Do You Know Your Carb Tolerance? A Simple Guide to This Crucial Dietary Figure

Assessing someone's carb tolerance is one of those little diet tweaks that could have a huge difference on their performance and daily life.

Carbs don't exactly have a great reputation these days.

You've probably heard something about how carbs spike your insulin levels, and if insulin is the "fat storage hormone," then carbs must make you fat…right?

That topic is a whole article in itself, but the main thing you need to know is that carbs do not make you fat. Only overeating does.

But, that's not to say carbs are beneficial for everyone.

Some people thrive on loads of carbs and feel great when eating them, while others feel sick by just looking at a potato. How can that be?

The reason carbs affect people differently is due to something called carb tolerance. Carb tolerance is the reason there's so much conflicting research on low-carb dieting.

Certain studies found that low-carb groups came out on top when it came to fat loss, yet others found high-carb groups fared better.

A 2016 study found that women who were carb intolerant lost more weight on a low-carb diet and were also more adherent to a low-carb diet as compared to a high-carb diet. Now, this doesn't mean carb intolerant individuals can't lose weight on a high-carb diet. They certainly can, and over the long-term, it seems they lose weight as effectively on a high-carb diet as they do a low-carb diet.

What is Carb Tolerance?

Simple: it's how well your body tolerates carbs.

As I previously mentioned, people have varying responses when it comes to consuming carbs. This mostly comes down to two factors:

  • Their genetics
  • Their insulin sensitivity

I'm not going to get fancy here and spout biology jargon at you, but let's just say some people don't produce enough of a certain enzyme that's responsible for carbohydrate digestion. In fact, a 2014 study found that people with less of this enzyme are generally predisposed to obesity due to the high-carb diets typical of average Americans. However, those who have higher-than-usual amounts of the enzyme have lower BMI and may feel that carbs taste "sweeter" or "richer" than your average person.

When carb intolerant people consume carbs, they typically experience symptoms such as:

  • Bloating
  • Fatigue
  • Brain fog
  • Increased hunger

Another aspect of carb tolerance is your insulin sensitivity.

Insulin sensitivity refers to how your body responds to insulin, an important hormone. When you eat a meal, insulin is released to shuttle nutrients from your meal to different cells in your body. If your cells are resistant to insulin, then you need to produce a lot of it for it to be able to do its job. This can slow down your rate of fat loss, but it doesn't directly stop it. Studies have shown that even insulin resistant people can still lose fat on a high-carb diet, provided they're in a caloric deficit.

And that's the main point I want to hammer home: low-carb diets are not necessary for fat loss, but they can definitely help in the case of carb intolerance.

As I've mentioned, insulin resistant people were more adherent to a low-carb diet than a high-carb one, and adherence is the single most important aspect of any diet.

What to Do if You're Carb Intolerant

Although the simplest way to know if you're carb intolerant is if you experience the aforementioned symptoms after consuming carbs, a doctor can also run some tests (such as an oral glucose tolerance test and a fasting blood insulin test) to help you know for sure.

If you have reason to believe you're carb intolerant, here are some tips on how to make the most of it.

  1. Decrease your carbs. You don't necessarily have to go full no-carb, but slowly decreasing your carb intake until you find a sweet spot with few symptoms is a great idea.
  2. Get down to a low body fat. Studies have shown that higher body fats are typically associated with a lower insulin sensitivity, so if you want to optimize it, getting lean should be one of your priorities.
  3. Make sure you train with resistance frequently. Something that most of you are probably doing already, but for those who aren't, now's the time.
    Resistance training has been consistently shown to improve insulin sensitivity in people with or without diabetes.
  4. Get a good night's sleep. Sleep is so underrated for muscle growth and fat-loss purposes, and its effects on insulin sensitivity are well documented.
    For example, in one study reducing sleep to 4 hours resulted in immediate decrease in insulin sensitivity and other health markers.
  5. Reduce your stress. Along with sleep improvement, stress reduction is a very underrated method of improving your results, including insulin sensitivity.
    High levels of mental stress cause high levels of "stress hormones" to stay active in your system, which ultimately leads to insulin resistance.

Assessing someone's carb tolerance is one of those little diet tweaks that could have a huge difference on their performance and daily life. While carb intolerant people can lose weight on a high-carb diet, dietary adherence and enjoyment is typically much greater on a low-carb diet. Find what works best for you and stick to it.

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