The Truth About “Fast Carbs” Vs. “Slow Carbs”

Posted May 29, 2013 in Diet, Nutrition Tip 3 Comments »

What are the best carbs to help you build muscle or lose fat?
Lean man and woman
More than often, you’ll get this response: “Stay away from simple carbs and focus on complex carbohydrates, since they digest slowly and provide your body with a constant stream of energy”.

I can’t tell you how many “fitness-experts” give this response to their clients on a regular basis. Of course it seems to make sense, but there is actually some science suggesting otherwise.

Many people believe that as long as a carbohydrate digests slowly, it should keep your blood sugar stable and make it less likely for you to gain fat.

But the truth of the matter is that structuring your nutrition program around “slow-digesting carbohydrates” is actually not an effective way to get the nutrition you need.

There are actually 4 primary reasons why this is the case. Let’s go ahead and take a closer look…

Reason #1 – The Glycemic Index is incredibly flawed.

In case you didn’t know, the glycemic index is a tool that judges how fast a carbohydrate digests, on the scale of 1-100. The lower on the scale, the slower it digests. The higher on the scale, the faster it digests. There’s just one main problem.

The glycemic index is based upon consuming carbohydrates by themselves and while fasting.

I’d be willing to bet that you rarely consume carbohydrates by yourself and you probably never consume them in a fasted state, except maybe in the morning when you first wake up. A well-balanced meal always contains calories from fat and protein as well and if you’re into fitness, I’m sure you already know this. By simply consuming a carbohydrate with fat and protein, the GI of that carb can be drastically manipulated.
Reason #2 – The Glycemic Index Rank Does NOT Indicate Its Effects on Insulin

Believe it or not, some “fast” carbs can actually induce a greater insulin release than certain “slow” carbs. If you don’t believe me, simply compare the insulin index alongside the glycemic index and you’ll see exactly what I’m talking about. A great example is brown pasta, which has a glycemic rating of 70, but its insulin score is only 40. An orange, on the other hand, has a glycemic rating of about 39, but an insulin score of about 60.

Reason #3 – Carbs Aren’t the Only Macronutrient that Stimulate the Release of Insulin.

Many people don’t realize that certain protein sources can have just as much of an impact on insulin as many carbohydrate sources as well.

For example, fish is about 59 on the insulin scale, which is about the same as brown rice and 20 points more than brown pasta. On the other hand, beef is about 51 on the insulin scale, which is equal to rye bread and about half of that of a white potato.

When you take protein into account, you finally realize that the glycemic index is incredibly flawed – even if you consume carbs under the glycemic index conditions.
Reason #4 – Even if you consume carbs in a fasted state by themselves it’s not going to have a lasting impact.

Unless you suffer from diabetes or some other type of blood sugar disease, your metabolism is very efficient at keeping your insulin levels under control.

If you consume 300 grams of sugar in the morning with breakfast, you’ll probably run into some problems down the road. But let’s be honest with ourselves here: I’d be willing to bet that you would never do that if you’re serious about building muscle and losing fat and even if you did, your body would still be efficient at bringing your blood sugar under control.

In Conclusion?

The whole notion of “fast” carbs vs. “slow” carbs has no true practical evidence and anybody who tells you otherwise obviously hasn’t done their homework.

It all comes down to a couple of basic principles:

1) Get a majority of your carbohydrates from high fiber, unprocessed sources. Sure grains such as oatmeal and brown rice are important, but I tend to get a majority of my vegetables from things like broccoli, spinach and asparagus.

2) Eat your carbs with fat and protein as well.

As long as you’re following these two basic principles, there’s really no need to follow the whole “fast” carb “slow” carb nonsense.

About the Author

This article was written by Drew Stegman. For more fitness information be sure to check out his site:

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3 Responses to “The Truth About “Fast Carbs” Vs. “Slow Carbs””

  1. Great Article Drew, The debate over the place of Carbs in our diet is something that I feel comes down to the each individual needs. Personally I believe moderations, control and knowing your body is a fundamental to any health diet. If you are diabetic watch those carbs, if you are a Ultramarathon runner get those Carbs. Just my two cent

  2. This can be considered a fitness myth. Thanks for explaining it properly and hopefully the beliefs of the people regarding the glycemic index will be corrected. This is actually the first time that I understand the whole concept.

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