The fruit I've tested are mainly orange juice and dates, and would have ~1300 calories of each on alternating days. It's the cheapest way to get good quality fruit.Interesting comment, did you test different kinds of fruits? High fructose (apples, etc), low fructose (cantaloupes, etc)
Also how is your diet look like?
1300 calories of dates feels equivalent to ~500 calories of cheese for me, and it doesn't speed my metabolism up to meet the 800 calorie surplus, either.
I like some OJ for breakfast, and a bit spread out through the day, but eating a high-carb diet of fruit just doesnt feel good to me.