pretty stupid statement, you are listening to the morons who are anti plant based diet
the glycemic load of fruit is extremely low. fruit is mostly made up of water and a little fiber. the sugar content is super low and because of the make up of the fruit it will not illicit a spike in insulin like cake or a bagel would.
so they are WRONG. you can prove it by consuming fruit and checking your blood sugar vs. cake.
we have been eating fruit for 2M years, we evolved eating fruit. those colors we see are because of that. so fruit is an important part of our diets and where we get a lot of hydration, minerals, vitamins, anti oxidants that are ONLY found in fruits.
https://aaas.confex.com/aaas/2017/webprogram/Paper18938.html
fruit is also the easiest thing in existence for humans to digest. it requires almost zero processing for your body. that is why after you eat fruit you feel energetic and good vs. eating a steak meal for example and feeling blah. fruit is one of the only things i would ever recommend you even consume before a workout aside from fasting
now if a person wants to be a smartass they can come back and say 'but fruit is GMO'. okay i am not recommending eating bananas which have a lower water base 77% and are modified (bananas you see in grocery stores did not even exist in nature 100 years ago) and also apples are very modified. many that you see in the store were developed in a lab to withstand climate and pests. hence the 2 fruits i would avoid are bananas and apples unless you have an orchard in your yard of course you can pick.
the other problem is fruit is usually picked unripened and shipped. it is called 'saving money'. the problem with this is along the way it loses nutrition. so make sure you are buying local as much as possible. if you live in Alaska where fruit doesn't grow then i guess you are fucked. that is why people who live there have major health problems