>Honey, for instance, has a high glycemic index. Watermelon has a high glycemic index. They will not get you fat the same way cane sugar and watermelon juice will.

Aside from not being evidenced, this is irrelevant to your hypothesis. Watermelon contains little fiber even on a per-calorie basis (https://tools.myfooddata.com/nutrition-facts/167765/wt1) and honey (https://www.nutritionvalue.org/Honey_nutritional_value.html) contains almost none.