Earlier quoted context omitted.
Potatoes are high carb, and high carb makes most people fat. To be fair, bananas are high carb too. Also fat doesn't make you fat. A lot of people actually rapidly lose weight on a ketogenic diet with approx 70% of their food being healthy fats. The Story of Fat: Why we were Wrong about Health https://www.youtube.com/watch?v=5S6-v37nOtY
You may want to remove the "t=88s". That's an excellent video I recommended many times, by the way. It has a text version with many sources linked in the description, and the rest of the channel is very good too.
I love that channel. Entertaining, informative, and succinct. I've learned a lot from it.