Elevated cortisol levels do not directly prevent fat loss in humans.

Caveats

• The claim ignores that cortisol has been directly labeled 'the antilipolytic agent' in human adipose tissue under baseline conditions (PubMed, 2000), reducing basal lipolysis and catecholamine sensitivity.
• Cortisol's lipolytic effects are conditional — they require co-factors like insulin or adrenaline — and under chronic stress (the scenario implied by 'elevated cortisol'), insulin co-elevation typically shifts cortisol's role toward fat storage, not mobilization.
• The claim does not distinguish between acute and chronic cortisol exposure, which have substantially different metabolic effects; chronic elevation is associated with visceral fat accumulation, insulin resistance, and impaired fat metabolism across multiple high-authority studies.