This study will evaluate the safety and tolerability profile of BFKB8488A following subcutaneous (SC) administration in overweight and obese participants (body mass index [BMI] greater than [>] 27 to less than or equal to [</=] 40 kilograms per square meter [kg/m^2]) with markers of insulin resistance. Single ascending fixed doses of BFKB8488A will be evaluated. Participants will be randomized into 7 sequential ascending fixed-dose cohorts of BFKB8488A SC or placebo and safety reviews will be performed before escalation to higher dose cohorts. Additionally, following the ascending fixed-dose SC cohorts, a separate cohort will open to evaluate the PK of BFKB8488A after intravenous (IV) administration.