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Metabolism Question

I have a metabolism related question for someone that knows more about nutrition/physiology than me. To break down my understanding of metabolism… through what i have read and understood is there are basically 2 ways the body gets energy to run.

  1. we are either burning off our glycogen stores. this is more geared towards anarobic training due to the fact that glycogen (which are sugars and very easy to break down) burns very “hot.”

  2. or we are running off of our stored fat. this is geared towards aerobic training because, being composed of a single long chain of carbons, fat is harder for the body to break down, making it burn cooler. this would be better suited for low intensity training.

so now to my question. why wouldn’t eating/drinking a meal of protein and a moderate amount of good fat PREworkout (mono or poly unsat) in a sence “turn on” the body’s mechanism for burning fat? this would help burn fat through the workout until the body swiches over to the glycogen mechanism. helping to burn excess fat. this would of course be followed be a post workout meal high in both protein and carbs to repinish glycogen. i think i have a decent understanding of nutrition but if i am wrong somebody point me in the right direction. any input (as long as it isnt ignorant) is greatly appreciated.

You are not considering how your body responds to energy demand.

You burn fat with low intensity activity or at rest, when demand is low. You don’t want to be depending on beta-oxidation when you’re trying to complete a set, it doesn’t work that efficiently or quickly. That’s why your body stores glycogen, so you have ready access to glucose that can immediately be used to make ATP.

Work out hard to deplete your glycogen, so that you force the body to replenish that glycogen when you are resting/recovering between sets and when you are not in the gym.

You can’t ‘prime the pump’ by eating fat preworkout. You CAN adapt your body to a higher fat-content diet with time, because your body can up-regulate levels of enzymes and receptors needed for lipid metabolism, to improve your body’s ability to convert stored and ingested fats to energy, sugars, and hormones. But you can’t alter the laws of thermodynamics just so you can burn more fat during each set.

thank you very much for the very informative answer… so what you are saying is that a person can adapt the body to become more efficient at metabolizing fats, but when it needs the quick energy from glycogen its gonna take it no matter when type of energy macronutrient it is used to metabolizing… that makes very good sense. so to follow up… when carbs are eaten do they all get converted to glycogen or can they be burnt up first before they get stored?

The priming idea I think came from Dan Duchane who said one should eat fruit before lifting after some period of keto dieting and prior to a 1-2 day refeed.

How carbohydrates are used depends on the amount ingested and your energy state at the time…

If you are glycogen depleted, sure, your body will try to replenish that. BUT, if you take in too much at one time, your body will do what it needs to do to reduce blood sugar levels to desirable levels, so you can store some as fat. Your body can convert some amino acids to sugars, as well as the glycerol backbones of triglycerides, so you don’t NEED sugar in your diet. Some of the pathways for converting aminos to sugar can be a bit rough on the kidneys, but you’d have to have other health issues for this to be a problem for most people.

There are plenty of other factors involved, too, so this is quite oversimplified. How your body responds to insulin levels and blood sugar levels is important, along with many other factors. Genetic predisposition plays a pretty significant role, as well, in how your metabolic engine responds to certain nutrient inputs.

[quote]Trenchant wrote:
The priming idea I think came from Dan Duchane who said one should eat fruit before lifting after some period of keto dieting and prior to a 1-2 day refeed.[/quote]

I’ve heard of guys who popped glucose tabs or sweet tarts during workouts to keep glucose levels high, I think Lyle McDonald wrote about it once or twice. I think the thinking at the time was that you could deplete all of your glycogen for the duration of a ketogenic diet, without replenishing stores, but I don’t think this is the case. I don’t think your body will ever forget how to transport and utilize glucose, though it might down-regulate transporters and enzyme synthesis in response to lack of need. That’s one reason why it’s a good idea to cycle carb intake, to prevent this down-regulation.

Good posts futurepharm