It's proven that they are through many studies. One of the aspects is insulin spikes, mentioned in another comment here. Another aspect is very well explained i

It's proven that they are through many studies. One of the aspects is insulin spikes, mentioned in another comment here. Another aspect is very well explained in this video https://www.youtube.com/watch?v=f_4Q9Iv7_Ao https://www.youtube.com/watch?v=f_4Q9Iv7_Ao (with t̶e̶x̶t̶ ̶v̶e̶r̶s̶i̶o̶n̶ and all sources linked in the description). edit: I also recommend the rest of the channel (I'm not affiliated in any way, it just explains a lot of things I've learned in the past decade in a very neat way) edit 2: Sorry, this video doesn't have text version, but "story of fat" does.