yes you have to watch what you eat, especially as it can take a while to even get to a point of restriction and while getting to that point through having your fills, you have to watch what you eat.
Like snack, I watch everything that I eat, certain ratio of protein to carbs, a limit of 1100 cals but aim for around 1000. Having the band, I could actually eat anything I wanted and to any amount I wanted, even at almost 12 weeks post op I still do not have restriction. It takes a lot of willpower and making a change to the things that you eat. There is nothing to stop you eating high calorie foods and as such if you don't make those changes, you will think the band isn't working. It would, but its the choices of the food you eat that make it work . . .ie you!
The band isn't the answer to losing weight, its simply a tool to help you lose weight, and how it works and how well it works is very dependent upon you, your lifestyle, your food and exercise choices.