Water Weight vs. Fat Weight
Understanding the Weight You Lose on a Low Carb Diet
Quick Losses and Devastating Gains
After a week of doing a low carb diet, new dieters are filled with excitement. They’ve lost anywhere from four to ten or even twelve pounds. They conclude, “This diet works!” and their enthusiasm after that quick weight loss may motivate them to stick with the diet even when the weight loss slows down to normal levels–3 to 8 pounds a month.
But there’s a dark side to this instant weight loss. Slip up and eat a “normal” diet for a day and what happens? The lost pounds are back, all five or ten of them! The feeling of failure and distress can set the dieter on a spiral of bingeing and despair that quickly leads to their regaining of all the weight lost through weeks of dieting.
In fact, both the joy and the despair you feel in response to this rapid loss or gain is misplaced. The quick losses and gains are almost entirely water. Whether you are low carbing or not, you must burn off 3,500 more calories than you take in to lose a pound of fat and you must eat 3,500 calories more than you need to gain a pound. Despite the hype in the diet doctors’ books, low carbing does not repeal the basic laws of thermodynamics. So what is that four to ten pounds of “easy go, easy come” weight all about?
What you REALLY Lost or Gained
When you cut the carbs out of your diet, your body empties out the “emergency” stores of carbohydrate it keeps in the liver and muscles in the form of a substance called glycogen. Glycogen is a normal part of our metabolism and allows us to do energy-intensive things like sprinting, for example, by letting us draw on the carbs stored in our muscles for energy.
More importantly the glycogen stored in our liver allows us to keep our brain functioning. A person who is not low carbing needs 100 gms of glucose a day merely to supply the brain’s basic needs. If the body can’t get glucose from the diet it has two choices: use stored carbohydrate–our friend glycogen again, or convert dietary or muscle protein into carbohydrate using a lengthy process called “gluconeogenesis” which takes place in the liver. Because the body wants to avoid using it’s own muscle fibers for fuel, it does what it can to keep that liver glycogen store filled up.
Nutritional research that shows that a typical 150 lb man is carrying about three quarters of a pound of glycogen. But what most people don’t know is that each molecule of glycogen is bound to four molecules of water and water has weight too. This means that when your liver and muscles are charged up with glycogen it adds an additional four pounds or more to your body weight.
Low carbing, by cutting off the body’s supply of dietary carbohydrate leads to a rapid emptying of these liver and muscle glycogen stores. And when you lose that glycogen, you also lose the associated water. That’s during the first couple days of a low carb diet you lose weight so dramatically. It’s also why you may feel slimmer and lose “inches.” You haven’t lost fat. You’ve simply dumped the water out of your muscles.
But what happens when you go off the diet for even so little as a single meal? If you eat a significant amount of carbs, your liver and muscles grab what they can out of your bloodstream to replenish that emergency stock. As they do this, those four molecules of water join each molecule of glycogen and, as fast as you can say, “Omigawd, I cheated!” that four or more pounds you lost at the beginning of the diet pile back on.
How many carbs does it take to replenish your glycogen?
Not too many. Given the figures in Lyle McDonald’s book, The Ketogenic Diet, I figured that the three quarters of a pound of glycogen that 150 lb. man is carrying in his liver works out to only 70 gms of carbohydrate Chow down some french fries and a regular soda and you’re there. There’s an additional 120 gm in his muscles. That’s two coffee shop bagels with peanut butter.
Do you lose any REAL fat weight on a Low Carb Diet?
Probably not in the first three days–unless you cut 1200 calories out of your usual diet, too. But once you have gotten through the first week or two another benefit of low carbing kicks in that does make it much easier for most people to cut out the calories they need to cut to lose real fat.
That’s because when you cut out your carbs you eliminate the blood sugar swings that cause hunger in most people. The cravings you used to get when dieting may fade out in as little as two weeks. When you stop eating in response to those nasty hunger cravings, you will find it much easier to eat a whole lot less than you used to. It is the drop in calorie intake that follows this drop in hunger that that results in the very real and often dramatic weight loss so many long-term low carbers report.
Will you gain it all back when you go off the diet?
Many books and experienced low carb dieters warn that low carbing brings with it a “devil’s bargain.” You can lose the weight but if you do, you must make low carbing a “way of eating” for the rest of your life. The instant weight regain that low carbers experience tends to confirm that this is true, which can be very frightening if for one reason or another the dieter decides to return to a balanced-type diet.
But the good news is that this may not be as true as most people think. It is true that dieting off more that 10% of your body weight using any diet makes the body “fight for fat” when you go back to eating an non-reduced calorie diet. If you stop low carbing and start pounding the calories you will gain weight, and like any lapsed dieter, you may end up fatter than before. But the equation hasn’t changed. You still need to eat 3,500 more calories than you burn.
The only “rapid” regain the low carb dieter will experience is the water weight that comes with glycogen refilling. Once you’ve put on that four plus pounds–whatever you took off when you started the diet–weight gain will proceed slowly–probably no faster than the rate at which you took it off, and often at a slower pace if you regulate your calorie intake to match what you burn off.
This is good news, because it means that low carbing does not trap you into staying with a way of eating unless that way of eating is something you want to stick with.
But low carbers need to remember every time that every time you get on the scale your REAL weight–the weight you will be when you stop dieting– is whatever you weigh now plus whatever you lost during the first week or two of the diet.
If you go off plan for a day, don’t panic when you step on the scale. That instant three pounds is only water. Compare what you weigh–with the water–to what you weighed the last time you went off plan. It’s less, isn’t it? And that is REAL weight loss!