Bananas are relatively high in carbohydrate and, therefore, not the most suitable fruit for a low carb diet. It depends on your carbohydrate allowance but one banana could use up most of it. Moreover, if you were on a very low carb diet, one average banana would exceed your limit. There are far better fresh fruit and vegetable carbohydrate bargains to be had. For examples, see the page links, further down this page, listed under Related Questions.