There's clearly individual variability in daily intake of sugar. Ditto salt, and probably with some of the amino acids (e.g., leucine and isoleucine interaction with beta cell metabolism and insulin output) and fats (e.g.,diacylglycerides and striated muscle insulin resistance) as well. The dose makes the poison, we're not really sure where that borderline is - and it varies from person to person. Our activity level interacts with all this. On the other hand, it's becoming clear that we need fiber in our diets to support our intestinal flora (a symbiosis important enough that it may have originally driven the change to endothermy)
Enter foods specifically designed to encourage consumption, high in a number of these things that might be toxic (depending on consumption level) and without fiber. What could possibly go wrong?