Aside from sugar grams contained in natural foods not added to them-how many grams of pure sugar is considered too much per day?

Answer 1

The USDA and HHS jointly publish the Dietary Guidelines for Americans every 5 years. The document doesn't reference sugar directly but does make a few comments about how sugar should be incorporated in a diet.

Total discretionary calories should not exceed the allowance for any given calorie level, as shown in the USDA Food Guide (see ch. 2). The discretionary calorie allowance covers all calories from added sugars, alcohol, and the additional fat found in even moderate fat choices from the milk and meat group. For example, the 2,000-calorie pattern includes only about 267 discretionary calories. At 29 percent of calories from total fat (including 18 g of solid fat), if no alcohol is consumed, then only 8 teaspoons (32 g) of added sugars can be afforded. This is less than the amount in a typical 12-ounce calorically sweetened soft drink. If fat is decreased to 22 percent of calories, then 18 teaspoons (72 g) of added sugars is allowed. If fat is increased to 35 percent of calories, then no allowance remains for added sugars, even if alcohol is not consumed.--http://www.health.gov/DietaryGuidelines/

So, even you don't know how much fat you are consuming you can be sure that in in almost any case 2 - 12oz cans of soft drink is too much and in a lot of cases even one is one too many as most soft drinks have around 39g of sugar. Decrease your fat if you want to increase your sugar and take note of the excessive amount of sugar in a lot of our common snacks.