This study will assess the safety, tolerability, pharmacokinetics (explores what the body does to the drug), and pharmacodynamics (explores what a drug does to the body) of single doses of JNJ-38431055, sitagliptin, and co-administration of JNJ-38431055 and sitagliptin in healthy overweight or obese adult male volunteers.

This is a double-blind (neither physician or volunteer knows the name of the assigned study drug), placebo controlled (substance containing no medication), study in healthy, overweight or obese adult male volunteers. For each volunteer, the study consists of a screening phase (up to 30 days), a treatment phase during which volunteers will receive 4 study treatments in a randomized (study sequence assigned by chance) sequence (28 days), and a follow-up phase (10 days). During the treatment phase there will be at least 7 days between each of the 4 treatments. The four treatments will be JNJ-38431055, sitagliptin, JNJ-38431055 and sitagliptin, and placebo. The following safety evaluations will be taken throughout the study: Electrocardiogram (an ECG is a painless procedure that gives a picture of the electrical activity of the heart), blood pressure, heart rate, and blood samples for laboratory tests. The primary outcome will be the effect of JNJ-38431055 and sitagliptin on glucagon like peptide-1 (GLP-1) levels. Study drug will be administered as single oral doses separated by at least 7 days. The four treatments will be JNJ-38431055, sitagliptin, JNJ-38431055 and sitagliptin, and placebo.

Inclusion Criteria:

• Body Mass Index (BMI) between 27.0 and 38.0 kg/m2 (inclusive)
• Healthy on the basis of physical examination including medical history, vital signs, 12-lead ECG, and all other screening lab tests
• Men must agree to use a double barrier method of birth control (e.g., condom for them and use of spermicide with diaphragm, hormonal contraceptives or intrauterine devices by female partner) during the study and for three months following the last dose of study medication, and to not donate sperm during the study and for 3 months after receiving the last dose of study medication

Exclusion Criteria:

• History of, or currently active, illness or medical condition or disorder that the Investigator considers to be clinically significant
• Smoker or tobacco user within the past 6 months
• History of recent major surgery (within 6 months of study start)
• Positive test for alcohol and/or drugs of abuse
• Psychological and/or emotional problems, which would render the informed consent invalid, or limit the ability of the volunteer to comply with the study requirements
• Any condition that, in the opinion of the investigator, would compromise the well being of the volunteer or the study or prevent the volunteer from meeting or performing study requirements