He says he eats 16 bananas a day to support his training: Sixteen bananas supplies 6760 mg potassium, 21 g protein, 431 g carbohydrate, 6 g fat, and 1680 kcal. Here's the essential amino acid content of 16 bananas in grams and percentage of daily requirements:
Here's the vitamin content:
They provide more than 100% of the RDIs for B2, B5, B6, and vitamin C, just shy of 100% for folate, and 50% for B1. Finally, here's the mineral content: They supply more than 100% of the RDI for copper, magnesium, manganese, and potassium, more than 50% for iron (male requirements) and phosphorus, and more than 25% for zinc and selenium. Bananas also contain a significant amount of serotonin . Connell et al reported feeding subjects 12 bananas daily:
"None of the subjects developed symptoms which could not be attributed to increased bulk alone, even though four of them ate 12 bananas daily for six days in addition to their normal diet...Most of them experienced a sensation of satiety from overeating, but none of them complained of diarrhoea, urgency, colic, or borborygmi." In male rats, a water extract of banana root "stimulated the normal functioning of the testes and exhibited both androgenic and anabolic properties."  I have not found any research suggesting that the fruit has the same ability. Alcohol extracts of banana leaf apparently have efficient antibacterial activity against multi-drug resistant nosocomial infection causing pathogens.