Confused about calorie math
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nelinelineli
Posts: 330 Member
Hi there.
I'm from the side of the world that uses kgs and cms, so, when trying to convert the golden "3500 calories for one pound weight loss" rule, I got terribly confused:
1 kg = 2.2 lbs, thus 1 kg weight loss = 3500*2.2 = 7700 cal
But 1g of fat = 9 cal, thus 1 kg of fat = 9000 cal
Thinking it's a matter of "energy STORED in a fat cell vs energy in actual fat", or something of sorts, I've been googling it for few hours, just to discover that both formulas ( 1kg weight loss = 9k cals and 1lb weight loss = 3.5k cals) are used by fitness and medical (internet) professionals, often depending on their preferred unit of measure, meaning that people using the 7700 cal/kg have derived it from the pound formula.
Can anyone enlighten me?
Thank you!
Edit based on comments:
1. For people who are trying to guess where I'm from: I'm originally Romanian, lived in France, now I live in Japan (all countries using metric system)
2. I'm content with my weight loss so far, but I would like to use my (pretty steady) results I've got so far to calculate my real TDEE, and rely less on the estimations.
I'm from the side of the world that uses kgs and cms, so, when trying to convert the golden "3500 calories for one pound weight loss" rule, I got terribly confused:
1 kg = 2.2 lbs, thus 1 kg weight loss = 3500*2.2 = 7700 cal
But 1g of fat = 9 cal, thus 1 kg of fat = 9000 cal
Thinking it's a matter of "energy STORED in a fat cell vs energy in actual fat", or something of sorts, I've been googling it for few hours, just to discover that both formulas ( 1kg weight loss = 9k cals and 1lb weight loss = 3.5k cals) are used by fitness and medical (internet) professionals, often depending on their preferred unit of measure, meaning that people using the 7700 cal/kg have derived it from the pound formula.
Can anyone enlighten me?
Thank you!
Edit based on comments:
1. For people who are trying to guess where I'm from: I'm originally Romanian, lived in France, now I live in Japan (all countries using metric system)
2. I'm content with my weight loss so far, but I would like to use my (pretty steady) results I've got so far to calculate my real TDEE, and rely less on the estimations.
0
Replies
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Are you Brazilian?0
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OMG, I'm from your side of the world too (I think) but I got lost right after you got terribly confused..
Basically I can see that you have 4kg to lose. All you need to do is work out your TDEE and cut 500 calories a day from that and in 8 weeks you will be somewhere around your goal. That's what I would do. No need to complicate it further.
I hope someone can help you out with the maths part of the question 0 -
I was thinking Australian.0
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hey there
i really have no idea but 1g of fat = 9 calories
1g of protein = 4 calories
1g of carbs = 4 calories
those only average out to 5.67 (not 7.7) but i wonder if that might be a hint in the right direction?
seriously though, just a total guess....0 -
I use the same numbers to estimate how much weight I will lose, only never thought about 1g of fat having 9 calories. I guess it does when you eat it, but for the body to use it up it might involve some process which spends the extra 2 cal/g?0
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OMG, I'm from your side of the world too (I think) but I got lost right after you got terribly confused..
Basically I can see that you have 4kg to lose. All you need to do is work out your TDEE and cut 500 calories a day from that and in 8 weeks you will be somewhere around your goal. That's what I would do. No need to complicate it further.
I hope someone can help you out with the maths part of the question
Yes that part is kinda covered, but now since I've had pretty steady losses and fixed intake, I would like to figure out my TDEE based on actual loss instead of going with the estimations. It's not a life and death issue, but it would be so good to know because this "small error" equates to 185 extra calories a day on my TDEE. Call it nerdy curiosity! 0 -
I can't cut that many calories so I guess she/he can't either. If I did I'd be consuming only 1000/day which isn't a good move.0
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Are you Brazilian?
Martian. lol
No, seriously OP....I think you're not so far off as it sounds. It does sound terribly confusing. :laugh:
My understanding is that 1 gram of fat consumed as a dietary component provides 9 calories, as a measurement of the energy it provides to your body.
*and*
3500 calories consumed in excess of TDEE (or unused available energy) will lead to roughly one pound of body fat, or weight gained - not fat as a dietary component or macronutrient.
*and*
In regard to the pounds/kilograms conversion, I believe your math is correct. Or your maths are correct. Depending. lol
Does that make sense? Anyone?
Edited to add:
And did I even understand your question? Because by the time I finished posting, the conversation seemed to have gone another direction.0 -
Are you Brazilian?
Martian. lol
No, seriously OP....I think you're not so far off as it sounds. It does sound terribly confusing. :laugh:
My understanding is that 1 gram of fat consumed as a dietary component provides 9 calories, as a measurement of the energy it provides to your body.
*and*
3500 calories consumed in excess of TDEE (or unused available energy) will lead to roughly one pound of body fat, or weight gained - not fat as a dietary component or macronutrient.
*and*
In regard to the pounds/kilograms conversion, I believe your math is correct. Or your maths are correct. Depending. lol
Does that make sense? Anyone?
Yes, that makes sense to me and I was betting my wits on it until I got Google-confused. I searched for articles in French for example, knowing they'd use kgs, and they say 9k cal/ kg of fat loss.
My issue mostly is with the discrepancies between pound related advices and kg related ones. I guess other people got confused as well and polluted the internet:)0 -
Are you Brazilian?
Martian. lol
No, seriously OP....I think you're not so far off as it sounds. It does sound terribly confusing. :laugh:
My understanding is that 1 gram of fat consumed as a dietary component provides 9 calories, as a measurement of the energy it provides to your body.
*and*
3500 calories consumed in excess of TDEE (or unused available energy) will lead to roughly one pound of body fat, or weight gained - not fat as a dietary component or macronutrient.
*and*
In regard to the pounds/kilograms conversion, I believe your math is correct. Or your maths are correct. Depending. lol
Does that make sense? Anyone?
Yes, that makes sense to me and I was betting my wits on it until I got Google-confused. I searched for articles in French for example, knowing they'd use kgs, and they say 9k cal/ kg of fat loss.
My issue mostly is with the discrepancies between pound related advices and kg related ones. I guess other people got confused as well and polluted the internet:)
No! That's crazy talk! lol
Now I am depending on other more sufficiently prepared people than I to provide the appropriate .gif for this moment.0 -
the amount of energy your body can get from breaking down 1g of dietary fat is not quite the same as the amount of energy your body can get from pulling energy from its own fat cells. When you digest a gram of fat, it gets broken down completely (with some waste, of course) into more basic nutrients. When you deplete fat stores, the cells do not really go away (at least not initially), they simply release the stored nutrients into the blood stream and decrease in size. Eventually, those cells can lose their usefulness to the body and be reabsorbed entirely. The studies I've read weren't conclusive if the absorption results in an actual breakdown into usable energy nutrients, or if the cells are simply "flushed" as waste (pun intended).
I *think* the mechanical difference in metabolizing dietary fat versus absorbing nutrients from your own fat cells should account for the difference in math.0 -
I *think* the mechanical difference in metabolizing dietary fat versus absorbing nutrients from your own fat cells should account for the difference in math.
I'm happy with that thought, and It's likely the explanation. I just wish I could find a reliable source to confirm 1 kg = 7700 calories but I guess I'm splitting hairs here.
Back home (long time ago), my dietitian also taught me 9k cal/kg so the "common wisdom" might be a cultural thing. She probably simply didn't know any better.0 -
If you manage to find it, I'd love to see it, too. I've always been skeptical of the magic 3500-per-pound number that everyone quotes as if it is beyond reproach. My personal numbers seem to agree with it, mostly, but of course the inaccuracies inherent in "measuring" calorie burn make that agreeable calculation an educated guess at best.I'm happy with that thought, and It's likely the explanation. I just wish I could find a reliable source to confirm 1 kg = 7700 calories but I guess I'm splitting hairs here.
Back home (long time ago), my dietitian also taught me 9k cal/kg so the "common wisdom" might be a cultural thing. She probably simply didn't know any better.0 -
Just to complicate things further, I think that you don't ONLY lose fat, but also some small amounts of other substances. I also think that the 3500 is an estimate rather than a precisely accurate figure.
What I've found useful, as an experiment, is to carefully track my intake and weigh daily, then look at progress over time. What I found was that according to my calculations, I was losing roughly what I would expect (i.e. a deficit of around 3500 from my calculated TDEE was resulting in approximately a 1lb weight loss). That was good enough for me. In a roundabout way, you could also lose it to work out your TDEE!
I was using the Katch-McArdle BMR calculation, and recently I looked at the Harris-Benedict one - what a difference! I would not have lost weight using H-B. This could be because Katch-McArdle was more accurate for me (I believe I have a higher body fat %) as the K-M figures fitted with my weight loss. (However, I'm aware that it could also have been that I was underestimating intake!).
In the end it doesn't matter: I believe that the results are more important than the initial calculations. The problem with going by the results is that it's a slow process and you need weeks of data. You can't just use a figure for a week and go by your weight at the end of the week. But doing it that way, you're getting personalised feedback. If you find you're losing 1kg a month and that's about right, for instance, then you don't really need to know what your TDEE is and whether you've subtracted 7700 or 9000 - you've found out how much you need to eat to lose at that rate. If you see what I mean.0 -
The 3500 calories number is an estimate of the energy deficit required in 1 lb of loss. It assumes a 70% fat / 30% LBM composition in that loss. It has been simplified as 3500 cals in a lb of lost fat but it's incorrect. It's a good estimate though.0
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Just to complicate things further, I think that you don't ONLY lose fat, but also some small amounts of other substances. I also think that the 3500 is an estimate rather than a precisely accurate figure.
What I've found useful, as an experiment, is to carefully track my intake and weigh daily, then look at progress over time. What I found was that according to my calculations, I was losing roughly what I would expect (i.e. a deficit of around 3500 from my calculated TDEE was resulting in approximately a 1lb weight loss). That was good enough for me. In a roundabout way, you could also lose it to work out your TDEE!
I was using the Katch-McArdle BMR calculation, and recently I looked at the Harris-Benedict one - what a difference! I would not have lost weight using H-B. This could be because Katch-McArdle was more accurate for me (I believe I have a higher body fat %) as the K-M figures fitted with my weight loss. (However, I'm aware that it could also have been that I was underestimating intake!).
In the end it doesn't matter: I believe that the results are more important than the initial calculations. The problem with going by the results is that it's a slow process and you need weeks of data. You can't just use a figure for a week and go by your weight at the end of the week. But doing it that way, you're getting personalised feedback. If you find you're losing 1kg a month and that's about right, for instance, then you don't really need to know what your TDEE is and whether you've subtracted 7700 or 9000 - you've found out how much you need to eat to lose at that rate. If you see what I mean.
Yup, in the end this variable doesn't quite matter, as long as I'm consistent in my calculations and always use the same. I have data over 2 months, and it's pretty consistent, so I think it's a good approximation. I was slightly put off by the fact that, by using the 7700 cal rule, my TDEE is 1573 cal. I'm short and at normal weight so I wasn't particularly surprised. At the end of the day, the absolute value indeed doesn't matter per se.0 -
The 3500 calories number is an estimate of the energy deficit required in 1 lb of loss. It assumes a 70% fat / 30% LBM composition in that loss. It has been simplified as 3500 cals in a lb of lost fat but it's incorrect. It's a good estimate though.
Oh thank you for that, it's actually very interesting and points out one of the reasons people who work out may have slightly different outcomes.0 -
I'm happy with that thought, and It's likely the explanation. I just wish I could find a reliable source to confirm 1 kg = 7700 calories but I guess I'm splitting hairs here.
Back home (long time ago), my dietitian also taught me 9k cal/kg so the "common wisdom" might be a cultural thing. She probably simply didn't know any better.
That's what I've tried to say, I guess your wording is much better than mine.If you manage to find it, I'd love to see it, too. I've always been skeptical of the magic 3500-per-pound number that everyone quotes as if it is beyond reproach. My personal numbers seem to agree with it, mostly, but of course the inaccuracies inherent in "measuring" calorie burn make that agreeable calculation an educated guess at best.
And for me, the maths work just fine. Last time I calculated it was just 2 days ago. Maths said I should have lost 1,45kg in the last 28 days and I've lost 1,6kg. But I've used calories instead of net calories when I did the maths.0 -
Can anyone enlighten me?
Yes. Use lbs and inches.
I'm British. Brits like the metric system but I find lbs and inches easier to use when it comes to weight loss and calculating things to do with it.0 -
Can anyone enlighten me?
Yes. Use lbs and inches.
I'm British. Brits like the metric system but I find lbs and inches easier to use when it comes to weight loss and calculating things to do with it.
Now that's just silly. Conversion has been done already.0
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