Phen-Phen, Meridia, and Buproprion (or Wellbutrin) operate by decreasing the appetite. But some are connected to serious side effects (such as Phen-Phen and heart valve damage). In general, maximum weight loss ordinarily occurs within six months of using appetite suppressants. Clinical studies advise that if a inpatient does not lose at least 4 pounds over 4 weeks on a single appetite suppressant, then the single diet pill is unlikely to help the inpatient accomplish any requisite weight loss. Osteoporosis is a metabolic bone disease marked by a progressive decrease in bone density and strength, which can lead to painful fractures of the vertebrae. Insomnia is characterized by the difficulty of sleeping and maintaining a good night of sleep.