It's not so much that fruit is bad for you, but rather, some fruits are high in fructose. The body can only assimilate so much fructose in a day due to saturation of absorptive enzymes. Any excess fructose that cannot be stored or used for energy will be stored as saturated fat in the palmitate form. Fructose will fill liver glycogen stores FIRST before muscle. Because fructose undergoes facilitated transport through GLUT5 transporters into the enterocytes of the small intestine under absorption, it is a s-l-o-w absorbing carb; Thus it will have a low GI. Glucose, fructose and galactose also will undergo facilitated transport through GLUT2 transporters out of the enterocytes and across the basolateral membrane.
Not all fruit is high in fructose. Also, depending on growing conditions, soils, time of year, and how ripe/unripe the fruit is, will also determine its Glycemic Index and its starch to sugar ratios. The more unripe a particular fruit is, then the more amylose and starch content will be present, therefore it will have a lower GI rating. The more ripe a fruit is, then more starch will be inverted into sugar, thus giving a higher GI rating.
One thing to keep in mind is that on a hypocaloric diet, most people will have lower levels of liver glycogen stores, therefore they would be able to consume a little fructose filled fruit. I would not really advise much fructose to be taken in on a bulking regimine due to the full hepatic glycogen stores. Fructose can be eaten you just have to know when so that you can reduce its negative fat promoting effects. Those fruits with high GI's and high glucose content, can be eaten after a workout.
MR. BMJ