Carbonfiberboy 

In my experience, eating carbs before a ride isn't the best idea. And for an aerobic activity like cycling there are no bad carbs on the bike unless they're the carbs you didn't eat. The very worst thing is eating carbs about an hour before riding, because then you're starting a ride right during the low blood sugar time which follows eating carbs. For long rides, like 40 miles and up, I bring a special drink I call "food" composed of maltodextrin and a little whey protein mixed to give at least 900 calories/bottle which will last me about 3 hours of hard riding.

So what I do is eat nothing before a ride. Instead for short rides, I bring a bottle containing fast carbs and drink from it if and when I feel the need. Many times on a short ride of only an hour or so, I put the bottle back in the fridge untouched. I like stuff that comes as a powder. For the last couple of years, I've been using SIS Electrolyte Powder but there are many similar excellent products. This routine allows one to ingest the smallest number of calories necessary for the ride. Never use anything sold as an energy drink.

Eating low carb can be effective for losing weight. You can tell if it's working by weighing yourself. What often happens though is that folks become accustomed to that diet and over time, say a year or so, wind up adding more calories at which point weight loss stops.