But let's rephrase this in terms of physics. "When someone looses weight, where does it go?" Ruben Meerman has an excellent explanation of it:
In summary, you breathe it out as CO2 and H2O.
Let's back up further though, before the food you eat becomes fat. Physics says that matter is neither created nor destroyed (without releasing massively more energy than we're talking about here) so everything that goes in your mouth has to go somewhere. There are several types of things that enter your mouth:
- Water - leaves body as urine
- Fat - becomes part of the body
- Fat and Water Soluble Compounds
- Compounds we can use - becomes part of the body
- Compounds we can't use - leaves body as urine
- Some of these things spend time in the liver getting converted into something easier to use or eliminate.
- Some of these things accumulate in the liver
- Non-Soluble Compounds - leaves the body as feces
So Fat, Carbohydrates, Protein, and lots of micro-nutrients become part of the body when you ingest them. You gain weight. All macro nutrients break down into gasses when you exercise. You loose weight. Calories In/Calories Out, or to be more tangible, Mass In/Mass Out.
Fat does require more calories per gram than carbs and protein to break down into water and CO2, so you do have to work harder to convert that into a form you can expire, but let's not write it off as a diet food yet, as it may be helpful in other ways.
The real problems with the Calories In/Calories Out diet scheme are: hunger, metabolism, and feeling well enough to exercise. In other words, when you're talking about real humans, our brains and our bodies don't always comply with the plan.
I'm seriously re-evaluating the mass going into my body. My last noticeable weight decrease was two years ago, my net mass has now come back up to where it was before I started. Diet is a complex matter, especially if you have other health issues, it's not as simple as eating less and exercising more, but that does need to be factored in. It is not as simple as avoiding ingredient X or adding ingredient Y, although that does need to be considered. My primary goals right now is to home cook more of my food, continue to avoid empty calories, and eliminate snacking. This is the basic plan I was doing well on before. Hyper analyzing that and trying to replicate it with convenience foods and "healthy" snacks does not work for me.
I'd like to re-evaluate the mass leaving my body, but this is a terrible time of year to add exercise. It's getting to be dark by the time I get home. But I can make sure I'm idle less. Even just being on my feet cleaning my kitchen, or bending over combing wool will spend more calories than computer or TV time...