Acute stress elevates blood lipids, with the largest increases
among men and postmenopausal women. The mechanisms for the effect
are unknown, but may be due to altered lipid metabolism. This
study investigated if acute stress induces transient reductions
in triglyceride clearance in middle-aged men and women, and
determined if gender and menopause affect triglyceride metabolism.
Of the 35 women, half were premenopausal, and half were naturally
postmenopausal; men (n = 35) were age matched. Clearance
of an intravenously administered fat emulsion was assessed twice:
once during a nonstress session, and again during a stress-testing
session. During the stress session, a battery of behavioral
stressors (serial subtraction, speech, mirror tracing, and Stroop)
were performed for 40 min. The clearance rate of exogenous fat
was significantly diminished during the stress, relative to
the nonstress session. Women had more efficient clearance, relative
to men, but there were no effects of menopausal status. The
diminished ability to clear an intravenous fat emulsion during
stress suggests one mechanism for stress-induced elevations
in lipids.