How many teaspoons of sugar in a banana?

Dr Unwin’s charts measure a banana as 120g of peeled fruit, about one medium banana. Bananas vary a great deal in size, and a large one weighs noticeably more once peeled.

Ripeness changes a banana more than most fruit. A green-tipped banana contains a large share of resistant starch, which is digested slowly. As the fruit ripens, much of that starch turns into sugars, and studies in the GI tables show riper bananas testing at higher values. The chart’s GI of 62 is an average and does not specify ripeness.

Banana appears on more of Dr Unwin’s charts than almost any other food, and the charts do not agree exactly. The fruits chart prints a glycaemic load of 16 and 5.9 teaspoons, the value used here. The common foods chart and the fruits vs vegetables chart both give 5.7 for the same 120g at the same GI, and so do Figure 1 and the text of the 2016 paper. The sugar burden chart lists banana per 100g, at 4.9, in its column of naturally occurring sugars; scaled to 120g, that is 5.9.

None of the charts explains the difference. Both figures are recorded on the sources page.

Plantains, the starchier cooking bananas, are on the African and Caribbean foods chart, boiled at two stages of ripeness: green plantain and ripe plantain.

The other fruits on the fruits chart, all weighed at the same 120g, are black grapes, apple, watermelon, nectarine, apricots and strawberries.