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Are short fasts really helpful for burning fat?
dykask
Posts: 800 Member
I'm talking about fast less than 2 days in length, probably more like 16 hours most of the time.
Let's say you eat lunch, then nothing until breakfast the next morning. Maybe 20 hours of fasting. I've tried this and it isn't that hard to pull off and my general experience is it does seem to promote fat loss.
What do you think? Does a short fast really help with fat loss or is it harmful someway?
Let's say you eat lunch, then nothing until breakfast the next morning. Maybe 20 hours of fasting. I've tried this and it isn't that hard to pull off and my general experience is it does seem to promote fat loss.
What do you think? Does a short fast really help with fat loss or is it harmful someway?
3
Replies
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Well it depends. Is that lunch 2000 calories?
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
4 -
Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.0 -
Here is a thought. While fasting your insulin goes down to your fasting level. (Unless you are type 1 diabetic you always have some insulin in your blood.) The lower this level the easier it is for your body to use fat stores. By increasing the hours without comsumig food, maybe the fasting insulin goes lower over time allowing for more fat to be used.
Anyway that seems to be a common claim.9 -
Here is a thought. While fasting your insulin goes down to your fasting level. (Unless you are type 1 diabetic you always have some insulin in your blood.) The lower this level the easier it is for your body to use fat stores. By increasing the hours without comsumig food, maybe the fasting insulin goes lower over time allowing for more fat to be used.
Anyway that seems to be a common claim.
I think this can be helpful in mobilizing stubborn fat (fasting can inhibit the alpha-2 receptors that make stubborn fat stubborn). But people needn't be worrying about stubborn fat until they're pretty lean. The amount of loss or gain will always be determined by energy balance.
In the real world, I think fasts push some people into binge cycles or disordered eating. For others, it works really well with their lifestyle and apetite.12 -
I do two fasts a month now. These are liquid fasts that consist of natural juices, broth and such. I have to be careful to get enough variety and I take vitamins also. I do this for no more than two days. I concentrate better. I sleep great when I do this and I don't know why!? I get rid of a lot of water retention too. Hope this helps me lose faster.3
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Here is a thought. While fasting your insulin goes down to your fasting level. (Unless you are type 1 diabetic you always have some insulin in your blood.) The lower this level the easier it is for your body to use fat stores. By increasing the hours without comsumig food, maybe the fasting insulin goes lower over time allowing for more fat to be used.
Anyway that seems to be a common claim.
I think this can be helpful in mobilizing stubborn fat (fasting can inhibit the alpha-2 receptors that make stubborn fat stubborn). But people needn't be worrying about stubborn fat until they're pretty lean. The amount of loss or gain will always be determined by energy balance.
In the real world, I think fasts push some people into binge cycles or disordered eating. For others, it works really well with their lifestyle and apetite.
I completely agree if fasting pushes one into an eating disorder then it is a horrible idea. I think a part of fasting is being in control of what you eat and when you eat. That might be too idealistic but I think there should be a mindfulness about it. For example after I fasted, I tried to replace the missed calories with foods like walnuts to shore up areas that were weak in my diet.
I have more extreme views on energy balance so I don't want to derail things. While at some point there is an energy balance, I just believe how that balance is maintained can vary a lot. I'm trying to learn more about fasting to see if it might actually help keep the body shifted towards burning fat to meet a energy deficit rather than storing fat and reducing metabolism to handle an even larger energy deficit. In that end I'm experimenting a bit with fasting, but I will have a major travel disruption this month so it is a good time for me to also learn and think about what to do.0 -
OneWayOnly1912 wrote: »I do two fasts a month now. These are liquid fasts that consist of natural juices, broth and such. I have to be careful to get enough variety and I take vitamins also. I do this for no more than two days. I concentrate better. I sleep great when I do this and I don't know why!? I get rid of a lot of water retention too. Hope this helps me lose faster.
There seems to be big difference in fasting that kicks in around the 3 day mark which results in at least a temporary lower metabolism. I don't know that from experience only from reading. Before that there is some studies that show modest increases in metabolism. Still 2 days, twice a month sounds like a pretty major commitment. It is good to hear of your positive results.0 -
I am no real authority on fasting, so I shouldn't really be commenting, I suppose, but my personal take on fasting is not so positive. I need protein to stay full and not get hangry. I have personally found that simply dropping my sugar intake to a certain bare minimum, doing strength training, logging my food intake and making sure I eat foods that help build muscle and burn fat is what helps me burn the fat, eventually.
My personal gut reaction to someone recommending that I fast for weight loss is this: "are you kidding me?"
Now, this said, I have heard that a juice-based detox helps get rid of the toxins that keep fat in your body. This I might try, but only for maybe half a day, or as a continual post-workout recovery thing over the course of a week or two. But I've tried doing the fasting thing, and it did not make me a happy camper in the least.
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What you're talking about is basically intermittent fasting or IF. Some people have an "eating window" where they only eat during a predetermined time frame (16:8 where you fast 16 hrs and eat during an 8 hr window, etc). Other people do 5:2 where they eat 500 calories 2 days a week and eat at maintenance the other 5 days (that's what I do). I like it, but it's not for everyone. It's really just another way of creating a weekly calorie deficit.
http://community.myfitnesspal.com/en/group/100058-5-2-fasting6 -
I realize that a lot of people use intermittent fasting to create calorie deficit. I think there are easier ways to do that though. I'm interested in the benefits past than and I'll check out the 5-2-fasting thread. Frankly I think fasting for full days is a lot harder than just skipping a meal.1
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What you're talking about is basically intermittent fasting or IF. Some people have an "eating window" where they only eat during a predetermined time frame (16:8 where you fast 16 hrs and eat during an 8 hr window, etc). Other people do 5:2 where they eat 500 calories 2 days a week and eat at maintenance the other 5 days (that's what I do). I like it, but it's not for everyone. It's really just another way of creating a weekly calorie deficit.
http://community.myfitnesspal.com/en/group/100058-5-2-fasting
Wow, I didn't even know about the groups. Thanks!1 -
I don't think it would be harmful, but I doubt it would help. I just don't see how that makes sense -- your body is going to need and use what it does to run and fuel movement, no matter what.
I've fasted for religious purposes and don't find a one day full fast difficult, and don't find the eating window thing difficult either, although it doesn't appeal to me (snacking within a window would be less effective for me than just not snacking and eating regular meals).
I like the idea of 5:2 IF, and don't think 2 low cal days would be tough or that I would make up the calories (I have found I have low cal weeks in weeks with fast days even if I don't restrict -- I never make up the calories lost on Good Friday on Easter, for example, even though I am not doing that for dieting purposes). What has seemed a stumbling block to me is that if I exercise fasted I tend to be really hungry and feel like eating later in the day in a way that makes me think I can't exercise on the low cal days in 5:2, and I also am concerned about being able to keep protein up (which would be my personal difficulty if I did a plan that involved an eating window/skipping one of my 3 regular meals, too).
For me this isn't a debate topic, although one I am interested in because I've been thinking off and on about trying IF.1 -
That is an interesting thing about fasting it has been around for a very long time. I've never fasted for religious reasons, but I was aware of it. I have heard of people that did fast one day a week, a couple at least. Neither were thin but they weren't fat either.
There are a lot of claims about fasting both pro and con. However I'm not pretty sure that fasts less than a day are harmless. I haven't noticed any difference in my conditioning but did lose a little more but that might have just been luck.
I also noticed my hunger was greater than normal after I exercised in the fasted state. Normally I don't feel hungry after exercise for at least and hour or two.2 -
Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.7 -
The body will only be affected by a fast after 2-3 days. So other then messing with your weekly calorie goal, it doesn't do anything useful. In fact it probably does more harm then good because you don't get the nutrients you need for the day.1
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Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.0 -
or you can just eat in a consistent calorie deficit and you will lose fat that way ...5
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Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. 1) This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
2) Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.
1) This is an example of a disease affecting the CO side of CICO. When Type 2 diabetics gain weight, it is because their CO is less than their CI. The fact that hormonal problems can affect CO doesn't mean that they are gaining weight while in a calorie deficit.
2) This is an example of the reverse, where a disease is affecting the CI side of CICO. When the body is unable to process the food taken in (as in the example you give), the CI will be affected and potentially create a calorie deficit. This does not mean that you can lose weight while in a calorie surplus. It means that there are diseases that can cause the surplus to not occur.
Healthy people don't have these problems so I don't see how fixing these problems (if IF is even effective in managing these problems in humans) could be a "huge benefit" to them.12 -
Carlos_421 wrote: »Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. 1) This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
2) Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.
1) This is an example of a disease affecting the CO side of CICO. When Type 2 diabetics gain weight, it is because their CO is less than their CI. The fact that hormonal problems can affect CO doesn't mean that they are gaining weight while in a calorie deficit.
2) This is an example of the reverse, where a disease is affecting the CI side of CICO. When the body is unable to process the food taken in (as in the example you give), the CI will be affected and potentially create a calorie deficit. This does not mean that you can lose weight while in a calorie surplus. It means that there are diseases that can cause the surplus to not occur.
Healthy people don't have these problems so I don't see how fixing these problems (if IF is even effective in managing these problems in humans) could be a "huge benefit" to them.
which does not change the fundamental truth of CICO, except that certain people need medication to regulate the out side of CICO, so it is still CICO...
5 -
Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
If they just ate a "normal" meal and then fasted for 16 hours, I would think it pretty likely the individual would have a pretty low calorie intake which would obviously result in burning fat to make up for the energy deficiency.3 -
cwolfman13 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
If they just ate a "normal" meal and then fasted for 16 hours, I would think it pretty likely the individual would have a pretty low calorie intake which would obviously result in burning fat to make up for the energy deficiency.
I've read one of the books about 5:2, and the author (who has done studies on the supposed benefits of the fasting periods) attributes the weight loss, at least in large part, to the calorie deficit. According to her, if someone has a low calorie day they tend to (on average) eat more than maintenance the next day, but not enough more to blot out the overall deficit for the week. (This is borne out for me by my own experiences, as I said.)
That aside, many who do the diet tend to track non fasting days as well as fasting to stay at maintenance, which ensures a deficit.
With the windows I think it's pretty clear that for many who do them at least they create a deficit, especially in the short term. There's a limit to how much most want to eat at a time, especially if they mostly stick to their normal diets and don't go nuts on restaurant food or some such.1 -
cwolfman13 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
If they just ate a "normal" meal and then fasted for 16 hours, I would think it pretty likely the individual would have a pretty low calorie intake which would obviously result in burning fat to make up for the energy deficiency.
so in other words, just another fancy way to create a calorie deficit...0 -
I lost the majority of my weight doing Alternate day Fasting.
Monday-500 calories
Tuesday-TDEE
Wednesday-500 calories
Thursday-TDEE and so on.
When i first started i found it easier to diet every second, rather than 7 days a week.
ETA: It was a 24 hour fast from dinner till dinner the next night.2 -
lemurcat12 wrote: »cwolfman13 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
If they just ate a "normal" meal and then fasted for 16 hours, I would think it pretty likely the individual would have a pretty low calorie intake which would obviously result in burning fat to make up for the energy deficiency.
I've read one of the books about 5:2, and the author (who has done studies on the supposed benefits of the fasting periods) attributes the weight loss, at least in large part, to the calorie deficit. According to her, if someone has a low calorie day they tend to (on average) eat more than maintenance the next day, but not enough more to blot out the overall deficit for the week. (This is borne out for me by my own experiences, as I said.)
That aside, many who do the diet tend to track non fasting days as well as fasting to stay at maintenance, which ensures a deficit.
With the windows I think it's pretty clear that for many who do them at least they create a deficit, especially in the short term. There's a limit to how much most want to eat at a time, especially if they mostly stick to their normal diets and don't go nuts on restaurant food or some such.
I do agree that many use fasting so they don't have to count calories and it is easier to have a calorie deficit. I have also read many examples of what you talked about that even though people eat more on non-fast days they still end up with a weekly calorie deficit.
Still I'm really interested in the non-calorie deficit benefits or issues. Clearly most people are healthy enough to not really suffer much from missing a meal or two, however do they gain back anything from doing so?
* One such benefit I've been reading about is a slight metabolic increase although one might have to fast for more than 20 hours for that to happen and if you fast too long your metabolism probably decreases.
* Another claim is repeated fasting puts pressure on the fasting insulin level and helps lower it over time. Since insulin is a primary gate keeper when it comes to burning or storing fat, lower fasting levels of insulin are better for burning fat.
* Other claims would be harder to measure like improved mental state and so forth.0 -
Carlos_421 wrote: »Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. 1) This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
2) Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.
1) This is an example of a disease affecting the CO side of CICO. When Type 2 diabetics gain weight, it is because their CO is less than their CI. The fact that hormonal problems can affect CO doesn't mean that they are gaining weight while in a calorie deficit.
2) This is an example of the reverse, where a disease is affecting the CI side of CICO. When the body is unable to process the food taken in (as in the example you give), the CI will be affected and potentially create a calorie deficit. This does not mean that you can lose weight while in a calorie surplus. It means that there are diseases that can cause the surplus to not occur.
Healthy people don't have these problems so I don't see how fixing these problems (if IF is even effective in managing these problems in humans) could be a "huge benefit" to them.
which does not change the fundamental truth of CICO, except that certain people need medication to regulate the out side of CICO, so it is still CICO...
With diabetics, insulin is already the medicine. The body often adjusts by changing metabolism, meaning that CO = f(CI). Sometime fat stores are not accessible for energy because of insulin levels.
Insulin resistance is the first stage of these problems and current estimates run as high as 60% of the US population being insulin resistant. That level is highly debatable, but it is clearly much higher now than it was a few decades ago. This is a rapidly spreading problem world wide. Being insulin resistant means one is not healthy and that their metabolism is working against them when it comes to burning fat because of too much insulin in the blood.
Fasting might be a way to help allow the body to recover from insulin resistance. There are a few doctors that make those kinds of claims. However insulin levels can't be measure with simple home blood tests, at least yet so it is difficult to personally identify.3 -
Carlos_421 wrote: »Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. 1) This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
2) Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.
1) This is an example of a disease affecting the CO side of CICO. When Type 2 diabetics gain weight, it is because their CO is less than their CI. The fact that hormonal problems can affect CO doesn't mean that they are gaining weight while in a calorie deficit.
2) This is an example of the reverse, where a disease is affecting the CI side of CICO. When the body is unable to process the food taken in (as in the example you give), the CI will be affected and potentially create a calorie deficit. This does not mean that you can lose weight while in a calorie surplus. It means that there are diseases that can cause the surplus to not occur.
Healthy people don't have these problems so I don't see how fixing these problems (if IF is even effective in managing these problems in humans) could be a "huge benefit" to them.
You admit there are things thing modify CI & CO. In fact I only gave two simple examples there are dozens to hundreds of other modifiers. The human body isn't a simple closed system and food is used for a lot more than just providing energy. The overwhelming evidence is that most diets fail. If it was simple then that wouldn't be the case.
I understand your concerns about IF. I was of the same mindset a few months ago. Even though I've been doing some short fasts with positive results, I haven't made up my mine yet.1 -
So another common claim is with short fasts there is more human growth hormone production. That helps with building muscles and it is also a hormone that helps burn fat.
I have a elbow that is still healing from am injury, but I think as it gets better and I go back to building up my pull ups, I'll just have to try a few weeks of IF to see if it makes a difference will building strength up. Those are painful workouts that typically cause a lot of DOMS in the chest, shoulders, back and parts of the arms. They also hard on the hands but hanging from bars builds an insane amount of hand strength. At least I'm pretty convinced now that there isn't any harm from short fasts.0 -
Carlos_421 wrote: »Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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 assume people eat just as many calories weather they fast or not. It wouldn't be about energy balance it is about what source of energy the body will use.
You assume incorrectly.
The point of intermittent fasting is that it makes it easier for some people to adhere to a calorie deficit because fitting TDEE-500 into a four hour window makes for much larger meals than spreading out the same intake across the entire day.
All the potential hormonal benefits are fine and dandy but regardless of what your insulin levels do, you will not lose fat if you eat as much as you burn and you will lose fat if you eat less than you burn no matter whether you eat all day or only for four hours.
It is quite possible to gain fat even while eating at a calorie deficit. 1) This can happen with type 2 diabetics when they are put on insulin. Fat gets created and the metabolism is slowed down even more to make up the difference causing the person to feel lousy. That is one of the reasons that T2D is a progressive disease. While there is energy balance it isn't always simple or even something we can control. https://www.drugs.com/sfx/insulin-side-effects.html
2) Type 1 diabetics actually lose weight no matter how much they eat when their insulin is too low. They can gorge themselves and they literally die of starvation without insulin.
Potentially if fasting helps reset fix hormonal problems it could be a huge benefit even to relatively healthy people. However at this point it appears most studies are animal based. There is probably more information that I'm not aware of it.
1) This is an example of a disease affecting the CO side of CICO. When Type 2 diabetics gain weight, it is because their CO is less than their CI. The fact that hormonal problems can affect CO doesn't mean that they are gaining weight while in a calorie deficit.
2) This is an example of the reverse, where a disease is affecting the CI side of CICO. When the body is unable to process the food taken in (as in the example you give), the CI will be affected and potentially create a calorie deficit. This does not mean that you can lose weight while in a calorie surplus. It means that there are diseases that can cause the surplus to not occur.
Healthy people don't have these problems so I don't see how fixing these problems (if IF is even effective in managing these problems in humans) could be a "huge benefit" to them.
You admit there are things thing modify CI & CO. In fact I only gave two simple examples there are dozens to hundreds of other modifiers. The human body isn't a simple closed system and food is used for a lot more than just providing energy. The overwhelming evidence is that most diets fail. If it was simple then that wouldn't be the case.
I understand your concerns about IF. I was of the same mindset a few months ago. Even though I've been doing some short fasts with positive results, I haven't made up my mine yet.
I never contested that there are things that modify CI and CO. That was never put up for debate.
You claimed that it's possible to gain fat while eating in a calorie deficit. This is absolutely false and the very fact that CI and CO can be modified is what explains away your examples.
Where you say that people are gaining fat in a deficit, I say the deficit didn't exist due to the factors affecting CO.8 -
Not all measurable effects, but I love what I have experienced since starting 18:6. I feel "ON". Clear-headed. Not hungry. No cravings. My blood pressure dropped to normal for the first time since I was a teenager. It had been in the 130/90s for several weeks after I lost weight, but only dropped into normal range after a few weeks of IF and maintaining weight. Maintaining a calorie target is a breeze. I'm not even logging anymore. It is easy to eat two ~700-calorie meals without measuring everything. Can you tell I'm a fan?
As far as the original question of whether or not it helps to burn fat, it makes sense to me that exercising while fasted, with very low levels of insulin and glycogen stores running out, would make more fat be utilized for energy.
Another great benefit is autophagy. Dr. Fung's website has a ton of stuff on the benefits of fasting. Here's the page on autophagy: https://intensivedietarymanagement.com/fasting-and-autophagy-fasting-25/
3 -
CorneliusPhoton wrote: »Not all measurable effects, but I love what I have experienced since starting 18:6. I feel "ON". Clear-headed. Not hungry. No cravings. My blood pressure dropped to normal for the first time since I was a teenager. It had been in the 130/90s for several weeks after I lost weight, but only dropped into normal range after a few weeks of IF and maintaining weight. Maintaining a calorie target is a breeze. I'm not even logging anymore. It is easy to eat two ~700-calorie meals without measuring everything. Can you tell I'm a fan?
As far as the original question of whether or not it helps to burn fat, it makes sense to me that exercising while fasted, with very low levels of insulin and glycogen stores running out, would make more fat be utilized for energy.
Another great benefit is autophagy. Dr. Fung's website has a ton of stuff on the benefits of fasting. Here's the page on autophagy: https://intensivedietarymanagement.com/fasting-and-autophagy-fasting-25/
I'm a big fan also and can report similar positive effects.
I've bookmarked that autophargy blog post for future reading - Thanks for that I've been looking for something on that subject for a while.
With respect to fat usage in fasted exercise, I don't think the evidence points to that. During a recent post on another MFP thread I did a little bit of googling on google scholar and pulled up this 2011 paper:
https://www.researchgate.net/profile/Antonio_Paoli/publication/50409403_Exercising_fasting_or_fed_to_enhance_fat_loss_Influence_of_food_intake_on_respiratory_ratio_and_excess_postexercise_oxygen_consumption_after_a_bout_of_endurance_training/links/0912f502eba1356566000000.pdf
"The authors conclude that when moderate endurance exercise is done to lose body fat,
fasting before exercise does not enhance lipid utilization; rather, physical activity after a light meal is advisable."
It's a small study but it's the only one I've seen (I'm no expert on this subject, but keen to learn) where fasted exercise was compared to fed, iso-colorifically in humans.2
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