Inclusion Criteria:  Obese or non-obese Awaiting elective surgery Negative urine pregnancy test  Exclusion Criteria:  Active, severe medical or psychiatric illness (per DSM-V) History of depressive and/or anxiety symptoms with or without presence of a DSM-V depressive and/or anxiety disorder Current or recent (within past 3 months) suicidal thoughts/plans/attempts Current or recent (within past 3 months) substance use/abuse/dependence (Note: stable nicotine use is acceptable, non-risky alcohol use is acceptable) Active or chronic medical illness (except obesity: either obese or non-obese volunteers can enroll in the study). MRI exclusion criteria including presence of non-MRI-safe medical device(s), magnetizable objects in soft tissue, severe claustrophobia, etc. Recent (past year) PET scan(s). Lifetime excessive radiation exposure that would be exclusionary via standards of the local radiation safety committee. Current medication treatment that would impact measures of interest. Current pregnancy or recent (within the past 2 months) intercourse without an acceptable contraceptive method Exclusion criteria for Anakinra treatment.