Medifast is what is known as a low carb diet, and like with any other, when you cut the carbs out of your diet, your body empties out the "emergency" carbohydrates kept in the liver and muscles in the form of a substance called glycogen. Nutritional research shows that a typical 150 pound man carries about three quarters of a pound of glycogen, and each molecule of glycogen is bound to four molecules of water. 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. When you start a very low carb diet and cut off the body's supply of dietary carbohydrate, this 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 the reason why, 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 and liver.

Although there is no magic equation to show how much weight loss within the first week of dieting is actual fat verses water, I stand comfortable in the area of around 2 pounds of fat loss for my first week. If a 150 pound man has about 4 pounds of water weight, then I (a 185 pound female) should have had around 5-6 pounds of water weight. Regardless, I know that I didn't lose 8.4 actual pounds of fat. I would be nice, I'd reach goal in only a couple months, but not in the slightest bit healthy - and after all, isn't that the main reason for wanting to diet in the first place? To become healthy and happy? That's my reason anyway!