The Truth About Low-Carb Diets

Carbohydrates have definitely gotten the short end of the stick over the years. They’re the chief source of energy for all bodily functions, including nervous and muscle activity. Yet many fad-diets out there look to cut them to absurdly low levels.

The truth of the matter is that an excess of any macronutrient (proteins, fats or carbohydrates) above and beyond what your body needs on a daily basis will lead to weight gain. Let me say that again, regardless of where the calories come from, if you’re eating in excess of your daily needs, you will gain weight.

Now, you may be thinking “the last time I did XYZ low-carb diet I lost of a ton of weight really quickly.” So what I would like to do is explain how this happened and why you probably weren’t able to keep that weight from coming back when you resumed a normal diet.

When we eat, our body breaks down carbs into simple sugars that we utilize for energy. Because we’re not constantly eating, our bodies store some of these sugars in a form called glycogen which gets stored in our livers and muscles for later use. Anything in excess of that, is stored as another energy reserve, fat.

When we start a low-carb diet, we tend to see quick weight loss for two reasons:

1.      Calories In < Calories Expended

If the low-carb diet drops the total calories we’re consuming below our daily needs, our bodies must utilize stored energy (glycogen and fat) to meet caloric demands. This makes sense. When calories coming in are lower than the calories we’re burning, the energy must come from somewhere. However, this is only responsible for a small portion of the rapid weight loss many people experience when jumping on the newest fad-diet.

2.      Loss of Glycogen Means a Loss in Water

This is the biggest reason that we see such quick weight loss that we aren’t able to maintain. Under a restricted calorie diet, our bodies start to pull glucose from the glycogen stores I mentioned above. Every gram of glucose pulled from our glycogen stores also pulls almost 3 grams of water out of our muscles with it. This means that the quick weight loss we’re seeing is really from a loss of stored energy and water in our muscles, not from a loss of fat. Which also explains why the weight doesn’t stay off. As soon as we resume a normal diet and the glycogen stores are replenished, water comes back into our muscles as well.

So the real lesson here is that low-carb diets are not the weight loss godsend that many marketers have led most people to believe. While they can make a quick impact on what the scale reads, they probably aren’t going to make any dramatic changes in your weight for the long-term. Only a well-rounded diet, with a small, but manageable, caloric deficit can do that.

If you have any questions or comments, don’t hesitate to comment below or email me directly at

Nick Brennan

Founder & CEO

Unbeaten Fitness

Posted on July 1, 2014 .