The thing is, you eat less, your body conserves energy when not working out. And the workouts are more challenging because you don't feel like doing them. Or,

The thing is, you eat less, your body conserves energy when not working out. And the workouts are more challenging because you don't feel like doing them. Or, you work out more, but then you get a lot more hungry. So you end up eating more. If you try to fight both these conditions, then you end up miserable (i.e., constantly hungry, or miserable when trying to do more exercise). What is really needed is lifestyle tweaks. For example, if it is a habit to grab a donut or two from the box that someone brings into the office, you need to figure out how to not do that (i.e., relate that donut to doing an additional workout) -- eventually you may be able to convince yourself that the donut is poison, and therefore avoid it. For the exercise part -- first get in shape (takes about a month or two of daily 1-hour aerobic exercise such brisk walking or using an elliptical). Then, if you are close enough to work, at the start of spring start riding a bicycle to work at least once a week. Then 2 - 3 times a week. A 15-mile ride takes about an hour, and burns enough calories that you don't really have to worry about what you eat. You can also make a habit out of going for a walk at night for an hour or so -- that should burn around 500 calories. And increase your metabolism. Also, if you typically eat fast food for lunch, change to a sandwich shop, or pack a lunch.