Jealous of Your Friends Eating Carbs, Here’s Why

Carbohydrate Resistance: It’s Real and It’s Coming for You

(Check out the trailer to the horror movie we’re trying to get made below.)

We’re not really in the movie business, but if we were, this might be a good place to start. The plot revolves around your friends feasting on bread, spaghetti, and the dessert tray, and they look and feel great; meanwhile you just start to look at those beautiful carbs and your whole world falls apart.

But here’s the twist: the villain isn’t The Carb, it’s you! It’s your genes. It’s like in the horror movies when the call is coming FROM INSIDE THE HOUSE!

So here might be the bad news: You’re not Carb Tolerant – and we will tell you why and what to do about it.

This little video we found on the webs 1. Stars a carb favorite, the banana and 2. Is a little insane, kind of what it feels like to watch your friends eat stuff you would kill for. So it makes sense. Sort of. Just watch it.

Amylase. It’s the Enzyme in your mouth in your saliva to break down carbs. And it just happens to go together with obesity. Like all things, your DNA codes for things like this and there is quite a bit of variation in how much of the stuff you get. The more you get, the better you break down carbs. The less you get, the more you hate your friends that are going wild on the bagels.

Amylase isn’t new, but linking how much of it our genes code for and how that relates to being overweight is!

The gene that makes amylase, AMY1, (isn’t that an adorable name for a gene?!) and you get somewhere between 2 and 16 copies.

You start eating a donut, AMY gets to work. You start chewing on a banana, all of your AMYs start to get busy. More AMYs means more carb and starch breakdown.

And if you’re a chimp, you only get 2 AMYs, which makes sense because our lovable long lost cousins do eat some carbs, but they aren’t sitting down to bowls of rice like the Japanese, who as a matter of fact get up to 8 whole copies. Lucky them! But if you’re snacking on reindeer up in the arctic, like the Yakut people in Siberia, you only get 4. Again, that makes plenty of sense, it’s not like they’re doing a lot of corn farming with Santa and the elves up there.


Pretty simple really. Some researchers had the same question and the answer they came up with after looking at siblings in Sweden, (342 Swedes) and other parts of the world like France, the UK and Singapore and came to the conclusion that (drum roll please….):

There can be as much as a 2 point difference in BMI based on what’s going on with your spit. That may not sound like much but in the real world:

IF YOU’RE 5’5″ that’s a 12 pound difference. 

IF YOU’RE 5’10” that’s a 14 pound difference. 

If you have more than nine copies of AMY1 then you are eight times less likely to be obese compared to someone who has fewer than four copies of AMY1.


This study of the Swedes is some pretty solid evidence to  suggest that there really is such a thing as “carb tolerance.” So at least you’re not just making it up.

If you’ve got more AMYs helping you out, you are going to eat less. More digestion in the mouth means sweeter taste and more satisfaction and less eating.

ATTENTION: This means that ANYONE eating slower and chewing more will get these benefits.

Also, due to some science that no one has figured out yet, more AMY means better glucose tolerance, so that means that foods are naturally lower on the glycemic index for them. So all of those glycemic index charts may not be quite so accurate.


Use probiotics. Studies on mice suggest that lower amylase (and associated obesity) might be related to negative changes in gut microbiota. Probiotics can’t hurt, and might help, so even if you’re not a mouse, they’re worth a try.

Eat slowly and chew your food thoroughly. It may sound simple. (And this strategy is far too often overlooked). But by eating slowly, you give whatever amylase you do have more time to break down the carbohydrates you just eat.  This puts you in the same position as someone with more amylase who eats faster.

Stop freaking out that you can’t eat any carbs. Of course you can. Just not garbage and in reasonable quantities. Mind you, if you say you’re carb resistant but you’re just piling on cheese and sour cream onto your potato and are blaming it on your genes… we have a completely separate problem.

Here is a short stack of science for you to check out it you’re feeling bored and carb curious:

Falchi M, et al. Low copy number of the salivary amylase gene predisposes to obesity. Nat Genet. 2014 May;46(5):492-7.

Mandel AL, Breslin PA. High endogenous salivary amylase activity is associated with improved glycemic homeostasis following starch ingestion in adults. J Nutr.  2012 May;142(5):853-8

Mandel AL, Peyrot des Gachons C, Plank KL, Alarcon S, Breslin PA. Individual differences in AMY1 gene copy number, salivary α-amylase levels, and the perception of oral starch. PLoS One. 2010 Oct 13;5(10):e13352

Diet and the evolution of human amylase gene copy number variation. Nat Genet. 2007 Oct;39(10):1256-60.

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