Has anyone ever recommended that you should try a low-carb diet? In as little as a couple of days, combined with moderate physical activity, one can expect to lose 5-10 lbs, people claim. But what are you REALLY losing on a low-carb diet? Let’s take a closer look at the relationship between energy stores and bodyweight to determine what causes this sudden and dramatic weight loss.
The major energy stores in the body are fat and glycogen (“carbs”). Whereas fat storage can vary dramatically from person to person, your body can only store a limited supply of glycogen within the muscle and liver.
For example, let’s look at a 130lb female with 25% body fat through the underlying principle that 1 pound of body fat provides 3,500 calories. She would have energy stores of 113,750 calories in the form of fat. In contrast, stored carbohydrate (glycogen) in the muscle and liver at absolute maximal levels amount to just 500 grams, or about 1 pound. Each gram of carbohydrate providing 4 calories, amounts to 2,000 calories of stored energy.
In the above example, fat accounts for over 55x the amount of stored energy of carbs! One critical component for the dramatic difference in energy storage capability is water association. Every gram of glycogen in the liver and muscles provides 4 calories of energy and is accompanied by 3-4 grams of water. In contrast, 1 gram of fat provides 9 calories of energy but only needs 1 gram of water. In a nutshell, fat provides more energy for less water.
So when you go on a low-carb diet, what you’re REALLY losing is WATER WEIGHT, not fat. Eating less carbs means less glycogen is stored in the body, and less water to accompany it. There is no lasting change in body composition. Your “low-carb diet” could help you lose fat, but it’s not for the reasons you think.
by Joe Ferraro