Re: Do carbonhydrates turn to fat?

Johan,

Great last name!

This is a common source of confusion for many people who are concerned with 
fitness and diet, but I think I can help you and your friends pretty easily. 

The first thing to remember is that carbohydrates, fats, and proteins are 
completely separate things, composed of totally different building blocks 
(sugars, fatty acids, and amino acids, respectively) that are synthesized in 
your body by completely different metabolic pathways. The only way in which 
they could possibly "turn into" each other would be if your body broke the 
building blocks down into individuals atoms and fragments of molecules and 
reassembled them into one of the other building blocks, which your body 
never does. So carbohydrates, fats, and proteins never directly convert from 
one into another, although as I will tell you later the energy gained from 
burning one of them can be used to power the assembly of another from its 
building blocks.

The second thing to remember is that sugars/carbohydrates are basically 
energy sources for the short term, whereas fats are energy sources for the 
long term, or energy storage devices. As far as I understand things, the 
only connection between sugar and fat increase/decrease is that when you 
take in more calories than you use, your body stores the excess as fat; 
conversely, when you take in less calories than you use, your body burns 
fats in order to release the extra calories from them to use for the work it 
is doing. A useful analogy to think of is to imagine carbohydrates are like 
coins and fats are like paper money, and your body is like a system in which 
work is paid for with this money, and in which work tends to be paid for 
usually with coins. If you are paid more coins than you spend, your body 
converts the extra into paper money and stores it; if you need to spend more 
money than you have in coins, your body converts some paper money into coins 
and spends that in addition to whatever regular amount it has.

The third thing to remember is that proteins, specifically proteins in your 
muscle cells/fibers, are what do the mechanical work when you exercise, and 
they get damaged when you exercise. After exercise, your body rebuilds 
proteins in your muscle cells/fibers and even makes more than you had before 
by using energy (obtained by burning carbohydrates and fats, but only for 
the energy) to build proteins up from the amino acid building blocks. This 
is the only connection between sugars, fats, and proteins.

So, if it helps, you are all kind of right and kind of wrong. Sugar does not 
burn fat into protein, and it does not turn completely into fat. 
Carbohydrates and fats are the energy sources used to run the protein-based 
machines that run your body.

Chris Larson