• All treatment-emergent adverse events occurring during the 24-week treatment period [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Absolute change in body weight from baseline to Week 12 [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]

• All treatment-emergent adverse events occurring during the 24-week treatment period
• Absolute change in body weight from baseline to Week 12

• Percent change in body weight from baseline to Week 12 [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
• Percentage of subjects achieving at least 5% weight loss from baseline to Week 12 and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Absolute and percent changes in body weight from baseline to Week 2, Week 4, Week 8, Week 16, Week 20, and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Absolute changes in anthropometric measurements (hip and waist circumferences) from baseline to Week 12 and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Changes in fasting serum concentrations of lipids from baseline to Week 12 and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Changes in summary measures derived from patient reported outcome questionnaires from baseline to Week 12 and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]
• Changes in individual item responses from patient reported outcome questionnaires from baseline to Week 12 and Week 24 [ Time Frame: 24 weeks ] [ Designated as safety issue: No ]

• Percent change in body weight from baseline to Week 12
• Percentage of subjects achieving at least 5% weight loss from baseline to Week 12 and Week 24
• Absolute and percent changes in body weight from baseline to Week 2, Week 4, Week 8, Week 16, Week 20, and Week 24
• Absolute changes in anthropometric measurements (hip and waist circumferences) from baseline to Week 12 and Week 24
• Changes in fasting serum concentrations of lipids from baseline to Week 12 and Week 24
• Changes in summary measures derived from patient reported outcome questionnaires from baseline to Week 12 and Week 24
• Changes in individual item responses from patient reported outcome questionnaires from baseline to Week 12 and Week 24

This study will examine the safety, tolerability, and body weight effect of subcutaneous pramlintide alone and in various combinations with the oral antiobesity agents sibutramine or phentermine in overweight and obese subjects.

• Overweight
• Obesity

• Drug: pramlintide acetate
• Drug: sibutramine
• Drug: phentermine
• Drug: placebo

Inclusion Criteria:

• Is obese with a Body Mass Index (BMI) >=30 kg/m^2 to <=50 kg/m^2 or overweight with a BMI >=27 kg/m^2 in the presence of other risk factors (e.g., hyperlipidemia, sleep apnea, or treatment for these conditions)
• Has been obese or overweight for at least one year prior to study start
• Either is not treated with or has been on a stable treatment regimen with any of the following medications for a minimum of 2 months prior to study start: *hormone replacement therapy; *oral contraceptives; *lipid-lowering agents; *thyroid replacement therapy; *metformin

Exclusion Criteria:

• Is currently enrolled in or is planning to enroll in a formal weight-loss program
• Is unwilling or unable to participate in a lifestyle intervention program as part of the study
• Has been treated (within the 2 months prior to study start), is currently treated, or is expected to require or undergo treatment with any of the following excluded medications: *prescription or over the counter antiobesity agents (within the 6 months prior to study start); *psychotropic/neurological agents (i.e., antipsychotic, antiepileptic, antidepressant, or antianxiety agents, or mood stabilizers); *steroids that are known to result in high systemic absorption; *calcitonin; *ketoconazole; *antidiabetic medications
• Has had liposuction, abdominoplasty, or a similar procedure within 1 year before study start or is planning to have such a procedure during the study
• Has received any investigational drug within 1 month (or 5 half-lives of investigational drug, whichever is greater) before study start
• Has previously used pramlintide either by prescription or as part of a clinical study
• Has used sibutramine or phentermine (either by prescription or as part of a clinical study) within 2 years before study start
• Has donated blood within 2 months before study start, or is planning to donate blood during the study