Cardio isn't for "fat burning".
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Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
I don't see how that is so out of the question. You don't think that someone who is 100 lbs overweight can lose almost a pound of fat per day? Someone who is only 20 lbs overweight can only have a 620 cal deficit per day before cutting into lean mass. It would be really frustrating if it were much lower.0 -
Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
The rate is in some doubt but it shouldn't be too much lower or higher from what I've seen of it. However, it doesn't mean there will be zero muscle catabolism below that rate as I alluded to previously so the maximum amount of fat oxidation per pound of fat doesn't tell the full story to how a person might lose musle in practise. Protein needs to be regenerated every 24 hours and skeletal muscle has mechanisms that reduce or enhance the amount of muscle protein regeneration depending on factors such as exersion and available energy through eating. So you can oxidize all the fat you want and still lose muscle if you aren't overcoming the downregulators that reduce the amount of muscle you can regenerate. This means you can be well within your ability to utilize fat and still lose muscle, which definitely does happen unless you take measures to preserve muscle such as lifting wieghts.
I hope this makes sense now.0 -
I always tell friends of mine struggling with weight issues that if they want to lose, they need to start in the kitchen.0
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I quit following this thread some 10 pages ago, but FWIW.
I worked out 5 times last week for a total of 4hours 45 minutes. Assuming I burned 10 cals per minute (which is on the high side of reasonable), I burned about 2850 calores, or about .8lb. Almost 5 hours for less than 1lb? I don't consider that an efficient method of fat/weight loss.0 -
robertw486 wrote: »
But it is a concern, even for a lightly active overfat person.
The common wisdom regarding a safe deficit seems to be 20% off of TDEE. So, in this example, a 20% deficit for this particular woman would be 394 kcal/day (1970 *0.20 = 394). This would put her calorie intake at 1576.
If, on the other hand, she followed a 1200 kcal diet, which many woman latch onto as the "standard" diet regimen, then her deficit is now 770 kcal. And, we know that many women who have a "goal" of 1200 actually eat less than that some of the time, perhaps coming in at 1150 or 1100 or worse. (It isn't advisable to do this because presumably it becomes more and more difficult to get adequate macro and micro nutrition at lower and lower intakes.)
So, maximum fat oxidation is a concern, even in a fat, lightly active individual. Is this woman catabolizing her muscle mass when she consumes 1100 or 1150 kcal, because indeed real world maximum fat oxidation is FAR less than 31 kcal/pound of body fat?
I don't know, but my guess is yes.
I think it could be a concern, especially with larger deficits. Based on the example you give below...
....
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
......then the fat store calories could only provide 1.2 calories per minute. Any activity above that level, which is already less than TDEE, would have to be supplied by the glycogen stores and the food the person is eating day to day. Depending on the total dietary deficit and the macro ratios, the ability to restore the glycogen might be limited to doing so slowly. Being that a person 160 pounds can easily require calories well above 1.2 per minute in even mild forms of exercise, the energy from sources other than the fat have to make it up.
I do not understand your response. What is the source of 1.2 kcal per minute? How does this relate to my question? Sorry for being dense, here.
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I think the original post was mis-interpreted by some as meaning meeting TDEE AND working out does not reduce fat. I read it as you eat to TDEE, your are dead even, and in maintenance. You exercise and now you are in deficit. So you lose weight. The basic statement that "cardio doesn't burn fat" just freaks people out.
The OP says a couple of posts later that is because the health industry, mainly the mags and product makers. They offer plenty of confusion. They sell you "fat burning" workouts or pills. They don't explain about the diet numbers.
My gal and I read the mags. She likes to see the different workout ideas. I like to see if they have any useful data and some of the gals look good ;-) She also went right off when I said, cardio doesn't burn fat. She was like WTF do you mean, that's stupid. I eat clean, stay the calorie number we agreed on, and exercise. I've lost 25lbs. So I know you're just messing with me...
The explanation in more detail was then acceptable. Simply saying "cardio doesn't burn fat" just confuses people and they react quickly and negatively. Not everyone on here had a degree in health and nutrition and didn't immediately pick up on what the OP meant. Just my 2 cents worth.
This is the exact issue with the OP and why this thread keeps on keeping on.0 -
Wheelhouse15 wrote: »
Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
The rate is in some doubt but it shouldn't be too much lower or higher from what I've seen of it. However, it doesn't mean there will be zero muscle catabolism below that rate as I alluded to previously so the maximum amount of fat oxidation per pound of fat doesn't tell the full story to how a person might lose musle in practise. Protein needs to be regenerated every 24 hours and skeletal muscle has mechanisms that reduce or enhance the amount of muscle protein regeneration depending on factors such as exersion and available energy through eating. So you can oxidize all the fat you want and still lose muscle if you aren't overcoming the downregulators that reduce the amount of muscle you can regenerate. This means you can be well within your ability to utilize fat and still lose muscle, which definitely does happen unless you take measures to preserve muscle such as lifting wieghts.
I hope this makes sense now.
Thank you for responding. Yes, it does make a bit more sense now (although that degree in physiology might have come in handy for me about now, if I had gotten one, haha).
My gut feeling was that muscle catabolism would factor heavily with large deficits, which you confirm. What I hear you saying is that although 31 kcal/pound fat oxidation is indeed possible, it may not occur due to other factors.
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Wheelhouse15 wrote: »
Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
The rate is in some doubt but it shouldn't be too much lower or higher from what I've seen of it. However, it doesn't mean there will be zero muscle catabolism below that rate as I alluded to previously so the maximum amount of fat oxidation per pound of fat doesn't tell the full story to how a person might lose musle in practise. Protein needs to be regenerated every 24 hours and skeletal muscle has mechanisms that reduce or enhance the amount of muscle protein regeneration depending on factors such as exersion and available energy through eating. So you can oxidize all the fat you want and still lose muscle if you aren't overcoming the downregulators that reduce the amount of muscle you can regenerate. This means you can be well within your ability to utilize fat and still lose muscle, which definitely does happen unless you take measures to preserve muscle such as lifting wieghts.
I hope this makes sense now.
Thank you for responding. Yes, it does make a bit more sense now (although that degree in physiology might have come in handy for me about now, if I had gotten one, haha).
My gut feeling was that muscle catabolism would factor heavily with large deficits, which you confirm. What I hear you saying is that although 31 kcal/pound fat oxidation is indeed possible, it may not occur due to other factors.
Yes, but we can't assume that all of the missing protein went to energy, it might have been used to replace other tissues.0 -
My bad on the TDEE and exercise part. I messed that up. See, easy to do when you don't do this everyday for a living ;-) I have BMR and TDEE calculated from using IIFYM. I forgot that workouts do count to TDEE. I've gotten lazy because we just use MFP to do it. So she sees she has calories left over each day and is happy.
I can say for fact, regardless of formulas and all that. She did cardio a lot, but failed in the food area. Since changing our diet and exercise. She got down to her smallest size in years. She's really happy with it and now lives with the idea of diet AND exercise. She's lost fat all over. But telling her cardio doesn't burn fat just went right over the top. So I can see how most people would react negatively to that statement. Then they shutdown and don't want to hear anymore.0 -
So at what point can we break CICO? If a person binges on something extreme like 7000 calories at a sitting, they are not going to metabolize that into 2 pounds of fat overnight. At some point, the body will not be able to keep up and will just ship it out the back end. Where is that point?
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Wheelhouse15 wrote: »
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
It's a, perhaps theoretical, maximum. If you are an athlete burning a few thousand calories and trying to make weight it can be of concern since they would be interested in knowing when they might be catabolizing muscle. For a lightly active person trying to lose some fat it's not likely to be as much of a concern.
ETA for me I could oxidize about 500 calories of fat a day so it's a concern for me if I want to cut.
But it is a concern, even for a lightly active overfat person.
The common wisdom regarding a safe deficit seems to be 20% off of TDEE. So, in this example, a 20% deficit for this particular woman would be 394 kcal/day (1970 *0.20 = 394). This would put her calorie intake at 1576.
If, on the other hand, she followed a 1200 kcal diet, which many woman latch onto as the "standard" diet regimen, then her deficit is now 770 kcal. And, we know that many women who have a "goal" of 1200 actually eat less than that some of the time, perhaps coming in at 1150 or 1100 or worse. (It isn't advisable to do this because presumably it becomes more and more difficult to get adequate macro and micro nutrition at lower and lower intakes.)
So, maximum fat oxidation is a concern, even in a fat, lightly active individual. Is this woman catabolizing her muscle mass when she consumes 1100 or 1150 kcal, because indeed real world maximum fat oxidation is FAR less than 31 kcal/pound of body fat?
I don't know, but my guess is yes.
There is still glycogen and circulating energy sources (glucose, fatty acids, amino acids and some intermediary substrates of the various metabolic pathways) and fat globules are stored in nearly every cell in the body that has mitochondria. Plus, the individual is eating - more energy sources come in as food is digested.
It ends up not being a concern in that scenario.
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robertw486 wrote: »
But it is a concern, even for a lightly active overfat person.
The common wisdom regarding a safe deficit seems to be 20% off of TDEE. So, in this example, a 20% deficit for this particular woman would be 394 kcal/day (1970 *0.20 = 394). This would put her calorie intake at 1576.
If, on the other hand, she followed a 1200 kcal diet, which many woman latch onto as the "standard" diet regimen, then her deficit is now 770 kcal. And, we know that many women who have a "goal" of 1200 actually eat less than that some of the time, perhaps coming in at 1150 or 1100 or worse. (It isn't advisable to do this because presumably it becomes more and more difficult to get adequate macro and micro nutrition at lower and lower intakes.)
So, maximum fat oxidation is a concern, even in a fat, lightly active individual. Is this woman catabolizing her muscle mass when she consumes 1100 or 1150 kcal, because indeed real world maximum fat oxidation is FAR less than 31 kcal/pound of body fat?
I don't know, but my guess is yes.
I think it could be a concern, especially with larger deficits. Based on the example you give below...
....
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
......then the fat store calories could only provide 1.2 calories per minute. Any activity above that level, which is already less than TDEE, would have to be supplied by the glycogen stores and the food the person is eating day to day. Depending on the total dietary deficit and the macro ratios, the ability to restore the glycogen might be limited to doing so slowly. Being that a person 160 pounds can easily require calories well above 1.2 per minute in even mild forms of exercise, the energy from sources other than the fat have to make it up.
I do not understand your response. What is the source of 1.2 kcal per minute? How does this relate to my question? Sorry for being dense, here.
I took the below information from one of your other posts....
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
..... and simply converted the 1736 kcal per day you came up with, to kcal per minute.
1736 (estimated fat oxidation in your example / 1440 (minutes in a day = 1.2 calories of fat oxidized per minute
A 160 pound person walking just 2 mph burns around 3 calories a minute, over twice the rate at which the fat can oxidize for use. But the energy has to come from somewhere, so the extra energy needed comes from carb stores in the form of glycogen. Most estimates are that the average person has around 1,500 - 2,000 calories of glycogen stores in their muscle and organs (mostly liver).
Think of it as a human having two fuel tanks. You always use fuel from both excepting extreme conditions. But if one tank runs low or runs out, you don't have as much energy available to use. Even if both tanks have enough energy to provide, what you eat will at least partially go towards refilling the tank that is low.
Fat will supply only limited amounts of energy, so even if the fat "tank" is still near full, the glycogen "tank" gets depleted and must be refilled as you eat.
Below is a quote from earlier in the thread that might make more sense of the fuels being used. The CHO shown on the chart is carbs in the form of glycogen.robertw486 wrote: »Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
The max is in the neighborhood of 30-32 calories per pound of fat, in a 24 hour period. This goes to show just how fat helps with long term energy, but not short term energy.
**Note** First easy to read chart I found, variance in crossover points for fuels used can be from 45-75% of VO2max
The above displays one of @Ninerbuff 's first points. At any level most of us would call "cardio" exercise, we are burning both fat and carbs as the fuel. Though some change can be made on RER through training, no matter where the crossover points are, as intensity goes up, so does carb use. Those glycogen stores are helping you get through a cardio session, even at lower intensities.
When you eat, the body will replenish glycogen, and if you eat in a deficit, not replenish all the fat stores you burned. If at maintenance, both would replenish fully. If in surplus, all glycogen plus greater fat stores.
Keep in mind that that is the theory, someone skewed in real life by diet composition, how you spread the intake out, muscle repair needs, etc. It's not as if the food you eat would automatically replenish all lost glycogen immediately, and then possibly restore the fat lost. If you exercised at a level of intensity high enough for a complete "bonk" type experience, it might take a couple days or more to fully recover glycogen stores, even if eating at TDEE.
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what type of food you eat does not make you fat, it is the number of caloriesPeople these days eat straight up crap. Chips, soda, hot dogs, McDonald's, and everything else. Never a veggie or a fruit oh how about some old fashioned water and a good run around the block. Take account for the things you consume or they will consume you with obesity and disease.
cardio does not burn fat but it does create a greater calorie deficit when you count calories and that helps me lose weight, so i'll keep cardio-ing
Me too!! And I'll keep eating healthy and try to limit the junk.
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Not sure where 1.2 cal/min max fat came from that is being bounced around.
To the amount of fat oxidation to carb oxidation - my VO2max test during the walking period.
3mph & 0.5 % grade.
4.397 cal/min total burn.
carb 1.262 cal/min
fat 3.135 cal/min
In fact during these results I'm looking at - fat got up to a max of 7.15 cal/min while carb was at 1.813 cal/min.
That was 3 mph @ 10.7% grade.
After that fat starting coming down slowly as carbs went up a tad faster.
Was it ever mentioned that the "study" that came up with the 31 cal/lb of fat was merely a math exercise looking at another study and it's results, seeing if they could find a formula that fit the results seen?
I'm glad several have mentioned the math either doesn't work out in some cases, or you can risk LBM and probably muscle mass (different things, right?) even if not nearing that max.
Ditto's to the glycogen refill taking awhile too - that's why the few studies have shown that after endurance cardio, if planning to do it again tomorrow - benefits from a post exercise recovery snack of carbs:protein ratio 4:1 within 30 min of the workout. And more within 2 hrs.
Also in that nice description above - keep in mind that muscle glucose stores can only be used for the muscle - they can't be dumped back into the blood stream to help elsewhere or makeup for low liver stores.
That's the first dazed thinking you get in an endurance cardio event, low blood sugar from low liver stores.
The "bonk" and "wall" come later when the muscle glucose stores are almost gone too - and body is going to slow you down to the pace the available fat can supply the energy needs, plus amino acids floating around for use.0 -
BMR is an "at rest" count for calories (basically sitting on the couch or laying in bed for the whole day). Most people will be right around 1400-1500 a day on average. Now add in other low intensity activity to the count and as well as any other physical activity, that number could easily be at 1700 or more. And the primary fuel for BMR and low intensity activity (walk to the bathroom, walk to the kitchen, driving your car, etc.) is fat.
Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
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I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
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????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
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Well if I did that, bathroom breaks would be at least 3-4 times the next day. The body is very efficient at storing energy so it's kinda hard to say. Just about anything we eat will cause insulin to be released and excess calories will be stored.So at what point can we break CICO? If a person binges on something extreme like 7000 calories at a sitting, they are not going to metabolize that into 2 pounds of fat overnight. At some point, the body will not be able to keep up and will just ship it out the back end. Where is that point?
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0 -
Well if I did that, bathroom breaks would be at least 3-4 times the next day. The body is very efficient at storing energy so it's kinda hard to say. Just about anything we eat will cause insulin to be released and excess calories will be stored.So at what point can we break CICO? If a person binges on something extreme like 7000 calories at a sitting, they are not going to metabolize that into 2 pounds of fat overnight. At some point, the body will not be able to keep up and will just ship it out the back end. Where is that point?
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I can't remember where but I read that the average person could make use of about 25k calories in a 24 hour period give or take. So, yes, I think you can store several pounds of fat from one ridiculous binge.0 -
BMR is an "at rest" count for calories (basically sitting on the couch or laying in bed for the whole day). Most people will be right around 1400-1500 a day on average. Now add in other low intensity activity to the count and as well as any other physical activity, that number could easily be at 1700 or more. And the primary fuel for BMR and low intensity activity (walk to the bathroom, walk to the kitchen, driving your car, etc.) is fat.
Sounds about right. Remember we burn more fat calories at rest than exercising. Most people will exercise 30-60 minutes a day on average so that leaves 23 hours of time that we are at rest or low intensity of physical activity.
Thanks for this. I remember covering this back in college (a long time ago).Protranser wrote: »Isn't there some knowledge floating around these forums that describes a maximum amount of fat that the oxidized per day?
If there is a maximum amount of fat that can be oxidized per day, and, one exceeds the oxidation maximum through calorie deficit, what happens when you exceed the maximum oxidation limit? Where does the energy come from if not fat?
Estimation is the maximum fat oxidation per day is 31 calories per pound of body fat per day.
Unfortunately, that number is based on standard physiology (a weight lifter with above average lean mass probably has a higher limit) and up to moderate amounts of exercise - bouts of high intensity exercise might allow exceeding this limit, particularly in an individual with the physiological adaptations that would allow such bouts to occur. For the most part, 31 kCal/pound body fat/day represents a deficit limit for people mainly losing via dietary calorie cutting versus neat, and not someone looking to lose weight via excess exercise.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
I have read this before, but this is hard for me to believe or understand.
Let's run some real numbers.
Let's take a 5'4" lightly active, 30-year old woman of 160 pounds and 35% body fat. This gives her 56 pounds of body fat (160 * 0.35 = 56). Her BMR is on the order of 1430 and her TDEE is on the order of 1970.
31 kcal per pound of body fat would be 1736 kcal (31*56 = 1736).
Something tells me that real world maximum fat oxidation is FAR less than 31 kcal per pound.
(Edited with slightly different numbers.)
Subtract 1736 from 1970 and you have 234 calories still in surplus. Also take into consideration some fat is restored through the eating process even though there may be a calorie deficit.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
????
@ninerbuff I that perhaps think you read through my post too quickly. Could you please reread it and respond again?
I am not sure that I understand your response to me and I think it is because you misunderstood what I wrote.
I am questioning the validity of a 31 kcal/pound fat oxidation rate. I do not think that that rate is realistic. Using her TDEE of 1970 and her fat store of 56 pounds, are you saying that she could consume a mere 234 calories per day and live off her fat stores at the oxidation rate of 1736 kcal per day (56 x 31). People have survived on tiny amounts of food during famines. However, she truly would be starving.
My whole point is that 31 kcal/pound of fat seems way, way too high to me. My suspicion is that real world fat oxidation rates would more likely much, much lower before muscle catabolism starts. But I haven't studied physiology so what do I know? It just seems like 31 kcal/pound is super high to me.
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@ninerbuff You still misread my post. Or maybe you didn't read it at all.
I understand what both BMR and TDEE are.
What I was questioning was the idea that maximum fat oxidation could be as high as 31 kcal per pound of body fat per day. My supposition was that maximum fat oxidation rates in the real world are far, far less than 31 kcal per pound.
I have seen this 31 kcal per pound of body fat figure used elsewhere online to justify the amount of a deficit.
For example, saying that a 180 pound man with 15% bodyfat (27 pounds) with a TDEE of 2700 kcal could sustain a deficit of 837 kcal per day (31% of his TDEE) because he could oxidize 31 kcal per pound of body fat per day (27 * 31 = 837). (Here's the link to the example I read: http://mindandmuscle.net/articles/determining-the-maximum-dietary-deficit-for-fat-loss/ Oh, and what do you know, it's by Lyle McDonald.)
My whole issue was disputing this 31 kcal per pound of body fat oxidation level.
In the example I gave, the 160 pound woman has a TDEE of 1970 and 35% body fat (56 pounds). I was disputing a maximum fat oxidation level of 31 kcal/pound of body fat, because in her case, 31 kcal per pound of body fat would equal 1736 calories. An intake of 1100, 1150 or 1200 calories (something that is not uncommon in some women who glom onto a calorie goal of 1200 kcal/day while on a diet), would result in a a deficit of 870 or 820 or 770 (far below the this theoretical maximum fat oxidation level deficit of 1736 or 31 kcal * 56 pounds of body fat). These would be huge deficits for her, and my guess is that it would result in a much larger amount of muscle loss than with much smaller deficits.
If 31 kcal per pound of body fat were a real world fat oxidation rate, then she would theoretically be able to sustain a deficit of 1736 calories (eating only 234 calories). 1970 TDEE less 1736 supposed maximum fat oxidation = 234.
Do you understand now why I was questioning this fat oxidation rate?
Even if she were highly trained and was lifting in a progressive lifting program to preserve muscle mass, I don't believe that there is any way she would be capable of oxidizing 31 kcal/pound of body fat.
But again, maybe I don't understand.
In any case, this obviously wasn't on topic with the original subject of the thread. I only questioned it because it was brought up by another poster elsewhere in this thread. However, it is off topic and it's been beaten to death, so just forget about it. You don't need to respond further.
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Was it ever mentioned that the "study" that came up with the 31 cal/lb of fat was merely a math exercise looking at another study and it's results, seeing if they could find a formula that fit the results seen?
I'm glad several have mentioned the math either doesn't work out in some cases, or you can risk LBM and probably muscle mass (different things, right?) even if not nearing that max.
@heybales Somehow, I didn't see this post before I replied again to @ninerbuff just above.
THANK YOU, yes, my whole problem with the 31 kcal/lb of body fat was that the math just did not seem to work at all, especially in the example of the woman that I gave.
I do not have access to the original study (Alpert SS. A limit on the energy transfer rate from the human fat store in hypophagia. J Theor Biol. 2005 Mar 7;233(1):1-13.) because you have to pay to get a copy of the full report. I skimmed the abstract, but did not originally pick up on the key word "deduced" and therefore I glossed over that it was "merely a math exercise" as you put it.
It may work as a math exercise, but I don't think that there is any way that it works in the real world. Again, thanks for understanding where I was coming from.
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Was it ever mentioned that the "study" that came up with the 31 cal/lb of fat was merely a math exercise looking at another study and it's results, seeing if they could find a formula that fit the results seen?
I'm glad several have mentioned the math either doesn't work out in some cases, or you can risk LBM and probably muscle mass (different things, right?) even if not nearing that max.
@heybales Somehow, I didn't see this post before I replied again to @ninerbuff just above.
THANK YOU, yes, my whole problem with the 31 kcal/lb of body fat was that the math just did not seem to work at all, especially in the example of the woman that I gave.
I do not have access to the original study (Alpert SS. A limit on the energy transfer rate from the human fat store in hypophagia. J Theor Biol. 2005 Mar 7;233(1):1-13.) because you have to pay to get a copy of the full report. I skimmed the abstract, but did not originally pick up on the key word "deduced" and therefore I glossed over that it was "merely a math exercise" as you put it.
It may work as a math exercise, but I don't think that there is any way that it works in the real world. Again, thanks for understanding where I was coming from.
Was the study of men? I would assume do to higher testosterone levels that men could oxidize more fat prior to eating into muscle as testosterone itself if muscle sparing/building.0
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