I am a serious fan of Weight Watchers as a weight loss method. Years ago I lost 35 lbs and it took childbirth and a lot of years to gain about 80% back. It is a balanced diet, as opposed to one heavily balanced in the no-fat or no-carb thing. It is much easier to do than in the "old days"!
This summer I am back in the groove and have lost 13 lbs and do not have energy problems biking. Also I usually go after lunch. However my rides are mostly in the 15-20 mile range. On a longer ride a Luna bar is good and not too high in calories.