Seasonal Variation in Lipoprotein Lipase and Plasma Lipids in Physically Active, Normal Weight Humans*

Abstract

Adipose tissue lipoprotein lipase (ATLPL) provides free fatty acids (FFA) for storage in adipocytes, whereas in skeletal muscle LPL (SMLPL) provides FFA for oxidation. In hibernating animals, the level of SMLPL is relatively higher in summer than winter (promoting fat oxidation), whereas the opposite is seen with ATLPL. A patient-controlled study was designed to determine whether such seasonal variation occurs in normal weight humans. Eighteen subjects were studied in the summer and winter. After 2 days of a standardized diet, they underwent muscle and adipose biopsies for LPL activity, assessment of fitness by V̇O2 max, and determination of body composition by hydrostatic weighing. The percentages of body fat, body mass index, V̇O2 max, insulin, glucose, FFA, glycerol, and leptin were not affected by the season. Total cholesterol was higher in the winter than in the summer (157 ± 5.5 vs. 148 ± 4.2 mg/dL respectively; P = 0.03). The ATLPL activity was also higher in the winter than in the summer (4.4 ± 0....