A question on carbs

So i think we all know, gaining losing or maintaining weight is all based on energy expenditure, calories but I have a curious question. If someone need say 3000 calories to maintain their weight and they straight up eat 3000 calories of carbs in one meal, would they end up periodically gaining and losing fat throughout the day due to the fact that this would exceed the amount of glycogen that can be stored in the body, of course it depends on how much the specific person can store but lets just assume they cannot store all of it.

Answer

I’ve been kind of wondering the the same. CICO if i eat x amount of calories but mostly carbs. And expend the same or more VS x amount of calories but no carbs and expend the same or more. Maybe ELI5?

Answer

I have a hypothesis.

The liver and muscle would uptake as much glucose as glycogen that they can, the remaining would convert primarily to fatty acids and store as adipose tissue.

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/carbohydrate-metabolism

Next, given that in this thought experiment, since we are only consuming carbohydrates, we would then preferentially use carbohydrate as fuel. And since we are theoretically still in energy balance, there shouldn’t be any weight gain.

https://twitter.com/BioLayne/status/1288133116347985921?s=09

As an add-in, there is also TEF (the Thermic Effect of Food). TEF represents the portion of energy that is used to digest, absorb, and metabolize food. The TEF of carbohydrates generally falls under 5-10%. This means that, on paper, it is possible to actually lose some weight (likely a small portion) due to TEF.

https://examine.com/outcomes/thermic-effect-of-food/

Neat thought experiment!