If 1 gram of fat has 9 calories...?

Discussion in 'Health and Fitness' started by KidCanFight, Dec 23, 2006.

  1. KidCanFight

    KidCanFight good is not good enough

    I was thinking about this the other day and was hoping someone could tell me if it is right or not. I know that 1g of fat has 9 calories. Does this also apply to body fat?

    According to this site (http://www.sportzblitz.net/calculators/workout-calculator.php) 30 minutes of moderate walking burns 147 calories. Does this mean by walking for 30 minutes you will lose about 16.5g of fat off your body?

    It seems perfectly logical, but I am probably forgetting something stupid.

    So, is this the case?
  2. CosmicFish

    CosmicFish Aleprechaunist

    IIRC, it's generally accepted that one pound of body fat has 3,500 calories.

    However, there are 454 grams in a pound, which come out at (9 X 454) a little over 4,000 calories. To be honest, I'm not entirely sure where the discrepancy comes from (I'd guess it's a rounding error). I'd be inclined to trust the 3,500 calories per pound of body fat measurement, if only because it's so ubiquitous.

    Also, bear in mind that any numbers you get relating to calories burned by exercise will be estimates at best.
  3. acarpe

    acarpe Valued Ember

    bear in mind a certain degree of the activity will be carbohydrate fuelled- as your body's primary energy pathway
  4. SifuJason

    SifuJason Valued Member

    Exercise won't solely burn fat; it will burn carbohydrate and protein (muscle) as well, so it it's not a direct conversion. The discrepancy between the 3,500 and 4,000 calories per pound of fat can have many explanations, but my education guess would be that 4,000 is an over-estimate because of differences in density of storage of fat in our bodies, and that used in the 1 gram = 9 calorie calculation. Also, 1 to 9 calculation is an average overall all fat molecules we are likely to eat, which is not the same as the fat molecules we store.
  5. NaughtyKnight

    NaughtyKnight Has yellow fever!

    It really doesnt matter. Burn off more caloires than you consume and you'll lose weight.

    Dont worry yourself with semantics.
  6. Shrukin89

    Shrukin89 Valued Member

    Also depends on how much you weigh. The bigger you are the more calories you are likely to burn off. More muscles = more burning off fat or excess cals.

    Also of how fast you are walking jogging or running, on average a 100 calories is burned by jogging or running 1 km.

    But I don't think the body burns off entirely on fat, there's gotta be a ratio of some sort.
  7. Shrukin89

    Shrukin89 Valued Member

    and Jason beaten me to it on the last part. (never noticed)
  8. SifuJason

    SifuJason Valued Member

    LOL. Actually the ratio is time dependent. Fat is our long-term storage, we burn that the longer we exercise. Short bursts use mostly sugar (glycogen) stores, and protein is used throughout. It gets annoyingly complicated pretty quickly, since certain reactions are simply in equilibrium and thus are passively driven (mass action), while others respond to hormone stimulation.
  9. KidCanFight

    KidCanFight good is not good enough

    Everything that has been said is very logical.

    Everyone is much smarter than me :(
  10. wudangfajing

    wudangfajing Banned Banned

    An how many hours will it take me to lose 500 LBS of fat? :eek: Not actually that heavy just was wondering so i could set a exact ratio.

    Also, need to include how much i can eat if any food can be eaten during this weightloss thing. :D

    but being that specific seems to be a little hard to do so many factors but possible.
  11. CosmicFish

    CosmicFish Aleprechaunist

    Nah, we've just learned things you haven't yet. Keep asking questions, keep studying and keep learning. ;)
  12. Ad McG

    Ad McG Troll-killer Supporter

    Precisely. It's impossible to actually answer this question because it's different for all individuals and even individuals will vary depending on their body composition, amount of exercise etc.
  13. blessed_samurai

    blessed_samurai Valued Member

    I agree with most of what you've said. However, if we're burning protein (muscle), then we have a problem. Protein should be teh last fuel that is burned. I would say where you'll see protein being utilized as a fuel is in starving individuals and endurance athletes (aka Tour de France).
  14. SifuJason

    SifuJason Valued Member

    Unfortunately, that's not the case. We have 3 fuel sources: carbs, fat, and protein. Carbs go first, and they last about an hour. After that, your liver starts synthesizing glucose from protein stores. Your body also starts to consume fat and protein directly for energy. The problem is that fat can't converted to glucose, and also that fat can't be used for energy in anaerobic conditions, due to the lack of oxygen. Consequently, protein must be used. You are right that starving individuals and endurance athletes burn fat--those are aerobic conditions. Also, your body does keep some muscle in reserve so you can move, etc, in emergency situations and during prolonged starvation.

    However, when you workout, you still burn protein, mostly in the form of muscle.
  15. BGile

    BGile Banned Banned

  16. blessed_samurai

    blessed_samurai Valued Member

    Yes, I realize taht fat cannot be converted to glucose and that fat cannot be utilized as an energy source in an anerobic environment. However, it's been my understanding due to professors and kinesiology books that the body will only resort to burning protein as a last resort in an extremely starved individual or when there are no carbohydrates to be used. I've never heard of the hour rule on running out of carbs. I used the Lance Armstrong analogy because that was the example that was always given to me...the average person whether they're in the gym an hour or two is not in danger of burning muscle as a fuel source because it would take A LOT to deplete glycogen stores-basically a very high caliber endurance athlete or someone in a starved state. Also there is no natural store for protein, just the facilitating of broken down amino acids to body tissues. The only time the body stores it is if you are breaking down muscle tissue on a regular basis, your body will then store it to a small degree still, for future uses. Off to emailing I go to get a clarification on this.

    I do appreciate you bringing it up because I appreciate being wrong...it means I get to learn something. :)
    Last edited: Dec 31, 2006
  17. SifuJason

    SifuJason Valued Member


    Like many (all) things in science, the information is experimental and thus is not always the easiest to wade through and determine "the truth," even if it is known. My information comes from my medical school courses. The general understanding that is being passed onto med students is that glycogen stores last about an hour, which makes sense given their relative lack of density. After that hour, your body mostly burns fat between meals, with a bit of protein being burned as well. However, exercise results in an oxygen-depleted environment which forces the protein to be used.

    A real world example is the "weight loss" people see right after a strenuous work-out of a couple of hours. People cite that as water and fat, and while it is true you loose some water, you don't sweat that many pounds of water (given water weighs 1 gm/mL or 62.4 lbs/sq ft), and a lb of fat is about 3500 calories. The rest of that loss is muscle.

    Carbo loading is another example, where people bulk up their glycogen stores to stave off fat and protein consumption.

    Note, however, that what I am passing on from my classes does not say that working out causes a net decrease in muscle; short-term muscle loss and strain leads to increased muscle mass, as we all know.

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