The pancreatic hormone insulin regulates the trafficking and metabolism of carbohydrate and fat. Since insulin influences fatty acid flux in fat tissue, and manipulating insulin can influence body fatness, this has raised the possibility that insulin plays a role in common obesity. Two competing hypotheses propose that 1) elevated insulin is a compensatory response to insulin resistance that develops with fat gain, or 2) elevated insulin outpaces insulin resistance and favors fat gain. Each hypothesis appears to be supported by a large amount of evidence. This presentation will outline a framework capable of reconciling this seemingly conflicting evidence.