St. Louis Post-Dispatch, Missouri, April 3, 1910

They’re talking about protein here with the ‘150 bananas’ number. An “average” man needs about 56 grams (46 for women) of protein a day, and a banana has about 1.1 grams, so that’s really about 50 bananas a day for a man, 42 for a woman. But that’s roughly 4450 calories for a man 3738 for a woman. 150 bananas a day would be 13,350 calories! 

That’s for the Cavendish banana though, which didn’t really become the ubiquitous banana it is today until around 1950, before then the Gros Michel was the most common type. The Gros Michel (of today anyway) has even more calories than the Cavendish, 132 vs 89, so 150 Gros Michel bananas would be 19,800 calories!