I hate to break it to you, but in my experience, cycling has had little effect on my weight over time. Not saying I haven't become more fit, or even lost some weight riding, but usually the weight comes back eventually, usually during the winter months when the total cycling mileage falls. It really is most about your genetics, and how much you eat. So if you do stop off at a pub, maybe skip the Beer and stick to water or diet soda.