Confused about calorie math

nelinelineli

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.

Adrianachiarato

Are you Brazilian?

SkimFlatWhite68

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

SkimFlatWhite68

I was thinking Australian.

rayonrainbows

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....

Adrianachiarato

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?

nelinelineli

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!

Adrianachiarato

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.

MrsFowler1069

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.

nelinelineli

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:)

MrsFowler1069

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.

joshdann

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.

nelinelineli

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.

joshdann

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.

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.

Vailara

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.

EvgeniZyntx

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.

nelinelineli

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.

nelinelineli

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.

Adrianachiarato

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.

igotabulletproofheart

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.

Adrianachiarato

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.

watfordjc

1 lb of body fat is not 100% fat, the same as 1 lb of muscle is not 100% protein.

Hoping Google can stop me from looking for the research again...

http://www.myfitnesspal.com/topics/show/816892-drop-10-pounds-in-30-days-the-math-behind-it

Adipose tissue is not 100% fat. To quote http://www.sportsci.org/encyc/adipose/adipose.html :

"Approximately 60 to 85% of the weight of white adipose tissue is lipid, with 90-99% being triglyceride. Small amounts of free fatty acids, diglyceride, cholesterol, phospholipid and minute quantities of cholesterol ester and monoglyceride are also present. In this lipid mixture, six fatty acids make up approximately 90% of the total, and these are myristic, plamitic, palmitoleic, stearic, oleic, and linoleic. Varying the composition of your diet can vary the fatty acid profile in adipose tissue. The remaining weight of white adipose tissue is composed of water (5 to 30%) and protein (2 to 3%)."

Human muscle is about 16-21% protein.

Since the variability between people (and cells within the same person) make it impossible to determine the exact caloric value without dissection (and in the case of muscle, even the dissection method uses estimates since separating fat from within muscle fibre is too difficult), and the math to do it is too complex for me, I trust the averages of 3,500 kilocalories per pound of fat and 600 kilocalories per pound of muscle.

ETA: That is for losses and gaining fat, I'm not sure what the averages are for regaining muscle and gaining muscle. 2,500 kilocalories seems to be touted for bulking, but I think that is the "pound of muscle plus some fat gain that you'll later lose when cutting" figure.

Approximately 3,500 kcal per pound, so 3,500 / 0.454 = approximately 7,709.25 kilocalories per kilogram of body fat. There are 454 grams in a pound, so you don't really need a source saying how many calories are in a kilogram of body fat because we know how to convert between weighing systems.

Whether you go with 7700, 7710, 7709.25, or 7709.2511013215859030837004405286 kcal per kg, it probably doesn't matter because 3,500 kcal per lb is an approximation itself... 7,700 is a nice round number. To my knowledge, the exact number would be impossible to determine because even if there was a sci-fi scanner that could determine the makeup of all your cells you have no idea which cells would make up the next kilogram you lose.

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.

Seeing the number 9, it is feasible they meant/said/recalled 9 kilocalories per gram of fat. Can't be sure though.

If going with metric, I suppose the one thing to bear in mind is that a seventh of 7,700 is 1,100, so the metric goals on MFP are slightly more than the imperial goals (e.g. 0.5 kg/week ~= 550 kcal/day deficit, 1 lb/week ~= 500 kcal/day deficit).

ETA: It might also be entirely possible the experts don't know how to convert between metric and imperial, or that they don't know white adipose tissue isn't 100% fat. 9,000 calories should equal ~4.086 pounds of body fat, or ~1.855044 kilograms of body fat.

ETA2: Using the estimate of 9 kilocalories per gram of fat, losing 1 pound of body fat could (using the approximate numbers I quoted myself quoting) require a deficit of:

9*454*0.6*0.9 + 4*454*0.02 = 2,206.44 + 36.32 = 2,242.76 calories on the low end.
9*454*0.85*0.99 + 4*454*0.03 = 3,438.369 + 54.48 = 3,492.849 calories on the high end.

So a kilogram of body fat could require a deficit between 4,940 calories and 7693.5 calories, depending on the make-up of the cells utilised.

I have no idea if this is how the 3,500 and 7,700 numbers were reached though. It could be I have missed a multiplier (efficiency of lipolysis?)

Just_Scott

bump for later