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Are short fasts really helpful for burning fat?
Replies
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There are many variables and many possible outcomes but typically only about 5% are successful with losing fat and keeping it off. As for the glycogen depletion, very few people actually can actually burn so much glycogen that it can't be replaced from the food being consumed. It is really very difficult to just exercise yourself slim.
Intermittent fasting though would help a lot by helping making it easier to deplete more glycogen and providing periods where blood glucose and insulin are lower. People aren't successful with burning fat if insulin levels are too high. It is likely that most people are in that state most of the waking hours. If those people eat a calorie deficit they end up feeling horrible because the body reduces energy expenditure if it can burn enough fat.
Do you know that the human body has a very limited ability to store glycogen? A typical athletic male can hold about 2,500 calories of it. And no more. You don't use up all the glycogen in your body and become slender as a result.0 -
I recently started an 16:8 plan and I love it! I was already restricting to between 1200 and 1400 calories a day for weight loss and that hasn't changed. But since I started I have so much more energy and it's much easier to stay within my calorie range.1
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Science_101 wrote: »Carlos_421 wrote: »Well it depends. Is that lunch 2000 calories?
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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.
No, no one can gain weight in a deficit. Sure it has been a few years since I had basic physiology and physics, but what you are literally claiming is that energy (fat) can be created from nothing. That would make a person a perpetual motion/energy machine. If this is true they why are we not harvesting diabetics and/or using insulin to power our infrastructure instead of using our limited natural resources?
So, instead of sending fat people to the camps, we should be harvesting them, Matrix style? It's genius!1 -
The poster is misunderstanding the link about insulin. It's true that weight loss is a common side effect of diabetes and that someone who lacks insulin will likely gain when insulin is available -- that's because in the absence of insulin (or the ability to use insulin properly) you will have trouble putting on fat and can't use calories efficiently. The link explains the weight gain as due to calories being used more efficiently, so the person having to adjust to what was likely overeating before. Not a claim that being diabetic makes you gain despite a deficit.
This supports my point above that being IR wouldn't make you fat (absent excess calories), and instead is a common side effect of being obese for those with a propensity (not everyone IR is obese, of course, but it's a huge risk factor).
Again, I see in this common misreading an effort to claim that you can become obese/overweight without overeating, and that's not so. (One can have a thyroid issue that makes overeating happen at a ridiculously low level and needs to be corrected, but that's not what's happening with the typical T2D who is obese and doesn't also have preexisting thyroid issues.)2 -
lemurcat12 wrote: »The poster is misunderstanding the link about insulin. It's true that weight loss is a common side effect of diabetes and that someone who lacks insulin will likely gain when insulin is available -- that's because in the absence of insulin (or the ability to use insulin properly) you will have trouble putting on fat and can't use calories efficiently. The link explains the weight gain as due to calories being used more efficiently, so the person having to adjust to what was likely overeating before. Not a claim that being diabetic makes you gain despite a deficit.
This supports my point above that being IR wouldn't make you fat (absent excess calories), and instead is a common side effect of being obese for those with a propensity (not everyone IR is obese, of course, but it's a huge risk factor).
Again, I see in this common misreading an effort to claim that you can become obese/overweight without overeating, and that's not so. (One can have a thyroid issue that makes overeating happen at a ridiculously low level and needs to be corrected, but that's not what's happening with the typical T2D who is obese and doesn't also have preexisting thyroid issues.)
It seem that you are assuming your body can't make other changes to compensate for the food or lack of food it is getting. When we eat less our bodies can do a lot to keep us living in a lower calorie budget. When we eat more our bodies can also do a lot to help burn the excess calories. So it can turn out that what should be a calorie deficit is really a calorie surplus, that is even more likely in people that are insulin resistant because they will have even more insulin in the blood than a non-insulin resistive person.
This problem is compounded because it isn't easy to measure how much insulin is in the blood. Measuring glucose isn't hard but that is only part of the story. The problem is if you have too much insulin and it is pushing the glucose into cells including fat cells then the body can make up the difference by lowering metabolism in a variety of ways. The fundamental problem is you can't know that you are in a calorie deficit until weigh has been actually lost.
Overeating is just part of the problem. While there are obese people that eat enough for multiple people there are also obese people that don't really eat as much food as many normal people. It isn't often just about the food consumed.
Still I'm not sure is fasting will really cure insulin resistance, or if it does how long of a fast it would take.
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Before flying to the US on Aug. 10th I fasted for about 28 hours and then started eating in the US time zone. (I probably over ate a bit.) The fasting wasn't that hard. However I don't think the fasting is having a positive impact on my blood glucose levels yet. My fasting glucose is just over normal and it is the same as it was five years ago. However I've done only about 1/2 dozen fasts so far.
My 28 hour fast seemed to really help with adjusting to the US time. I was even able to drive 700 miles on my first full day in the states, although I was tired after that.0 -
It helps if it helps you eat less. Other than that no, because if you break your fast with over 9000 calories you're still going to gain weight.
However, I have noticed other benefits such as mental clarity during the fasted periods. I don't worry about what I'm gonna have for lunch during work. I spend a lot less on food and when I finally do eat my food tastes DAMN good.1 -
Are you intending to debate between the link of fasting with people with IR issues or without? There is some evidence that fasting is beneficial in those with IR, but not so much in individual without IR issue.
Also, to point out, even with very low levels of insulin, you can still gain weight. There is more than one anabolic hormone besides insulin. Just look up Acylation Stimulating Protein and Glucose-dependent Insulinothropic Peptide.
It seems you only discuss the negative of insulin, but you should also know that it stimulates muscle protein synthesis and other hormones to build muscle. So if your goal is solid body composition during a cut, you should have a training program to support that, including nutrition to support muscle growth or even muscle sustainment.3 -
Are you intending to debate between the link of fasting with people with IR issues or without? There is some evidence that fasting is beneficial in those with IR, but not so much in individual without IR issue.
Also, to point out, even with very low levels of insulin, you can still gain weight. There is more than one anabolic hormone besides insulin. Just look up Acylation Stimulating Protein and Glucose-dependent Insulinothropic Peptide.
It seems you only discuss the negative of insulin, but you should also know that it stimulates muscle protein synthesis and other hormones to build muscle. So if your goal is solid body composition during a cut, you should have a training program to support that, including nutrition to support muscle growth or even muscle sustainment.
Yes insulin has gotten a bad rap. I think what people most of the time miss is that it's not elevated insulin that has to be looked out for, but chronically elevated insulin.
IMO, it boils down to a basic misunderstanding of human physiology and majoring in the minors...7 -
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.
To address this.
In a standard eating pattern your body will cycle between lipolysis and lipogenesis, depending on when you eat a meal. So you eat foods, your body breaks down the nutrients, insulin and ASP upregalate, inhibits HSL and lipogenesis occur. After insulin downregulates BG, your body will be able to enter lipolysis, and HSL will not be suppressed.
If you modify this eating pattern, to have 1 or 2 meals (pending calories are equal), your body will have longer periods in those areas for digestion and increase insulin/ASP/GIP during those periods. Essentially, you are going from 3 small mountains to 1 or 2 larger mountains.3 -
I am a diabetic so I find it impossible to fast. But it is taking me a long time to find some healthy snacks to curb my appetite. Waiting too long to eat just makes me eat more. And if I fasted I might as well just pull a chair up to the refrigerator when the fast is over0
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Are you intending to debate between the link of fasting with people with IR issues or without? There is some evidence that fasting is beneficial in those with IR, but not so much in individual without IR issue.
Also, to point out, even with very low levels of insulin, you can still gain weight. There is more than one anabolic hormone besides insulin. Just look up Acylation Stimulating Protein and Glucose-dependent Insulinothropic Peptide.
It seems you only discuss the negative of insulin, but you should also know that it stimulates muscle protein synthesis and other hormones to build muscle. So if your goal is solid body composition during a cut, you should have a training program to support that, including nutrition to support muscle growth or even muscle sustainment.
Yes insulin has gotten a bad rap. I think what people most of the time miss is that it's not elevated insulin that has to be looked out for, but chronically elevated insulin.
IMO, it boils down to a basic misunderstanding of human physiology and majoring in the minors...
Yes, chronically elevated insulin is a much better description.
The problem though is insulin isn't easy to measure and it is probably even harder to verify insulin resistance. Those require medical lab tests and probably a doctor to help with. So there is a good amount of estimation with what is really going on.
Blood glucose is easy to measure though, so maybe that is something I should focus on more. While it doesn't tell one how much insulin is required to manage the blood sugar, it does give an indication of how well your body is managing blood sugar. If it blood glucose tends to be higher than it should be, it probably does mean there is some insulin resistance.0 -
I am a diabetic so I find it impossible to fast. But it is taking me a long time to find some healthy snacks to curb my appetite. Waiting too long to eat just makes me eat more. And if I fasted I might as well just pull a chair up to the refrigerator when the fast is over
Well I'm not a doctor but there are a few doctors using fasting with type 2 diabetics to cure their patients. I'm sure that type of fasting should only be done under a doctor's supervision and it probably isn't for everyone. https://intensivedietarymanagement.com/category/patient-testimonials/
Some of those fasts used were very extreme, not even close to what I would consider a short fast.0 -
Are you intending to debate between the link of fasting with people with IR issues or without? There is some evidence that fasting is beneficial in those with IR, but not so much in individual without IR issue.
Also, to point out, even with very low levels of insulin, you can still gain weight. There is more than one anabolic hormone besides insulin. Just look up Acylation Stimulating Protein and Glucose-dependent Insulinothropic Peptide.
It seems you only discuss the negative of insulin, but you should also know that it stimulates muscle protein synthesis and other hormones to build muscle. So if your goal is solid body composition during a cut, you should have a training program to support that, including nutrition to support muscle growth or even muscle sustainment.
I absolutely agree, insulin is only part of the story. With IR people have consistently too much insulin which is a different problem that more normal levels of insulin. As you point out, normal levels of insulin is beneficial and even necessary to good health.
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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.
To address this.
In a standard eating pattern your body will cycle between lipolysis and lipogenesis, depending on when you eat a meal. So you eat foods, your body breaks down the nutrients, insulin and ASP upregalate, inhibits HSL and lipogenesis occur. After insulin downregulates BG, your body will be able to enter lipolysis, and HSL will not be suppressed.
If you modify this eating pattern, to have 1 or 2 meals (pending calories are equal), your body will have longer periods in those areas for digestion and increase insulin/ASP/GIP during those periods. Essentially, you are going from 3 small mountains to 1 or 2 larger mountains.
As far as fat loss goes, I'm finding that lower levels of exercise seem to be causing me to burn more fat when that exercise is done in the fasted state vs doing much harder exercise in the non-fasted state. Sometimes I skip supper and that does seem to enhance the fat lost.
As far as building muscle I'm unsure. I have an elbow injury that is limited my upper body workouts right now. Well I don't seem to be losing any muscle mass, I'm clearly not building a large amount right now. While my running while fasted has been improving a lot, it is still below my bests. However, running isn't really strength related and it doesn't promote much muscle gains.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.
To address this.
In a standard eating pattern your body will cycle between lipolysis and lipogenesis, depending on when you eat a meal. So you eat foods, your body breaks down the nutrients, insulin and ASP upregalate, inhibits HSL and lipogenesis occur. After insulin downregulates BG, your body will be able to enter lipolysis, and HSL will not be suppressed.
If you modify this eating pattern, to have 1 or 2 meals (pending calories are equal), your body will have longer periods in those areas for digestion and increase insulin/ASP/GIP during those periods. Essentially, you are going from 3 small mountains to 1 or 2 larger mountains.
As far as fat loss goes, I'm finding that lower levels of exercise seem to be causing me to burn more fat when that exercise is done in the fasted state vs doing much harder exercise in the non-fasted state. Sometimes I skip supper and that does seem to enhance the fat lost.
As far as building muscle I'm unsure. I have an elbow injury that is limited my upper body workouts right now. Well I don't seem to be losing any muscle mass, I'm clearly not building a large amount right now. While my running while fasted has been improving a lot, it is still below my bests. However, running isn't really strength related and it doesn't promote much muscle gains.
One would not really be able to tell if they lost muscle or not. In all reality, loss of lean body mass (more than just muscle) is inevitable during weight loss. And if one is not resistance training (LISS is not resistance training) and eating adequate protein (~.8 to 1g per lb of lean body mass during an energy deficiency), then you will have a greater chance of not only losing lean body mass, but muscle as part of that.
I suspect that since you are skipping dinner, even occasionally, and reduced exercise (which can also reduce hunger induced by hard exercise), I would fully suspect that this approach as made it easier for you to sustain a deficit. Just make sure you aren't averaging several pounds a week, especially as you get lean; I would also recommend, higher levels of protein.
Unfortunately, many people tend to be very short sighted when it comes to their goals. More often than not, do people only look at weight loss as a goal. Not until they are within a normal range do they think of what is next. Ideally, your dietary approach should not only address your medical requirements (if any), but also your end state goals.
As an aside, I did 16:8 for several month until I had to give it up. I never seemed to get passed the crazy hunger and bad breath. I have found that 3 big meals are much better towards my eating needs. I also noticed that I didn't see any increased fat loss or better results as compared to a traditional 3 meal approach per day. But one thing I did learn... there is no way in hell I can workout fasted. Holy crap on a cracker did that almost kill me.0 -
I started working out before breakfast (in a fasted state) because of time pressures. I took a major hit in my performance but over the past few months that gap has been closing and I'm slowly starting to do HIIT and even work in resistance training. It is easy to believe that working out hard in a fasted state would be difficult. Since I mostly do body weight calisthenics for resistance it is easy to slip some of that in later in the day.
As far as lean body weight, it isn't that hard to estimate. You don't know to the gram, but one can tell if they are gaining or losing ground. I did have a DEXA scan and it turned out my estimates weren't bad, maybe a little low for lean body mass. For body fat I was mostly use BIA scale and had estimated my total body fat at 24.5%. The DEXA scan measured 24.1% for total body fat. Anyway a good BF measurement makes it pretty easy to see if one is gaining or losing lean body mass.
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I made the best progress after I had adopted an intermittant fasting style of eating. I still chose vegetable and lean meat heavy meals, but they were condensed into the span of 4-6 hours instead of 12 (or more). I would wait to eat until lunchtime and I loved having a big bowl of braised greens, fried eggs, and roasted sweet potatoes. The meal was larger and more caloric than a typical "diet" meal and left me so satisfied. I would have a healthy snack in the afternoon and eat my last meal, with dessert if I wanted at around 5, no eating past 6. I didn't count calories every day because I think it's a pain. Yes, if you have the right food personality IF works well!2
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I'm finding skipping dinner sometimes to be working well. Pushing three meals into two isn't much of a sacrifice. Short term though I've lost too much weight too fast. Now I need to just try and hold the weight loss.1
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