Adolescent Weight Management Study

Inclusion Criteria: * Body Mass Index (BMI) between 28-50 kg/m2 Exclusion Criteria: * Severe cardiovascular problems; arrhythmias * Hypertension, uncontrolled (blood pressure \>140/90 mm Hg) * Diabetes mellitus (Fasting glucose \> 126) * Other serious medical disorders that would complicate dieting such as: Ulcer disease, cancer, thrombophlebitis, liver or kidney disease * Current use of weight loss medications, amphetamines, steroids, or aspirin; medications affecting body weight * Mental retardation or genetic syndromes associated with obesity * Currently pregnant or planning a pregnancy or engaging in sexual activity without using contraceptives. All females will have a serum pregnancy test at baseline and all must agree to use contraception if they are sexually active during the study. * Glaucoma * History of major depression, bipolar disorder, or psychosis * History of anorexia or bulimia * Alcoholism and other substance abuse * Use of anti-psychotic or anti-depressant medications in the last 6 months * Highly dysfunctional family system or parental psychopathology * Weight loss in the preceding 6 months of 5% or more and/or participation in another weight loss program * Cigarette smoking or recent cessation * If taking medication for hypertension or hypercholesterolemia condition must be stable for at least 3 months prior to enrollment in the study * Chronic use of decongestants * Intolerance of SlimFast