Water Weight

[UrsusMinor]

I recently visited two old aquaintances who are now quite obese. Oe of the things that struck me is how swollen their feet and ankles were.

Thinking back on my own weight-loss trajectory a couple of years ago, I had the common experience of dropping weight rapidly on a low-carb diet--21 pounds in the first 28 days. "Mostly water weight," people say, dismissively.

Well, perhaps. But does anyone understand the mechanism? Yes, I know that glycogen holds 2-3 times its weight in water, but what could that account for at the outside, perhaps 7 pounds? That still leaves 14 pounds in 28 days. If it were fat, it would have to be a burnoff of 1800 calories a day (and I had a sprained ankleduring that period, so I could only walk very short distances and had to do so with a cane. It was probably the most sedentary period of my life.)

So we have to assume that some of it was water. But why was I holding so much extra water, and why, beyond the glycogen, does it fall off so fast with low carb intake? And, reflecting on my aquaintances, what is it about high carbohydrates that seems to generate edema? (These people's feet weren't "fat," but they were so swollen they were tight.) it also seems like this water loss is a good thing, and might account for the quick drop in blood pressure so many people have on low-carb diets. But what is the mechanism?Any ideas?

[Todd Becker]

Thanks for your post, UM.  I think that Gary Taubes has a good answer to your question in his recent book, Why We Get Fat.  I'll quote:

...insulin signals to our kidneys to reabsorb sodium, which in turn causes water retention and raises blood pressure.  When insulin levels drop, as they do when we restrict carbohydrates, our kidneys will excrete the sodium we've been retaining and with it water.  For most people this is beneficial, and it's the reason whey blood pressure comes down with carbohydrate restriction. (This water loss, whcih can be a half-dozen pounds or more in a two-hundred pounder, can constitute most of the early weight loss). For some individuals, though, the body will perceive the water loss as something to be prevented. It does so through a web of compensatory responses that can lead to water retention and what are called electrolyte imbalances (the kidneys excrete potassium so save sodium), and the result is [side effects like weakness, fatigue, nausea, dehydration, diarrhea, constipation [and] a condition known as postural, or orthostatic hypotension.

In this latter case, where people experience low blood pressure and other side effects, Taubes recommends supplementing the diet with sodium (to the chagrin of orthodox medicine!).  Otherwise, the reduction in blood pressure is merely an added blessing from low carb!

In short, the water loss, and more importantly the reversal of edema, is a direct cause of low carb dieting that goes well beyond the loss of water that is associated with glycogen.

[UrsusMinor]

Interesting.

The traditional standard treatment for hypertension, of course, is diuretics. Long-term use of diuretics has now been linked to the development of Type II diabetes. (So has the use of beta-blockers for hypertension.) It is interesting to reflect on what is really happening in the body when you simultaneously have high insulin levels and diuretics at work at the same time. 

A Cochrane review of using drugs to lower moderate hypertension of diabetics (140-160/90-100) into the normal range showed that there was no medical benefit. Yet it is known that untreated high blood pressure is unhealthy compared to natural low blood pressure. In other words, drugs that artficially reduce blood pressure may be the equivalent of achieving a healthy lawn by painting the grass green, and high blood pressure itself may be more of a symptom than a disease.

Perhaps low-carb weight loss tackles the core health issue...rather than painting the grass.

[shawn5]

The use of water early in the morning is more beneficial for your body,.....its true water diet is useful for weight lose,..

[dee]

Perhaps low-carb weight loss tackles the core health issue...rather than painting the grass.

Yep, there's quite a bit of talk (and a small amount of research) on how ketogenic diets combat cancer (cancer cells can't run on ketones). I assume there is a preventative effect as well (a ounce of prevention is worth a pound of cure...).

As for the glycogen weight, with the water, it would be way less than 3 lbs. It could be as little as one. Different sources quote different amounts of glycogen, and amount of water per g of glycogen. So it could be less than 1 lb (270g of glycogen at 2.7g of water per 1g glycogen). This is assuming your glycogen reserves were 100% full at the time of you first weighing, and 0% full at your last.