Fruit is not inherently bad, there are just some things you need to know. Fructose, a primary sugar in fruit, is not quite as user-friendly in the human body as glucose. It is easily stored as fat and can be problematic for the liver. In fact, high fructose corn syrup has basically the same effect on the liver as the ethanol alcohol found in your favorite adult beverage. In nature, however, we find fructose present with fiber which slows its absorption and eases the load on the liver, making it less problematic to consume, but still quite easy to store.
Another thing to keep in mind regarding fruit is agricultural selection. If we were to plant the first two apple trees ever planted, and one grew sweeter apples than the other, we would certainly plant the seeds from the sweeter apples as opposed to the more bitter apples. Rinse and repeat for a few thousand years and the result will be what we see today – apples that are much sweeter than any found in nature. Essentially, the result has been the agricultural production of fruits with higher fructose content and less fiber.
The various fruits in the diets of of our hunter/gatherer ancestors were also only available seasonally. The option to buy bananas year round has really only been available for the last few decades. This means that periods of time spent eating lots of fruit would be followed by periods of time eating very little fruit, and metabolic flexibility (our ability to switch between glucose and fat for energy) would likely be maintained. Eating fruit seasonally today is not a bad idea.
Fruit juice is always a bad idea, and smoothies and shakes are for people without fat loss goals.
Long story short, fruit is not necessarily bad for you when consumed in reasonable quantities, but it must be understood that consuming all of your carbohydrates in the form of fruit will probably hinder fat loss. We often see people consume too much fruit and end up frustrated. If you don’t like veggies, eat more meat.
Go forth and be awesome.