I read a few days ago that excessive consumption of sugar when you already have enough food can cause metabolic syndrome.
I’ve only seen it in one place, so I’m not sure how well established it is.
Excessive consumption of sugar will cause metabolic syndrome regardless of how much you eat, but when you think of sugar, don’t just think of what you add to tea, coffee, etc or sugary soft drinks. ALL carbohydrate converts to sugar rapidly including the “healthy” whole grains. Carbohydrates need to come from low-carb vegetables and minimal fruit.
Starchy foods, if you eat them, should be no more than an occasional treat. The problem is that for too many people, it’s difficult to stop at one moderate helping because of the effect on the blood sugar