Edit: don't want to rag on you too much, but modern healthy eating trends are saturated with all kinds of insanity.
What does fresh mean in this context? I can buy them whole from the supermarket…
You could even ask why 300 calories of tar should be worse for you than 300 calories of apples.
The reason is the many other effects stuff has, besides their nutritional stats.
Wikipedia: "The European Food Safety Authority stated that fructose is preferable over sucrose and glucose in sugar-sweetened foods and beverages because of its lower effect on postprandial blood sugar levels". https://en.wikipedia.org/wiki/Fructose
"Fructose is often recommended for diabetics because it does not trigger the production of insulin by pancreatic β cells, probably because β cells have low levels of GLUT5, although the net effect for both diabetics and non-diabetics is debated. Fructose has a low glycemic index of 19 ± 2, compared with 100 for glucose and 68 ± 5 for sucrose. Fructose is also 73% sweeter than sucrose at room temperature, so diabetics can use less of it. Studies show that fructose consumed before a meal may even lessen the glycemic response of the meal. Fructose-sweetened food and beverage products cause less of a rise in blood glucose levels than do those manufactured with sucrose or glucose."
* Retinal damage to the eye
* Arterial blockage
* Oxidative stress
* Increased inflammation
* Endothelial dysfunction
* Reduced coronary blood flow
* Increased cancer risk
Let me just point to http://www.lifeextension.com/magazine/2011/1/glucose-the-sil... or https://www.atkins.com/how-it-works/library/articles/10-ways...This is all very well known and ignored by the US sugar industry which rather blames other factors. If you feed americans large amounts of glucose (they do), they will get obese and die early. You cannot argue with the numbers, because it's mostly only affecting americans who do consume sugar levels above the health risk. Blaming fructose and the liver alone is dangerous. It's the end product, glucose, and the fat reserves, not the carb. metabolism.
Second, because 300 calories of watermelon will come with all kinds of vitamins (including C and A), and lots of water.
So, it's great as there's no evidence that butter is bad.
So yeah, a bit hard to assess combined with higher life expectancy. Not impossible though, I'm sure there's good research out there.