Inclusion Criteria:

• 19 - 50 years of age
• BMI 25 - 35 kg/m2
• Non-diabetic; no previous history of diabetes
• Fasting glucose <126 mg/dL at recruitment
• Male or female
• Any race or ethnicity

Exclusion Criteria:

• Any major disease including:
• Active cancer or cancer requiring treatment < 2 years (except nonmelanoma skin cancer).
• Active or chronic infections including self-reported HIV and active tuberculosis.
• Active cardiovascular disease or event with hospitalization; or therapeutic procedures for treatment of heart disease <6 months; or New York Heart Association Functional Class >2 for congestive heart failure, stroke or transient ischemic attack < 6 months.
• Uncontrolled hypertension: ≥SBP 160 mm Hg or DBP ≥95 mm Hg on treatment.
• GI disease: self-reported chronic hepatitis or cirrhosis; alcoholic hepatitis or alcoholic pancreatitis < 12 months; inflammatory bowel disease treatment < 12 months; recent or significant abdominal surgery.
• Renal disease: serum creatinine ≥1.4 mg/dL (124 μmol/L) for men; ≥1.3 mg/dL (115 μmol/L) for women.
• Lung disease: chronic obstructive airway disease with use of oxygen.
• Diagnosed diabetes (type 1 or 2), fasting hyperglycemia (blood glucose ≥ 126 mg/dL), or use of any anti-diabetic medications.
• Uncompensated or uncontrolled psychiatric disease that would impede conduct of the trial or completion of procedures.
• Phenylketonuria.
• Temporomandibular joint disorders.
• < 16 natural, fully crowned, or restored teeth in a good state of repair.
• Inadequate oral hygiene.
• Sensitivity to flavors, sweeteners, or other ingredients in sugar-free chewing gum.
• Refusal to chew gum per study guidelines.
• Currently chewing ≥5 sticks of gum per week.
• Weight loss or gain of >10% in the past 6 months except post-partum weight loss.
• Current participation in any weight-reduction program.
• Current smoker or quit < 6 months.
• History of prior surgical procedure for weight control or liposuction.
• Unable or unwilling to give informed consent; unable to communicate with clinic staff; another household member is a participant or staff member in the trial; unwilling to accept randomization; current or anticipated participation in another intervention research project that would interfere with the intervention offered in the trial; likely to move away before trial completed; unable to walk 0.25 mile in 10 minutes.
• Currently pregnant or < 3 months post partum; currently nursing or within 6 weeks of having completed nursing; pregnancy anticipated during study; unwilling to report possible or confirmed pregnancies promptly during the trial; unwilling to take adequate contraceptive measures if potentially fertile.
• Brief Symptom Inventory score (Derogatis & Melisaratos, 1983) > 90th percentile.
• Any active use of illegal or illicit drugs or history of such use < 12 months. Excessive alcohol intake, acute or chronic: average consumption of 3+ alcohol containing beverages daily; consumption of 7+ alcoholic beverages within a 24-hr period <12 months; or other evidence available to clinic staff. Subject may still be considered eligible if, upon explanation, the clinic staff believe that the volunteer can and will limit future intake.
• This is a partial listing; complete list available from PIs.