Why can humans only eat a certain amount of sugar per day?
You certainly can eat more than 20 grams of sugar a day. It isn’t good for you, but you can certainly do it, and many people can. A big piece of cake has more sugar in it than that. Even orange juice has more fruit sugar in it than 20 grams. But the thing is if you are diabetic, you aren’t making enough insulin, or you are resistant to insulin so that your body can’t break down the sugar in your blood after you eat it. For those who are not diabetic, restricting sugar intake is a good idea because unless you are very physically active, it gets stored as fat very fast.
