Bob, it might not be quite as simple as starting to walk every day. Some folks have to turn their exercise upside-down before they "earn" extra blocks!
She should be eating at least 11 blocks, and if you encourage her to use more veggies, I guarantee you that she will have enough food!
Even at that, some people can eat a ton of veggies and feel full, yet be hungry again within 4 hours of their last meal (that would be me). So, sometimes a large volume of veggies coupled with some higher density carb, such as beans, will also do the trick.
Or, try to encourage her to drink. Fluid takes up volume, and may help her to distinguish between hunger and thirst. Believe it or not, some folks think they are hungry when they are really thirsty! Besides, it takes a lot of hydration in order to help with the fat metabolism, especially in the Zone.
Hope that is helpful!