Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Medical How much calories i need to burn to lost 1 lbs. of body fat?

  1. Dec 14, 2011 #1
    as title says
     
  2. jcsd
  3. Dec 14, 2011 #2
    About 4000.
     
  4. Dec 14, 2011 #3
    if you use energi and e= mgh and remember that the body is about 75% efficient. you can burn as much calories you want. just by lifting things over your head. which is about 2m.
     
  5. Dec 14, 2011 #4

    Evo

    User Avatar

    Staff: Mentor

    One pound of fat is 3,500 calories. To lose a pound, in essense, you need to eat 3,500 calories less than you need.

    In weight loss, other factors such as metabolism, water held in fat, etc... will affect how quickly and effectively you lose the weight.
     
  6. Dec 14, 2011 #5
    I saw 3500 on some pediatrics website, and wolfram alpha said about ~4000. Is there a better source?
     
  7. Dec 14, 2011 #6

    Evo

    User Avatar

    Staff: Mentor

    It has always been 3,500 calories since that unit of measurement came into use, to my knowledge.

    http://www.mayoclinic.com/health/calories/WT00011

    http://science.education.nih.gov/su...508/dbalance/reference/dbalance_ref.htm#sec2c

    I have no idea what wolfram alpha is doing to come up with a different value, I have never seen 4,000 calories.
     
  8. Dec 14, 2011 #7
    i swim twice a week, hike 10 miles every weekend, but still not losing much weight. in fact, i gained 3 lbs since Thanksgiving, wtf

    trying to figure out a realistic workout schedule to stay fit and in shape, ideally i'd like to lose 5~10 lbs
     
  9. Dec 14, 2011 #8

    Evo

    User Avatar

    Staff: Mentor

    How many calories do you consume per day? How many calories do you estimate you burn per day? There are guides all over the internet that will help you calculate your calorie expenditure for certain activities based on your gender, height and weight. There are factors to consider such as metabolism, for example, a person with more muscle will normally burn calories more efficiently than a person with more fat.
     
  10. Dec 14, 2011 #9
    my typical daily meal intake is like this:

    1 cup of oatmeal in the morning
    1 footlong sandwich with all the bells and wistles (sometimes buffet or hamburger)
    dinner i usually skip, just some fruits and maybe a ramen cup noodle

    i'm a guy in my 30s, weight about 155 lbs, height 5'7''
     
  11. Dec 14, 2011 #10

    Evo

    User Avatar

    Staff: Mentor

    If you are more muscle than fat, that's not a bad weight for your height. Why are you concerned?
     
  12. Dec 14, 2011 #11

    Drakkith

    User Avatar

    Staff: Mentor

    I'm about your height, about the same weight, and I don't work out nearly as much as you do. I'm betting that you are mostly muscle, not fat. So no need to lose any weight!
     
  13. Dec 14, 2011 #12

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    Keep in mind that the human body stores energy as fat, which has a dietetic calorie content of 9 kcal/g. Thus, to 'lose a pound of fat' implies that 4032 kcal worth of stored fat is used.

    Now: loss of fat also entails loss of water (the blood that supplies adipose tissue is decreased), 9 kcal/g is the energy content of some sort of fat burned in a calorimeter and may not be truly equivalent to the fat content of adipose tissue and the process of metabolism, energy is not only stored as fat but also glucose, glycogen, and ultimately ATP.

    So, numbers between 3500 and 4000 kcal (or Calories) are *very* reasonable.
     
  14. Dec 14, 2011 #13

    Evo

    User Avatar

    Staff: Mentor

    When you lose weight, you lose glycogen first. You don't burn stored fat first, stored fat is actually the last thing you burn.
     
    Last edited: Dec 14, 2011
  15. Dec 15, 2011 #14

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    The body typically has a total of 700 g (3000 kcal) worth of glycogen at any moment- it is a tiny fraction of the total amount of stored energy. Although you do indeed catabolize glycogen first to extract energy, glycogen stores are then replenished by conversion of lipid stores.
     
  16. Dec 15, 2011 #15

    Evo

    User Avatar

    Staff: Mentor

    Correct,
    Mainly I wanted the OP to know that contrary to all off the internet "burn fat instantly" hype that stored fat is the last to go. I'm a woman, we know these things. :tongue2:
     
  17. Dec 15, 2011 #16

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    I think I'm offended by your blatant sexism ;)
     
  18. Dec 15, 2011 #17

    Drakkith

    User Avatar

    Staff: Mentor

    Be offended later...I need to write this down...Evo...Woman...Fat...got it.
     
  19. Dec 15, 2011 #18

    Evo

    User Avatar

    Staff: Mentor

    Drakkith...member...soon to be non-member... :tongue2:
     
  20. Dec 15, 2011 #19

    Drakkith

    User Avatar

    Staff: Mentor

    I'm confident I can outrun your-[Error: Member Deleted]
     
  21. Dec 15, 2011 #20

    Evo

    User Avatar

    Staff: Mentor

    :biggrin: :rofl:
     
    Last edited: Dec 15, 2011
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: How much calories i need to burn to lost 1 lbs. of body fat?
  1. Metabolism of body fat (Replies: 4)

Loading...