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Body Fat & Water % : Do they change at the same rate as Weight drops

I had a couple of questions on body fat% and body water composition.
However how easy or difficult is to lose body fat% and gain body water%

1. Is there a correlation between weight loss and bodyfat % drop.
2. Is there a direct correlation between drinking "x" glasses of fluids a day and increasing body water% by "y%".
3. whats a safe rate of losing body fat% and increasing body water % on a weekly or monthly basis. what would be an achievable number ?

Thu. Mar 29, 8:06am

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These are good questions! I'd love to know the answers, too.

Thursday, March 29, 2007, 8:21 PM

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I don't know about the water percentage, but I can definitely answer you on the body fat question, from experience and research - your body fat will drop as you lose weight, but if you are not eating enough protein (many people don't realize that on low-fat diets, they're eating mostly carbs) and not doing any kind of working out, or very little, OR way too much, and not consuming enough calories for your workouts, you will actually slow down the process of losing body fat. It needs to be a nice even balance of diet and exercise in order to build muscle and lose body fat. There are a lot of skinny people who have higher body fat percentanges than heavier people.

Thursday, March 29, 2007, 8:28 PM

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LONG POST answer to question

1. There are two kinds of weight loss:

a. water loss (dehydration) - this has no effect on %body fat but will decrease the %water. If you eat salty foods, the very rapid weight gain that you notice will usually be water weight. You can lose it rapidly by decreasing your salt intake. There is also some water associated with the glycogen stores in your liver, and when you start on a diet, the body uses this source of energy before going for the fat stores, and there is a rapid drop in weight from this loss of water early in a diet that won't affect your % body fat. If you sweat a lot, you will also decrease the % of water in your body and this can become dangerous leading to low blood volume and over heating (you need to sweat to give off heat efficiently, but if your body thinks your blood volume is decreased, it tells your kidneys to concentrate the urine and your sweat glands to stop sweating so that you can push enough blood flow to your heart and brain and other tissues).

b. decreased caloric intake compared to your caloric output. This is the only way to lose body fat, but you can also lose body protein. If you increase your exercise, this tells the body to build muscle and go for the fat stores instead. But you need to have adequate protein intake, or else the body will break down protein from other parts of the body to build the muscle. If you don't exercise with dieting, you will probably lose both protein and fat. If you exercise and diet, you can tilt the scales to decreasing %body fat. You can't really control which fat in your body will be lost first. It is pretty much lost evenly throughout the body. You would hope that if you have especially fat hips or belly that more would be lost from where the most is, but alas, this is not to be...

2. Your body likes to be in water balance. If you drink more water than your body needs, your kidneys will excrete the excess water, keeping the % water at an ideal level. As I mentioned before, though, the body has a preference for conserving salt (it's thought that evolutionarily speaking, salt has sometimes been hard to obtain), so if you increase your salt intake, the body will keep it. However, since the body likes to have an ideal concentration of water in it, if there is more sodium, then the body will retain water (by peeing less...) so that the concentration of the sodium in the blood stays the same. But you will have a larger % water in your body. And you will have more volume in your blood vessels. And your blood pressure may be higher. That's why people who have hypertension are told to limit their salt intake, so they won't retain water.

a. water: Your body controls the %water, so as long as you drink enough, you shouldn't really (actually, can't really) change that percent by changing the amount you drink. It is important that you get enough water so that you prevent dehydration. Generally, if you drink enough to keep your urine light yellow or clear, you should be taking in enough. water. You should increase your water intake in situations where you are going to sweat alot. Alcohol is a diuretic and causes the kidneys to over ride the other signals it gets from the body, so if you are drinking a lot of beer or something, you may think that you are OK because your urine is clear, but you can get dehydrated in a hurry.

You may be thinking that %water is correlated with %body fat. It is true that fat tissue has less water in it than lean tissue. Here's a quote from an article I found that gives the percentages and how they change with body composition:

Date: Mon May 15 09:10:18 2000
Posted By: Jeffrey Utz, M.D., Neuroscience, pediatrics, Allegheny University
Area of science: Anatomy
ID: 956756028.An

Different people have different percentages of their bodies made up of
water. Babies have the most, being born at about 78%. By one year of age,
that amount drops to about 65%. In adult men, about 60% of their bodies
are water. However, fat tissue does not have as much water as lean tissue.
In adult women, fat makes up more of the body than men, so they have about
55% of their bodies made of water. Fat men also have less water (as a
percentage) than thin men.

So you can see three possible reasons for the discrepancies you have found:
1) Babies and kids have more water (as a percantage) than adults.
2) Women have less water than men (as a percentage).
3) Fat people have less water than thin people (as a percentage).***

b. rate of fat loss: Most experts recommend not to go under 1000 - 1200 cal per day of intake. If you take in too small amount of calories, your body thinks you are starving and will decrease your metabolism.That will be self defeating because then it will take fewer calories to maintain your weight. However, you can increase your caloric output (ie, exercise) to as high as you can, if you want to lose weight faster.

I am a PhD physiologist, not an M.D. This is not medical advice, but just general information. Hope I didn't misunderstand your questions, and sorry if I rambled too much.

Thursday, March 29, 2007, 9:42 PM

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9:42 poster

I appreciate all the info you've provided. Question on the salt thing though --- I eat a LOT of salt, and I have pretty low blood pressure. I joked with a heart doctor recently that I had to eat a lot of salt to keep my blood pressure up. He said, "that might be true." Do you know what would cause that, physiologically speaking?

Friday, March 30, 2007, 3:05 AM

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That could be very true. About 30% of people are sensitive to salt, meaning that salt intake can lead to hypertension. I think they are finding that the centers in the brain or the receptors in the kidney are especially tuned to retain the salt and therefore the water. Other people are less sensitive, and so need a normal or even high salt intake to maintain a normal fluid volume. Your kidneys probably don't reabsorb as much salt as someone with more active salt pumps. It is likely to be a normal thing for you and within normal variability for people.

Friday, March 30, 2007, 7:21 AM

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Just wanted to voice appreciation to the 09:42 poster. Cut, pasted, saved!

Friday, March 30, 2007, 8:03 AM

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Yes, thanks so much, 9:42, for your great help & useful info!

Friday, March 30, 2007, 12:29 PM

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