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Old 12-27-2009, 11:11 PM   #1
Greg Condon
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Nutrition Guru, Total Calories In vs Weight Gain and Loss Question.

I have been pondering this for a while now. I see these shows about people that eat 30000+ cals a day and are 900lbs. well 33k is approx 10+ pounds a day, 3650lbs gained in one year.

I hear this formula that says eat LESS calories then your body is burning to loose weight

I also know there are days that I have eated 10k or more in calories. Hence why i am 330lbs. But I don't always gain the same amount of weight that I eat less what i approx burn every day.

Does every ounce of food really require the "set" amount of calories it says it is to "eliminate" (for lack of a better word) itself from your body? so if cheat one day, does every calorie always tack itself onto my body in some way? or does my digestive system push some of those "calories" out without processing them?

and I don't want to sound sick, but sometimes if you look you can see unprocessed food in your elimination....corn...beans etc. So did my body just not process that because it didn't have time to before it moved on out of the stomach? does the process of "burning" calories happen all thru the system? how does that work.

so i guess my basic question is...does your body always have to process every calorie that enters the body? does it just ramp up the process a bit if you overload it and then just tack on the extra if it can't handle it all?
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Old 12-28-2009, 01:02 AM   #2
Katherine Derbyshire
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Re: Nutrition Guru, Total Calories In vs Weight Gain and Loss Question.

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Originally Posted by Greg Condon View Post
so i guess my basic question is...does your body always have to process every calorie that enters the body? does it just ramp up the process a bit if you overload it and then just tack on the extra if it can't handle it all?
This question is discussed at great length elsewhere in this board. You might try a search. You might also try a basic biology text, which will explain digestion, cell metabolism, and related topics.

Very briefly, the body can do one of three things with an incoming calorie:
* excrete it. This is what happens with indigestible fiber: it passes through the intestine and out the other end without being absorbed.
* burn it to power the body's various systems
* store it. Long term calorie storage is in the form of fat. But the body also stores glycogen, which is what fuels short-term energy expenditures. If the glycogen stores are depleted, the body can replenish them from food or by drawing on its fat reserves.

The balance among these processes depends on diet, activity level, basal metabolism, and a variety of other things. Unless you live inside a calorimeter, it's very difficult to determine exactly how many calories you are burning at any given time. Unless you live on sugar, whey protein, and lard, it's also difficult to determine exactly how many calories your body will get from a given meal.

So yes, the body must do *something* with every gram of food it consumes. But you can't know your energy intake *or* your energy expenditure precisely enough to say exactly what is happening to a particular amount of food. It's certainly not "safe" to overeat on the assumption that your metabolism will ramp up to burn the excess. (While some people do burn a lot of calories by fidgeting and pacing, someone who is already overweight probably isn't one of those people. This is also why it's hard to lose weight through exercise: the body ramps up your appetite to replace the calories you burned.)

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Old 12-28-2009, 01:27 AM   #3
Mauricio Leal
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Re: Nutrition Guru, Total Calories In vs Weight Gain and Loss Question.

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Originally Posted by Greg Condon View Post
so i guess my basic question is...does your body always have to process every calorie that enters the body? does it just ramp up the process a bit if you overload it and then just tack on the extra if it can't handle it all?
I don't know about people 900 lb+ and consuming 30,000 calories/day...eating that much food in a day would be a herculean task in chewing and swallowing alone.

As for your body processing food calories, well I just happened to be reviewing my thermodynamics textbook yesterday:

Quote:
...the average energy contents of the three basic food groups are determined by bomb calorimeter measurements to be 18.0 MJ/kg (4.3 Calories/g) for carbohydrates, 22.2 MJ/kg (5.3 Calories/g) for proteins, and 39.8 MJ/kg (9.5 Calories/g) for fats. These food groups are not entirely metabolized in the human body, however. The fraction of metabolized energy contents are 95.5 percent for carbohydrates, 77.5 percent for proteins, and 97.7 percent for fats. That is, the fats we eat are almost entirely metabolized in the body but close to one quarter of the protein we eat is discarded from the body unburned. This corresponds to 4.1 Calories/g for proteins and carbohydrates and 9.3 Calories/g for fat commonly seen in nutrition books and on food labels. The energy contents of the foods we normally eat are much lower than the values above because of the large water content (water adds bulk to the food but it cannot be metabolized or burned, and thus it has no energy value). Most vegetables, fruits, and meats, for example, are mostly water. The average metabolizable energy contents of the three basic food groups are 4.2 MJ/kg (1.0 Calories/g) for carbohydrates, 8.4 MJ/kg (2.0 Calories/g) for proteins, and 33.11 MJ/kg (7.9 Calories/g) for fats. Note that 1 kg of natural fat contains almost 8 times the metabolizable energy energy of 1 kg of natural carbohydrates. Thus, a person who fills his stomach with fatty foods is consuming much more energy than a person who fills his stomach with carbohydrates such as bread or rice.
Theoretically, if you measured and weighed everything you ate very carefully and knew the exact proportions of Carbs:Protein:Fat of it all, you could calculate exactly how much energy you consumed, and this is what websites like FitDay and TheDailyPlate aim to do. But you would still be largely in the dark as to what your body does with that energy. That is, you would still know nothing of the hormonal and metabolic processes that determine whether the energy consumed will be stored as fat, excreted, or burned through physical activity and heat dissipation. And there is more to it than simply your Basal Metabolic Rate (BMR) and work, exercise, etc., because the proportion and particular type of macronutrients you consume also has an effect on the energy you burn, and some suggest even on your propensity to perform physical activity following meals (e.g. restlessness).

There are some limits on how much energy can be converted to fat mass in a typical 24 hour period, although I imagine it would be quite difficult and painful to even approach those limits. Your body wants to maintain homeostasis, i.e. its current "normal" state of operation, and any attempt to sway it either direction will be met with resistance. Hence, the difficulty for overweight/obese people to lose weight, and for skinny people who dream of muscle mag covers to pack on pounds.
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Old 12-29-2009, 09:38 AM   #4
Gerhard Lavin
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Re: Nutrition Guru, Total Calories In vs Weight Gain and Loss Question.

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