Carbohydrate Sensitivity

Have you ever wondered why some people don’t gain even a single pound after consuming so many bananas & rice, but you seem to gain weight by just having a potato? Maybe it is your genetic predisposition to carbohydrates. Just because you are carb tolerant, doesn’t mean that you should do away with carbs.

Before we drill down more into this, let us ask ourselves- “Does carb tolerance even exist?” Surely this is one of most discussed topics during dinner conversations, but do we really know what it means? Maybe carb intolerant people eat a lot of carbs or maybe some people cannot process the carbs as others do! The answer lies in your genes.

How genetic predisposition to carb intolerance is not the only culprit. According to a recent research, correlation between obesity & a person’s ability to make amylase, an enzyme that helps to break starch in your mouth, also has a profound impact on carb sensitivity. But why does this Enzyme differ from person to person? We human beings eat a variety of food items in our diet offering a host of macronutrients & micronutrients. So roughly we should be equal in terms of our digesting abilities. However, this is not true for all. This difference in our digesting abilities is because of genetic polymorphism.

Polymorphisms are variants in genes, DNA sequence or chromosome that show up in our physiology(phenotype). That’s what makes us different from the person sitting next to us.

Most polymorphisms are small involving a single base pair. To visualise how it plays in your body, consider changing one single letter in your book. The change is so small that you may not even notice it. However sometimes differences/changes are much bigger involving a complete chromosome. That is more like losing the entire chapter of the book. Differences like this results in huge variations between individuals 

Single point changes are called single nucleotide polymorphisms or SNP. For example, One well known SNP is a variation of the CYP1A2 gene. Depending upon which variation of CYP1A2 gene you have, you will either metabolise caffeine fast or slow. SNP gives rise to minor polymorphisms such as variations in caffeine tolerance. However polymorphisms can also result from changes in the number of genes. These are called copy number variations (CNV) that can create significant difference among people

Two main forms of CNV are duplication (adding number of genes) & deletion (removing genes). Upto 12% of DNA has CNV(s). Both differ at least 1% genetically. Even identical twins can have different CNV. 

CNV has been associated with a number of complex diseases. CNV may give a clue to carb tolerance. Salivary Amylase is an enzyme in your saliva that starts the digestion of starch. The gene that makes amylase, AMY1, varies in copy number from person to person. AMY1 genes have a huge CNV range varying from 2 to 16 copies. More AMY1 genes means more Salivary Amylase, resulting in an effective breakdown of carbohydrates. As soon as you consume rice or potato, AMY1 gets onto its work. More number of AMY1 genes means your carb digestion would be faster.

What happens in case people have a low number of AMY1 genes but live in places which are dominated by high starch/carb diets? Low copy number of AMY1 genes predisposes individuals to obesity. Besides, people with more copies of AMY1 genes have low BMI. Although, it is correct to say that carb intolerance can be a reason to gain weight but it is not the only reason.

People with more AMY1 are fortunate because: 

1. They naturally eat less: More digestion of carbohydrates in their mouth essentially means food may feel richer resulting in people feeling more satisfied & eating less.
2. They tolerate glucose better: Higher Salivary amylase means high pre-absorptive insulin response.

Based on genetic predisposition if you have low number of AMY1 genes, it does not mean that you should not consume carb, rather you should adopt the following:

1. Eat slowly & chew your food thoroughly.
2. Use probiotics.
3. Eat healthy carbs full of fibre & micro nutrients.

Do not go by what the “self proclaimed experts” tell you – consume less carb since it makes you fat. Your diet composition to a larger extent is impacted by what your genetic composition is. Are you looking to shed that extra pounds & thinking of joining a fitness center or its online version, please hang on! Do not go by their standard solution.

Let your genes decide what you should eat & how you should sweat. Sign up for our genomics based personalized fitness coaching. We use genetic insights to deliver a personalized fitness solution.

PS: Originally published on www.thesushantkumar.com