If you're going to look at strictly molecular structure, then check this link:
http://physics.nist.gov/cgi-bin/Sta...os.pl?matno=103

According to this link, about 65% of a fat cell is carbon, 23% is oxygen and 12% hydrogen. Assuming that ALL of the hydrogen is bound to oxygen in the form of water, then a fat cell would contain about 12% water (remember it takes 2 molecules of hydrogen and 1 of oxygen to make a molecule of water).
Muscle contains more water than fat percentage-wise (still not 75%, though), but muscle is also what burns the fat so the less of that you lose, the better.
So...even assuming that all of the water is excreted when a fat cell is burned for energy, you don't get 75% of your losses coming from water, although why it would be important to you to prove that is puzzling to say the least.



I don't think there has been any argument that you need to reduce caloric intake below expenditures to lose weight. The question comes in how low they can go and not cause serious lowering of metabolic rate that may or may not be reversable when caloric intake is raised again. Keeping your caloric intake very low (well below what is needed to sustain BMR) for a prolonged period can seriously mess up your metabolism and I don't honestly think that's an effect that you want to wind up having to live with.
Something else to consider in pursuing rapid weight loss is that when fat losses are rapid, the level of Leptin in your body drops rapidly as well sending a clear signal to your body that it is starving and needs to slow the weight loss down or stop it completely. In other words, by attempting to lose weight at a rapid pace, you may very well be defeating your purpose and your body will begin to fight your efforts.

Great info Lisa...

Only one minor point of disagreement. Metabolic slowdown and dysfunction associated with energy restriction & starvation eventually snaps back to normal levels once enough calories are reintroduced to the body... at least this is what I've read anyway.

First there is an extreme state of metabolic unwellness and odd eating behavior. The depleted leptin results in insatiable binge eating behavior for some time after starvation is lifted, and this results in some weight gain to a level higher than pre-starvation levels, however in the following months binge eating behavior tapers off, food intakes adjust so as to burn off the extra fat, and eventually everyone returns to their pre-starvation weight (one caveat; if the individual was on a trajectory that promoted weight gain before starvation, i.e. a diet & lifestyle which promotes insulin resistance and hyperinsulinemia, than they will probably not lose the post-starvation weight gain and will in fact continue to gain as they had been... this probably explains the "crash dieting makes you fatter" phenomena. People who crash diet tend to be overweight, the overweight tend to have insulin resistance & hyperinsulinemia, and therefore once their diet fails they're bound to add a bunch of extra weight that their body is physically incapable of effectively burning off as a normal body would post-starvation).

You might talk to TrainerDan about that one. I remember him saying quite a while back that he had worked with several people who had seriously damaged metabolisms from prolonged calorie restriction (models, I believe) and that while it's possible to get the metabolism back to a semi-normal state once it's been that damaged, it's a long hard road to travel. I think my point, though, was that it's not necessary to restrict calories to the level that you are damaging your metabolism to lose weight and if you can't lose weight except on very low calorie levels, even with low carb, then there are already existing metabolism issues that should be addressed instead of making them worse by further restricting calories. If you can lose weight at a moderate pace of 1-2 pounds per week at, say, 1,500 calories per day is it worth risking damaging your metabolism by dropping your calorie level below 1,000 (and ignoring the hunger pangs) in hopes of quicker weight loss? For me, the answer would be a definite "no".

Hmm, maybe starvation for years and years could permanently damage metabolism, you could have a point. What I read only talked about starvation for months at a time... a relatively brief duration.

I agree with everything you are saying though. Slow losses that are considerate of your body's natural pace are the best. Intentionally speeding up weight loss too fast by semi-starvation is just setting yourself up for weight loss maintenance failure and health problems.

Lisa, the figure of 1-2 pounds per week is frequently cited as a guideline in the non-LC world. Can you comment as to whether it applies to Atkins/LC as well, or is a larger weight loss "normal", at least during the initial phases of Atkins?

That depends very much on the individual along with their age, gender, past dieting history and other factors (medications, concurrent disease processes such as hypothyroid, diabetes, PCOS, etc...). Generally, the less you have to lose to begin with, the less you will lose even during the 2 week induction period. I've seen people lose as much as 15 pounds during the first two weeks, but generally those are people who are 100+ pounds overweight when they started. I've also seen people lose only 2-3 pounds during that same 2 week period, but comparisons of how much weight was lost is fairly meaningless unless the two groups are eating indentical foods in indentical amounts and have identical metabolisms and health histories. Average weight loss seems to be about 10% of what you need to lose the first 2 weeks, then 5-10% of what you need to lose each month after that so a person starting out needing to lose 50 pounds might lose 5 pounds the first 2 weeks, then 4-8 pounds per month in the next months with ever decreasing amounts as their weight approached normal for them...or about 1-2 pounds a week.
My personal opinion is that what is considered "safe" weight loss (generally considered 1-2 pounds a week) for a body is no different whether you are following low carb or any other plan. However, on most other plans the weight loss starts out quick the first few weeks and then slows down as well.
I wouldn't consider losing 10 pounds in 2 weeks dangerous, but attempting to continue losing at that pace through starvation or any other method I would consider unhealthy and dangerous unless that person had a large amount of weight to lose and even then, the person shouldn't expect that pace to continue as their weight dropped. *shrug* this isn't a race as far as I'm concerned.