The job of determining how fuels (glucose and fatty acids) will be used, whether we will store them as fat or burn them for energy, is carried out primarily by the hormone insulin in concert with an enzyme known technically as lipoprotein lipase - LPL, for short. (Sex hormones also interact with LPL, which is why men and women fatten differently.)
In the Eighties, biochemists and physiologists worked out how LPL responds to exercise. They found that during a workout, LPL activity increases in muscle tissue, and so our muscle cells suck up fatty acids to use for fuel. Then, when we're done exercising, LPL activity in the muscle tissue tapers off and LPL activity in our fat tissue spikes, pulling calories into fat cells. This works to return to the fat cells any fat they might have had to surrender - homeostasis, in other words. The more rigorous the exercise, and the more fat lost from our fat tissue, the greater the subsequent increase in LPL activity in the fat cells. Thus, post-workout, we get hungry: our fat tissue is devoting itself to restoring calories as fat, depriving other tissues and organs of the fuel they need and triggering a compensatory impulse to eat. The feeling of hunger is the brain's way of trying to satisfy the demands of the body. Just as sweating makes us thirsty, burning off calories makes us hungry.
If it's biology, and not a lack of willpower, that explains why exercise fails so many of us as a weight-loss tool, then we can still find reason for optimism. Since insulin is the primary hormone affecting the activity of LPL on our cells, it's not surprising that insulin is the primary regulator of how fat we get. 'Fat is mobilised [from fat tissue] when insulin secretion diminishes,' the American Medical Association Council on Foods and Nutrition explained back in 1974, before this fact, too, was deemed irrelevant to the question of why we gain weight or the means to lose it. Because insulin determines fat accumulation, it's quite possible that we get fat not because we eat too much or exercise too little, but because we secrete too much insulin or because our insulin levels remain elevated far longer than might be ideal.”





I wonder if that means that a person who excercises and then doesn’t eat for some time he will burn more calories? Has anyone tried something like that? If this information is true than eating after excercise would not cause weight loss, because the cells take back the fat they have lost.

[Brutha]

The process that regulate those processes are more complicated than one lipase doing something.

Mainstream nutritionists don't even believe that excercise will always produce weightloss.
They believe that it will if you weight to much.
No doctors thinks that undersweight people shouldn't excercise.

The idea is basically that the fact that you excercise will affect your hormons in way that that activates the inbuild regulatory mechanisms that regulate wight.
Not excercising at all is highly unnatural so your body isn't really work well when there's no excercise.

[TimG]

hi ttt

There are some people who have medical conditions that prevent them losing weight, a doctor is the right person to diagnose it.

After ruling out such conditions, weight loss is a simple formula: You must expend slightly more calories than you consume.

Because of this, I don't believe the article you quoted is true. For example, the author asks some questions that are easily answered:

If lean people are more physically active than fat people (who says?) does that mean that working out will make a fat person lean?
yes - IF they expend more calories than they consume!
Does it mean that sitting around will make a lean person fat?
yes - IF they consume more calories than they expend!
How about a mathematical variation on these questions? Let's say we go to the gym and burn off 3,500 calories every week - that's 700 calories a session, five times a week. Since a pound of fat is equivalent to 3,500 calories, does that mean we'll be a pound slimmer for every week we exercise?
yes - IF you expend 3,500 calories more than you consume in the week
And will we continue to slim down at this pace for as long as we continue to exercise?
No - IF you consume more calories than you expend, and even if you don't you will eventually reach the point where your bodyfat percentage has reached it's healthy limits.

I could go on, but the author also says the ACSM can't "prove it". Why then do they recommend exercise?

From the American College of Sports Medicine website:

Metabolism and Weight
Loss
A more viable and realistic solution is to
help people understand metabolism’s role in
weight loss. Metabolism, by definition, is
the total of all cellular reactions that occur in
the body. Basically, metabolism involves two
processes: anabolism and catabolism.
Simply stated, anabolic reactions result in
the building of cellular structures and the
storing of energy. For example, if you lift
weights regularly, a portion of the protein
that you ingest is used to build muscle tissue
via anabolic reactions. On the other hand,
catabolic reactions refer to the breaking
down of molecules for energy. For example,
if you exercise regularly and eat less than
your body needs, your body will break
down fat stores for energy via catabolic reactions.
The key to weight loss is to speed up metabolism
by increasing both anabolic and catabolic
reactions. Simply stated, through exercise
and dietary modification, both anabolic
and catabolic reactions can be increased,
thereby increasing your likelihood of achieving
a healthy body weight and optimal body
composition.
To fully grasp how to increase metabolism,
we must further explore catabolism. Energy
is stored in food. For instance, one gram of
carbohydrate and one gram of protein each
contain four calories of energy, whereas one
gram of fat contains nine calories of energy.
When any of these are consumed, an anabolic
or catabolic reaction occurs. If you
exercise regularly and do not eat excessively,
then the fats and carbohydrates that you eat
undergo catabolic reactions (keep in mind
that under these conditions, proteins undergo
anabolic reactions and are used to maintain
or build muscle tissue). These fats and
carbohydrates are broken down and their
energy is used to: (1) carry out life’s necessary
functions, such as breathing; (2) perform
daily tasks, such as combing hair; (3)
digest food; and (4) exercise. It’s been estimated
that active females and males require
2,200 and 2,900 calories per day, respectively,
to satisfy the catabolic demands placed on
the body. Based on these estimates, for
example, an active female who consumes
about 2,200 calories per day will more than
likely maintain her weight. On the other
hand, if she is not physically active and eats
too many fats, proteins and/or carbohydrates,
then her body will store any unused
energy as fat. If this is getting a little too
overwhelming, just remember this:
If you consistently take in:
• More calories than you need, then your
body will store the extra calories as fat.
• The same amount of calories as your body
needs, then you will not gain or lose
weight.
• Less calories than your body needs, then
you will lose weight.
To achieve a healthy body weight and optimal
body composition, the key is to maximize
your metabolism and reduce your
caloric intake. To increase your metabolism,
you should: (1) increase your muscle mass
by performing resistance exercise two to
three days per week (e.g., working out with
elastic bands, weights, stability balls, body
bars, etc.); (2) work up to at least 200 minutes
of aerobic exercise per week (e.g., walking,
jogging, bicycling, step aerobics, etc.;
and (3) eat a low- (but not too low) calorie
diet. Eating less than 1,200 calories per day
has been shown to decrease your metabolism.
Although everyone is different, to lose
about one to two pounds per week, active
men should eat about 1,800 calories per day
and active women should eat about 1,500
calories per day. Remember, there is no miracle
pill or other “quick-fix” solution for
jump-starting a person’s metabolism. One
who is willing to make simple lifestyle
changes and be consistent in their application
will reap the future benefits of a healthy
body weight and composition.

The article you quoted is bunk!