To the OP - if you've lost a bunch of weight and been getting back in shape by walking, my guess is that your body still needs to get used to a more aerobic ( heart intense ) workout. That will probably come quickly.
Originally Posted by
myrridin
Just about any portable food source is good as long as you can digest it while riding and it has a decent quantity of carbohydrates. Sugar in and of itself is not bad, as long as it is consumed in moderation. Fresh fruit, I like apples and bananas on the bike.
+1. Granny smith apples are one of my favorite snacks in the middle of a long ride. Bananas are good, too; it helps your legs that they have potassium in them, and they're a fairly low-cal way to get it.