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Will Carbs Make Me Fat?

With the Atkins and Paleo diets being among the most-searched health-related terms on the Internet last year, there’s no question that low-carb diets are still as popular as ever. And hundreds of thousands of corporations, trainers, and books have touted the benefits of low-carbohydrate diets for weight loss.

So, the question begs to be asked: Do carbs make us fat? 

First Thing’s First...            


Let's talk about what happens when you eat a carbohydrate…

Whenever you eat any food, your body has to break it down into smaller "chunks" in order for its nutrients to be absorbed into your bloodstream. Carbohydrates ultimately break down into different types of simple sugars called monosaccharides. Glucose, fructose, and galactose are different varieties of these simple sugars that make up carbohydrates. 

Here’s the thing: Even though carbohydrates, proteins, and fats all provide energy, glucose is our body’s preferred source of energy. In other words, carbohydrates are converted into energy quicker and easier than proteins and fats, meaning they can provide us with a little pick-me-up at a faster rate.

Our brains especially like glucose. That super-cranky feeling you get when you deprive your body of carbs? That’s your brain missing the form of energy it knows and loves best: glucose. Think of glucose like the gasoline in your car; it’s our form of “fuel.” 

Tell Me More…                                                                                         

The amount of carbohydrates you eat is one of the biggest predictors of whether or not you’ll gain weight. Certainly if you have one piece of whole wheat bread a day within an otherwise well-balanced diet, you won’t see any weight gain. But 10 pieces of bread a day? Different story. Here’s why: 

  1. As discussed, carbohydrates are broken down into simple sugars (a.k.a. monosaccharides), the major source of fuel in our bodies. 

  2. These simple sugars enter our bloodstream, raising our blood sugar levels. Cue pick-me-up.

  3. Leftover glucose is stored in our body’s cells as something called glycogen. Think of this as the reserve fuel in your car; this is the energy we call on in a state of emergency. When we get really hungry, for example, that glycogen is turned back into glucose so sugar can enter our bloodstream again and we won’t feel like we’re going to pass out.

Here’s the thing: the above steps are what happens in an ideal world where we aren’t eating carbs every minute of the day. But when you can’t put down that third helping of mac & cheese? Here’s how the process above continues: 

4. Your liver and muscles—the homes of glycogen—can only tolerate a certain amount of glycogen. If they’re full and more glucose enters your bloodstream, your liver will turn this excess sugar into fat… not ideal when you’re trying to lose weight. Remember that fat is your body’s way of storing energy for the long haul, so it’s harder to get rid of. This process would be like continuing to pump gas into your car when the tank is already full; it would overflow and serve absolutely no purpose to your car; it would just make a big mess!

The Logic Behind Low Carb Diets for Weight Loss


With limited carbohydrate intake, glucose is no longer your body’s main source of energy. So what does your body do? It says, “Hey glycogen, break down into glucose so I can get some energy!” The thing is, those glycogen stores eventually get depleted too and you need an alternative source of energy between meals. What gets called on next? Your body says, “Hey fat! Help a sister out.” 

There’s a byproduct to this process: ketone bodies, which act as alternative source of energy when glucose isn’t available. In other words, low-carb diets eventually force you to rely on fat for energy, which causes you to lose weight. (FYI: This whole process is known as ketosis.) 

A study in the International Journal of Basic and Clinical Endocrinology found that obese patients on a very low-calorie ketogenic diet—or super low-carb diet—lost twice as much weight as those on just a low calorie diet within a mere 15 days. Additionally, the weight loss on the ketogenic diet was “mainly related to the loss of fat mass,” according to the article, proving that people can have strong weight loss results on the ketogenic diet.

The trouble is, if you’ve ever experienced ketosis you’ll likely know it’s not a good feeling. Irritability, lethargy, and even impaired judgment are all associated with ketosis. Additionally, if ketone production exceeds it breakdown and excretion, ketones need to be detoxified out of the body. This can cause stress on the kidneys and overall bodily functioning. 

The Bottom Line 

Do carbs make you fat? It depends on the amount and type of carbs you’re eating. Eat too many and you’ll prevent your body from using fat stores for energy. And remember, carbs are converted to glucose. Excess glucose is eventually stored as fat. Think of it this way: carbs —> glucose —> fat. 

However, if you eat too little carbs, you’ll be tired and irritable because you’re depriving your body of its preferred source of fuel. 

The bottom line is that carbs do NOT make you fat when you eat them in moderation—and when you pick the right ones (but more on that in another post)! 

You Tell Me! 

Have you ever tried a low-carb diet? What was your experience like or what did you learn? Share in the comments below! 


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