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Can Genetics Play a Role in How Many Carbs You Can Eat?

Ever wonder why some people can eat starchy foods all day long and not gain an ounce of weight, where as others swear that just the thought of eating something slightly starchy make them gain weight? Well, now we know why…

Genetic polymorphism is the new buzzword for why some folks can eat carbs all day and not gain weight or suffer the blood sugar highs and lows that some people do.

When it comes to carbs, genetic polymorphism refers to the way the salivary amylase gene copies are associated with the risk of obesity in humans.  In other words, depending on your cultural heritage and the diet of your ancestors, you may be genetically predisposed to be tolerant or not tolerant to eating carbs.

How Genetics Plays a Role

Genetic polymorphisms are natural variations in our DNA that show up in our bodies or our behavior.  Humans have evolved to eat a wide range of macro and micronutrients.  Because people have lived in different climates and geographies we’ve had different food sources and our bodies have adapted to the foods that our ancestors ate the most of.  If your ancestors ate more carbs chances are good you have more copies of the AMY1 gene.

The AMY1 gene is strongly associated with obesity.  The AMY1 gene affects a person’s ability to make amylase which is an enzyme that aids in the digestion of starch.  People can have anywhere from 2 to 15 copies of the AMY1 gene.  Researchers estimate that for each additional copy of the gene people are at a 20% less risk of becoming obese.  How many copies of the gene each person carries vary greatly.  People with fewer AMY1 genes are also at greater risk of developing insulin resistance and diabetes.  Researchers have known for years that cultures that ate diets high in starch had more AMY1 copy numbers along with more amylase in their saliva.  Cultures with a tradition of agriculture like Japan have an average of 7 copies of AMY1 while cultures in the arctic circle with a high protein/high fat diet have an average of 4 copies of AMY1.

Breaking it Down

People with higher levels of the amylase enzyme are better able to digest carbohydrates.  The more amylase in your saliva, the more carbs you can eat without gaining weight.  This explains why some people become obese while consuming a similar amount of carbohydrates to those who stay thin.  Carbohydrates are digested and used differently from person to person.  Amylase begins to work on starches in the mouth as soon as you begin to eat.  Amylase breaks down starches into sugar, making them immediately available for energy.  When eaten in moderation and within recommended guidelines, there’s no evidence to suggest that carbohydrates are unhealthy for those who tolerate them well.  The way different people tolerate carbs depends upon many other non-genetic factors as well, including overall health, diet & exercise.

Making Carbs Work for You

If you’re one of the lucky ones that can tolerate carbs really well you may be able to get away with eating more carbs.  But that doesn’t mean you should be eating refined, processed carbs either.  No matter what your genetic carb tolerance factor may be, you should always eat as much real whole foods as possible and minimize or eliminate any refined and processed foods.

Here’s the deal… just because you look good on the outside does not mean you’re healthy on the inside.

Now, if you’re like most people I know and is not genetically inclined to be able to eat as much carbs… here are some tricks you can implement into your diet that should help:

  • Eat slowly:  Taking the time to chew your food thoroughly will allow the amylase in your body to break down the starches into sugars.
  • Choose whole grains (gluten-free preferred): Although it’s best to avoid grains, if you’re going to eat grains, it’s best to go with whole grains, preferably gluten free and avoid refined and processed carbohydrates.  Whole grains have more dietary fiber which lowers your insulin and minimizes your fat storage.  BTW, it’s important to keep in mind, recent studies have found that gluten can cause problems, even for people that have tested negative for gluten sensitivity
  • Choose low glycemic index fruits:  Fruits with a low glycemic index won’t spike your blood sugar levels as much, thereby lowering your insulin and ultimately decreasing fat storage.  It also helps reduces your risk of insulin resistance and diabetes.
  • Eat raw vegetables and fruits:  Raw veggies and fruits have more digestive enzymes than processed foods, which make digestion more efficient and it has much higher fiber content which helps slow the absorption of sugar.  Slower sugar absorption means lower insulin and hence less fat.
  • Keep your digestive flora populated: Supplementing with probiotics and eating fermented foods will help keep your digestive tract healthy.  Properly functioning digestive system is key to optimum hormonal function which helps lower excessive fat storage.
  • Eat most of your carbs after exercising.  After your workout is the best time to eat carbs since majority of the sugar from carbohydrates will be used to replenish your depleted muscle glycogen.  The best type of workouts are short bursts of high intensity exercises that really work your muscles like HIIT or circuit weight training.  The more you use up your glycogen, the better your body will utilize carbs as energy and not store it as fat.

While genetic does play a role in how much carbs your body can tolerate, there are ways to make carb consumption work for you.  That being said it’s always best to stick to a diet that’s conducive for you.  A diet that optimizes your health is the best diet for you, whether it’s low carb or not.

References
  • http://www.precisionnutrition.com/carbohydrate-tolerance-genes
  • http://robbwolf.com/2014/01/15/understanding-genetic-differences-carb-metabolism/
  • http://chriskresser.com/the-roundup-27

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