Why Shift Work Is Hard on the Body The research on shift work and metabolic health is sobering. Shift workers have significantly higher rates of obesity, type 2 diabetes, cardiovascular disease, and metabolic syndrome than day workers — even after controlling for diet quality and exercise habits. The mechanism is circadian misalignment: the body's internal clock is timed for daytime activity and night-time rest, and working against this rhythm disrupts virtually every hormonal system that governs fat metabolism. Cortisol, which should peak in the morning and drop by evening, is dysregulated …