Gu Gels

Gu Gels are popular among long distance runners.  People say they delay the onset of the "wall".  A "wall" is a state of the body after it has run out of fuel stored in the muscles.  Most people who run a marathon hit the wall at mile 20 mark (more or less).

I have run about half a dozen long runs of distance more than 20 miles, and I have hit the wall in every single one of them near the 20 mile mark, even though I was eating bananas, and drinking sports drinks.

I decided to try the Gu Gels in the MDI marathon first time ever, and I still hit the wall at mile 20.  I was running at my training pace.

I had the first Gel at mile 8, the second at mile 12, the third at mile 16, and the last one at mile 20.

I felt pretty good about the Gels (I love Coffee flavor so I used Espresso Lover flavor) initially, but after I had the 4th Gel in the race, my tummy told me "no more" with a feeling of a stone sitting in my tummy.  I lost appetite for anything sweet for one full day. And as I said before, I still hit the wall near mile 20 mark.
So I do not know of any advantages these Gels offer over plain bananas, other than they are easier to carry.

There are other alternatives to Gu Gels which I have not tried yet.