HELP! Is my metabolism messed up?

I eat 80% fat, 15% protein and 5% carbs. If protein/muscle was preferred source of fuel for my body, I would have lost lot of muscle. Yet sitting on a couch I burn 200 g of fat every day, not muscle even on days with calorie deficit. Don't believe what you read on the internet blogs. Its very consistent with the university I work with, and not something where you see body burning all the muscle.

I eat 80% fat, 15% protein and 5% carbs. If protein/muscle was preferred source of fuel for my body, I would have lost lot of muscle. Yet sitting on a couch I burn 200 g of fat every day, not muscle even on days with calorie deficit. Don't believe what you read on the internet blogs. Its very consistent with the university I work with, and not something where you see body burning all the muscle.

I don't think you're understanding the underlying processes correctly. Why do you think you would have lost a lot of muscle based on your dietary intake of 80% fat, 15% protein and 5% carbs? If you were eating at maintenance or surplus, there would be no reason for your body to break down muscle. If you were eating at a caloric deficit, it may happen (but can be preserved or minimized with adequate protein intake and heavy resistance training).

Nope, the body doesn't work that way when it comes to fuel. I will dumb down the science for you if you don't have a bio chemistry or medical background. The body breaks down ATP from either glycogen/Fat or protein/lactic acid. The liver (glycogen supplies 2 ATP, fat supplies 34 ATP and the lactic acid comes last last usually at higher intensities. The problem most people face is they do high intensity exercises where the lactic acid is primary fuel because there aren't eating enough and fat can't keep up with the energy requirement. If your body is fat adapted, it can supply the energy just fine till you increase the intensity. IYes people lose muscle but thats because they eat too little and don't work out at the right levels. Human body can adapt just fine and for thousands of years did just fine when people would go with out food for a period of time. I am done here but unless you have a medical degree or know bio chemistry stop spreading rumors or fake science.

There was a scientific experiment done on a Man who starved for weeks and how the body reacted, its widely quoted study on how the liver reacts and what fuel the body uses.

Thank you. Though I think 20lbs in 3 months is realistic considering the fact that I'm quite active.

I eat 80% fat, 15% protein and 5% carbs. If protein/muscle was preferred source of fuel for my body, I would have lost lot of muscle. Yet sitting on a couch I burn 200 g of fat every day, not muscle even on days with calorie deficit. Don't believe what you read on the internet blogs. Its very consistent with the university I work with, and not something where you see body burning all the muscle.

I don't think you're understanding the underlying processes correctly. Why do you think you would have lost a lot of muscle based on your dietary intake of 80% fat, 15% protein and 5% carbs? If you were eating at maintenance or surplus, there would be no reason for your body to break down muscle. If you were eating at a caloric deficit, it may happen (but can be preserved or minimized with adequate protein intake and heavy resistance training).

Nope, the body doesn't work that way when it comes to fuel. I will dumb down the science for you if you don't have a bio chemistry or medical background. The body breaks down ATP from either glycogen/Fat or protein/lactic acid. The liver (glycogen supplies 2 ATP, fat supplies 34 ATP and the lactic acid comes last last usually at higher intensities. The problem most people face is they do high intensity exercises where the lactic acid is primary fuel because there aren't eating enough and fat can't keep up with the energy requirement. If your body is fat adapted, it can supply the energy just fine till you increase the intensity. IYes people lose muscle but thats because they eat too little and don't work out at the right levels. Human body can adapt just fine and for thousands of years did just fine when people would go with out food for a period of time. I am done here but unless you have a medical degree or know bio chemistry stop spreading rumors or fake science.

There was a scientific experiment done on a Man who starved for weeks and how the body reacted, its widely quoted study on how the liver reacts and what fuel the body uses.

Actually, I do have a degree -- in biology from UC Berkeley, so I understand the science fairly well. But, thanks.

Once again, not sure where your conflict is here. So, far I agree with what you're saying for the most part, but your understanding of the role of lactic acid, protein and fat in cellular respiration is incorrect.

Lactic acid is a byproduct of anaerobic cellular respiration -- when there is not enough oxygen present for the higher yield aerobic respiration seen in the Krebs cycle. It only consists of the first step of glycolysis where glucose is broken down into pyruvic acid along with two ATP and the pyruvic acid yields lactic acid after a reaction with NADH. This is why lactic acid builds up in muscles during high intensity exercise -- because the body cannot provide the cells enough oxygen for continued energy release of the Krebs cycle of aerobic respiration (which provides far more ATP -- 34 or so) -- and why you will eventually cramp and will not be able to continue high intensity exercise for long periods. The better your cardiovascular capacity, the more efficient you will be in delivering oxygen to the cells and can exercise for longer at high intensity levels.

Glucose is the start of both of those processes, not fat nor protein (and certainly not lactic acid which is an end byproduct!). However, where that glucose comes from can be a variety of sources -- already present in the blood stream from carbs, glycogen stores primarily in liver and skeletal muscle, protein (from muscle) and fat (from both muscle and adipose tissue). The body will access blood glucose first, then glycogen stores. Once those are depleted, the body needs to look to both muscle and body fat for extra energy (primarily the liver converts both into glucose through the process of gluconeogenesis, which is the synthesis of glucose from non-carbohydrate sources -- i.e. protein and fat). And depending on the circumstances, the body will look to one or the other -- but often a combination of both. The key to better fat loss is minimizing the muscle used as fuel for glucose part of the equation.

So, when you attempt to talk down to someone about something, make sure you get your facts straight.

This is also why higher volume lower intensity exercise will burn a higher percentage of fat vs. muscle. It will not burn as many total calories as high intensity exercise for the same duration, but a higher percentage of the calories it does burn will be fat versus muscle because the body is able to keep up with the oxygen demands in lower intensity exercise (walk, hiking rather than sprints) and break down more fat for energy rather than muscle (after your glycogen stores have been depleted).

So, once again, I agree with you on most of your comments and don't see how any of this contradicts in any way the fact that 1 lb of fat releases 3500 kcals whereas 1 lb of muscle releases much fewer kcals (some say 600, some say closer to 1500). Or the fact that when you're in a caloric deficit, you generally lose both fat and muscle. And one of the ways to minimize or eliminate (though true elimination is difficult) is by significant resistance training and sufficient protein intake.

Once again, where is your conflict?