Hi DiamondCrest,
In order to lose weight one must create a caloric deficit, either through a reduction of calories, increase in burning off the calories and yes the combination of the two. Alli helps create this deficit by blocking the absorption of fat (a 60mg dose will block about 25% of the fat consumed) and the body starts to use up stored fat for energy.
At a healthy weight there normally is not enough body fat to make use of this product feasible.
It is always beneficial to change our eating habits and to include exercise, even at healthy weights. The inclusion of whole grain products, fruits and vegetables is the way to go. You may need to monitor your carbohydrate intake.
Hope this clarifies.
Sophia De Monte RPh