In most mammals, including rats and humans, sweet receptors evolved in ancestral environments poor in sugars and are thus not adapted to high concentrations of sweet tastants. The supranormal stimulation of these receptors by sugar-rich diets, such as those now widely available in modern societies, would generate a supranormal reward signal in the brain, with the potential to override self-control mechanisms and thus to lead to addiction.
Sugar is in the process of killing off those who are not adapting to our new sugar rich and starch rich environment. We can choose to go along with nature and get sick, hopefully be kept alive by medicine, or eat the way nature intended us to. This video shows a good low carb diet for other reasons. Perhaps 2 cups of each is reasonable for normal person. Iodine is not optional.