Recent research has shown that populations who have historically had high-starch diets have developed more copies of the gene known as “Amylase” which helps to break down starchy foods.
What does that mean to you? It means that if you have more copies of this gene you are going to a) absorb more calories from starchy foods b) feel hungry more quickly and so want to eat more and c) have a higher spike in blood glucose levels making you want to eat more because our bodies “enjoy” high levels of glucose because we feel we have more energy. So, it would make sense that people with higher copies of the gene responsible for Amylase would be more likely to be obese if they eat a diet high in “starchy” foods.
But wait, not all starchy foods are created equal!
Sweet potatoes, lentils, barley, rye bread, whole wheat pasta among others are Low Glycemic Index. (Range: 0-100) This means that they are broken down more slowly than other “starchy” foods and so keep you fuller longer and don’t cause a spike in your blood sugar so that you don’t feel hungry as quickly as you do when you eat High Glycemic Index foods.
So, these foods are ‘safer’ than foods that have a high glycemic index (white rice, white bread, potato chips etc.) Also, many High GI foods are also high in fat (french fries, potato chips…) meaning that overall, they contain more calories per gram of food and so you consume more calories on average when you eat these foods.
If you have higher copies of the Amylase gene you will digest even Low GI foods more quickly than someone with fewer copies (I know… lucky dogs!) but these foods will still keep you fuller longer and keep your blood sugar more stable than High GI foods.
So… Are “Starchy” foods making YOU Fat?
Maybe – if your ancestors at a lot of starchy foods and you inherited a more copies of the Amylase gene and have a diet high in High Glycemic Index foods (and high in fat) they could, indeed, be making you Fat!