Lower eyelid bags that occur in younger individuals such as yourself is almost always genetic though infrequently fat protrusion as a result of weakening of the orbital septum (the structure that holds the fat back around the eye) can also occur. The fat around the eye has nothing to do with weight gain or weight loss.
The fact that Restylane helped you temporarily suggests that a permanent correction is possible. Tightening the skin with lasers, peels, or other forms of energy doesn't help the eyelid bags. Your options include either "masking" the bags by injecting a thin material such as Restylane around the puffiness and doing this on a semi-annual basis or smoothing the eyelid to cheek transition by removing or transposing the fat. In my practice, younger patients undergo a transconjunctival lower eyelid blepharoplasty with fat transposition. This entails making an incision behind the eyelid (no external scar) followed by mobilizing the fat and then 'moving' or transposing it to the hollow area below the puffiness allowing a smooth lid to cheek transition.
Patients are very happy with this 45 minute to 1 hour procedure that can be done under local anesthesia though I feel most individuals do best during the procedure with a mild amount of sedation to keep them comfortable.