Leptin is a fat hormone which acts in maintaining energy balance. However, leptin levels are high in obese subjects indicating resistance to the actions of leptin. High leptin levels have been associated with increased cardiovascular and metabolic risks, but it is not clear if increased leptin or leptin resistance contributes to the increased cardiovascular risk. Further, even though leptin receptors are present in fat tissue, leptin's role in fat tissue functions are not completely investigated in humans. Based on preliminary data the investigators hypothesize that resistance to leptin action in obese adipose tissue is responsible for altering the expression of adipose tissue proteins which contribute to the development of cardiovascular and metabolic dysfunction. To test this hypothesis the investigators propose a novel study directed at investigating the leptin dependent changes in adipose tissue protein expression using adipose tissue obtained from lean and obese human subjects

Inclusion Criteria:

1. Age 18-75 years
2. BMI BMI ≤25 (lean) or >30 kg/m2 (obese)
3. Going to undergo a surgical procedure where omental and subcutaneous adipose tissue may be biopsied.

Exclusion Criteria:

Inability to provide written informed consent.

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