Just watched "That Sugar Film" on Amazon Prime. It is more like I skimmed through the film because I didn't want to be bothered with all the details and some of the flashy gimmicks the film uses to present information.
The bottom line is that an Australian man changed his diet to include 40 teaspoons of sugar per day, which according to the film is the typical consumption of the average Australian male. His total daily calorie intake was about the same as it was before he went on this diet. After 60 days he had gained a significant amount of weight and showed signs of fatty liver disease, insulin resistance, and other health problems. Then he went off of the sugar diet and within a couple of months his health and weight had returned to normal.