HELP ME UNDERSTAND!!!
simply_bubbz
Posts: 245 Member
So I keep hearing about how when your glycogen is depleted that's when your fat stores are getting burned or whatever....so what about when our glycogen is up which is most ppl who eat carbs on a regular but are still on a deficit..then what are they burning? if they don't deplete their glycogen then how are they losing weight if they're fat stores aren't burning b/c their glycogen is up? please someone explain this to me in simple terms.
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Glycogen is how the body stores carbohydrate. The body uses it along with stored fat as a source of energy. Depleting your glycogen stores is not necessary for losing weight. But people who do ketogenic diets look to do this to get them into ketosis. But again, not necessary for weight loss.
right and when I ask them why do they want to go into ketosis they say it's because fat is burned faster. so is that what happens?0 -
you can lose weight either way but depleting your glycogen means burning fat faster?0
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It's just different energy sources the body accesses primarily. So carb diets turn to glycogen, keto/low carb turn to fat. Both are replenished when we eat. If we eat in a deficit then there will be a reduction of body fat regardless of way of eating.1
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simply_bubbz wrote: »Glycogen is how the body stores carbohydrate. The body uses it along with stored fat as a source of energy. Depleting your glycogen stores is not necessary for losing weight. But people who do ketogenic diets look to do this to get them into ketosis. But again, not necessary for weight loss.
right and when I ask them why do they want to go into ketosis they say it's because fat is burned faster. so is that what happens?
No, body fat is not burned faster in ketosis. In ketosis the body does burn more fat, but it's dietary fat combined with body fat. The body fat loss will be equal to that of a person eating carbs if the deficit was the same. I might murder people if I had to cut carbs to lose weight.9 -
Your fat stores are always being burned. As you increase the intensity of aerobic exercise, the percentage of energy that comes from blood glucose and stored glycogen increases, but you're also metabolizing fat. It's just that there's a limit to how much fat you can burn at a time. There's some evidence that you can increase the percentage of fat burned during moderate aerobic exercise by "training low" carb, i.e. exercising hard in the evening, eating a low-carb meal (so as not to restore glycogen), and then exercising again in the morning before breakfast, so that your stored glycogen is really low. Unless you're training for ultraendurance activities in the boonies, though, that's not necessary, and it's not a lot of fun either.
However, the specifics of where energy comes from at any given moment don't matter. Your body is always rebalancing energy depending on your immediate needs: storing glycogen or expending it, storing excess as fat or releasing free fatty acids, using protein to repair cells, etc. All that matters is the balance at the end of the day. If you expend 500 calories more a day than you take in, that energy has to come from muscle or fat stores. If you lift weights or do other resistance exercise (e.g. a bodyweight routine), you'll minimize muscle loss and maximize fat loss.5 -
It is true to say that regardless of what you're eating (carbs vs fat) if you are experiencing a caloric deficit, you will lose weight. That said, adjusting to ketosis (adjusting to a low carb diet) "tunes" your body to burn fat. In the developed world we are inundated with limitless carbohydrates from birth, so it's no surprise that our bodies adapt to running on carbs. A side effect is that we get worse at processing fats to expend as energy (dietary or from stores). Going on a low carb diet forces the body to acclimate to fats as a fuel. To be briefly technical, the acclimation comes in the form of the livers ability to convert fat to ketones, and it makes genes used solely for fat metabolism more likely to be transcribed.
You burn fat when carbs have run out. Most non-keto-adapted people describe that as "the wall." Meaning it's a barrier that's hard to surpass. It's hard to surpass because your body is not ready to use the other fuel (fat). While you may lose the same amount of weight on a carb vs low carb diet if they have the same deficit, being adapted to fats makes it easier to increase the deficit. "The wall" is much easier to pass in your workout once keto-adapted. That being said, becoming keto-adapted is very difficult. Too difficult to be worthwhile for some people; some would rather just fight through "the wall" every work out session; to each his own.2 -
DShaull315 wrote: »It is true to say that regardless of what you're eating (carbs vs fat) if you are experiencing a caloric deficit, you will lose weight. That said, adjusting to ketosis (adjusting to a low carb diet) "tunes" your body to burn fat. In the developed world we are inundated with limitless carbohydrates from birth, so it's no surprise that our bodies adapt to running on carbs. A side effect is that we get worse at processing fats to expend as energy (dietary or from stores). Going on a low carb diet forces the body to acclimate to fats as a fuel. To be briefly technical, the acclimation comes in the form of the livers ability to convert fat to ketones, and it makes genes used solely for fat metabolism more likely to be transcribed.
You burn fat when carbs have run out. Most non-keto-adapted people describe that as "the wall." Meaning it's a barrier that's hard to surpass. It's hard to surpass because your body is not ready to use the other fuel (fat). While you may lose the same amount of weight on a carb vs low carb diet if they have the same deficit, being adapted to fats makes it easier to increase the deficit. "The wall" is much easier to pass in your workout once keto-adapted. That being said, becoming keto-adapted is very difficult. Too difficult to be worthwhile for some people; some would rather just fight through "the wall" every work out session; to each his own.
I hear it said a lot from the keto crowd that our bodies are bad at burning fat, but I don't know that I have ever seen science showing this. I also wouldn't say we eat limitless carbohydrates from birth, I've never seen a diet that consists of 100% carbs.5 -
I think most people will know that when I say limitless I don't mean 100%. It's in reference to the fact that in our evolutionary history we would have needed to go without carbs for periods of time, and in our current civilizations we never have to.0
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DShaull315 wrote: »I think most people will know that when I say limitless I don't mean 100%. It's in reference to the fact that in our evolutionary history we would have needed to go without carbs for periods of time, and in our current civilizations we never have to.
In history we likely did have to go without carbs for periods of time. We also had to go without eating too. Our bodies got really good at figuring out how to reduce our energy expenditure when calories started dwindling. It's not that our bodies are bad at burning fats or that our bodies get better at it when we cut out carbs.4 -
DShaull315 wrote: »You burn fat when carbs have run out. Most non-keto-adapted people describe that as "the wall." Meaning it's a barrier that's hard to surpass. It's hard to surpass because your body is not ready to use the other fuel (fat). While you may lose the same amount of weight on a carb vs low carb diet if they have the same deficit, being adapted to fats makes it easier to increase the deficit. "The wall" is much easier to pass in your workout once keto-adapted. That being said, becoming keto-adapted is very difficult. Too difficult to be worthwhile for some people; some would rather just fight through "the wall" every work out session; to each his own.
The body is already adapted to burning fat. The wall doesn't occur because your muscles can't burn fat; it occurs because fatty acids can't pass the blood-brain barrier, so the brain cells can't burn fat, and once blood glucose and liver glycogen are exhausted, the brain runs out of fuel until ketogenesis kicks in. Ketone bodies can pass the blood-brain barrier, and once they're in neurons, they can be used as fuel through a pathway that introduces them to the citric acid cycle.
In most cases, though, athletes only exhaust glycogen (hit "the wall") after 2 hours or more of moderate exercise. If you hit the wall during every workout, either your typical workout is very long or there's something else going on! It might be shorter for those on a large calorie deficit, but conversely there's some interesting evidence (from a mouse study, though) that calorie restriction results in more efficient production and use of free fatty acids. And there's evidence that athletes who train with low glycogen become more efficient at fatty acid oxidation (through β-oxidation and the citric acid cycle in muscular mitochondria, independent of ketogenesis in the liver). My own experience as a middle-of-the-pack endurance athlete (long-distance cycling, distances up to 125 miles) is that I could stave off the wall (or bonking, as cyclists say) indefinitely as long as I took in 200-250 calories an hour of easily digested carbs, and that was while on a daily deficit of 500-600 calories.3 -
Animals' bodies adapt to the fuel they experience the most, we are not an exception: https://www.ncbi.nlm.nih.gov/pubmed/23085190
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OP, the body ALWAYS burns fat. Keto people will demonize carbs, but the reality is that if one is in a calorie deficit, one will lose excess body fat. Do you know when most of your excess body fat is burned off? During rest, not exercise.
A.C.E. Certified Personal and Group Fitness Trainer
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Been in fitness for 30 years and have studied kinesiology and nutrition
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Glycogen is just a limited store of quick-access energy. It will partly run down even if you have a high carb diet, if you maintain a consistent deficit. I eat ~50% carbs, but my glycogen is not at full capacity. I know this because if I eat a large carbsy meal or have an unusually carbsy day, my weight will immediately increase due to putting down glycogen.
Think of it like the body's current account, and the fat is the savings account. If you spend more than you earn over an extended period, the savings account balance will inevitably decrease.
What happens with the current account, whether you keep it full, empty it out or somewhere in between, may make apparent differences in the short term but has very little impact in the long term.
As far as I can make out, on a high carb diet in a deficit, the body seems to go for "somewhere in between", keeping some glycogen stored but not the full amount. It does not make sense for the body to burn all the glycogen before moving on to fat, as it wants the glycogen to provide quick energy to the muscles. So it will burn fat where it can and save the glycogen (some, not all) for when it's needed.0 -
DShaull315 wrote: »Animals' bodies adapt to the fuel they experience the most, we are not an exception: https://www.ncbi.nlm.nih.gov/pubmed/2308519
That doesn't prove that we are more efficient at burning body fat when we cut carbs, which is the original claim you made. Yes, our bodies have methods of burning whatever fuel we give them, that will never be disputed.0 -
Studies have shown that after 12 months there is very little difference in fat loss between those on a low carb diet and those that aren't. Ketosis is not a magical solution to lose weight quicker but a tool to lose weight if the diet works for you.
Initial quick weight loss is mainly water.4 -
I know several people who love low carb and some who seem to only stick to their diet when they are following a keto diet. I think that's great that they found something that helped them stick to a deficit. It's not for me. I think people should try out various eating styles and see what they can stick to. That's the real secret of fat loss, eating and exercising in a way that works best for you long term.3
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DShaull315 wrote: »Animals' bodies adapt to the fuel they experience the most, we are not an exception: https://www.ncbi.nlm.nih.gov/pubmed/2308519
That doesn't prove that we are more efficient at burning body fat when we cut carbs, which is the original claim you made. Yes, our bodies have methods of burning whatever fuel we give them, that will never be disputed.
So in the study they had the high-fat diet rats, and high-carb diet rats. They compared exercise performance and didn't see a statistical difference. And then when they switched the diets (fat diet rats ate carbs, carb diet rats ate fat) the carb diet rats underperformed not just the fat diet rats, but also their previous performances when they were eating carbs. Does that not show they weren't adapted for that fuel?0 -
DShaull315 wrote: »DShaull315 wrote: »Animals' bodies adapt to the fuel they experience the most, we are not an exception: https://www.ncbi.nlm.nih.gov/pubmed/2308519
That doesn't prove that we are more efficient at burning body fat when we cut carbs, which is the original claim you made. Yes, our bodies have methods of burning whatever fuel we give them, that will never be disputed.
So in the study they had the high-fat diet rats, and high-carb diet rats. They compared exercise performance and didn't see a statistical difference. And then when they switched the diets (fat diet rats ate carbs, carb diet rats ate fat) the carb diet rats underperformed not just the fat diet rats, but also their previous performances when they were eating carbs. Does that not show they weren't adapted for that fuel?
Our bodies need time to adjust from fast energy sources to digesting mostly fat in order to withstand endurance. That's far from a shocking conclusion. I'm really not sure what you are trying to prove here because it still doesn't support your claim that our bodies struggle to burn body fat thanks to eating carbs. All it proves is that it takes time for our bodies to switch what and how it is metabolizing our food.4 -
DShaull315 wrote: »I think most people will know that when I say limitless I don't mean 100%. It's in reference to the fact that in our evolutionary history we would have needed to go without carbs for periods of time, and in our current civilizations we never have to.
Actually, historically, people's diets was heavily carbs based. (Unless you were very wealthy.) If you didn't have carbs you probably didn't have anything.
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Which has nothing to do with the efficiency of the body burning body fat even if one consumed moderate carbs in their diet.DShaull315 wrote: »DShaull315 wrote: »Animals' bodies adapt to the fuel they experience the most, we are not an exception: https://www.ncbi.nlm.nih.gov/pubmed/2308519
That doesn't prove that we are more efficient at burning body fat when we cut carbs, which is the original claim you made. Yes, our bodies have methods of burning whatever fuel we give them, that will never be disputed.
So in the study they had the high-fat diet rats, and high-carb diet rats. They compared exercise performance and didn't see a statistical difference. And then when they switched the diets (fat diet rats ate carbs, carb diet rats ate fat) the carb diet rats underperformed not just the fat diet rats, but also their previous performances when they were eating carbs. Does that not show they weren't adapted for that fuel?
Having done this for YEARS with clients, I haven't yet recommended a low carb/no carb diet to anyone with good general health. The exceptions would be diabetics. And they all lost fat weight just fine by CICO.
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
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