[thirdcoastle]

Is alcohol a fat?  If so, how is it chemically similar?  Or is it a "carbohydrate"?
(This will solve a debate between two non-chemists).

[Dan]

Alcohols are not fats, but I suppose may be classed as carbohydrates in some cases, but generally they are not classed as carbohydrates either. I beleive that cabohydrates must have a H:O ratio of 2:1.

Fats (triglycerides) are formed from fatty acids and glycerol. Glycerol is an alcohol - a triol, and is often classed as a carbohydrate although, strictly speaking is isn't.

It has just occured to me that you may be referring specifically to ethanol C₂H₅OH, the alcohol in alcoholic drinks. This is neither a fat nor a carbohydrate.
Ethanol does have a very high calorific content though - which is the origin of the beer belly.

[sdekivit]

carbo-hydrates : C_n(H₂O)_n 

--> thus ethanol isn't a carbohydrate: C2H5OH is not equal to C2(H₂O)2

(recall for example: glucose, C6H12O6 or for example C11H22O11)

fats are esters of glycerol with fatty acids.

[Donaldson Tan]

I am quite tempted to reply that alcohol is "thin" because it is not "fat". LOL.