In this Metabolic Classroom lecture, Dr. Bikman dives into the central metabolic role of lipoprotein lipase (LPL)—a largely unsung but crucial enzyme that governs whether fat is burned or stored and even where it accumulates in the body.

LPL is anchored to capillary walls in tissues like fat, muscle, heart, and lactating mammary glands. It acts as a metabolic gatekeeper, hydrolyzing triglycerides from circulating lipoproteins (like chylomicrons and VLDL) into free fatty acids. Depending on the tissue, those fatty acids are either burned (e.g., in muscle) or stored (e.g., in fat cells). LPL activity is influenced by hormones, diet, age, exercise, and weight status, and it plays a role in both fat distribution and metabolic disease.

LPL expression is highly tissue-specific and hormonally regulated. For instance, insulin increases LPL in fat tissue (promoting fat storage) and suppresses it in muscle (reducing fat burning), whereas testosterone suppresses LPL in subcutaneous fat, especially in the buttocks and hips—explaining fat patterning differences between sexes. In contrast, estrogen increases LPL in subcutaneous areas, which supports healthier fat distribution in women. Interestingly, low-carb diets and exercise reverse this pattern, increasing muscle LPL and decreasing fat LPL, thus shifting the body into a fat-burning mode.

Ben also explains how weight loss impacts LPL expression. During weight loss, LPL activity in fat tissue tends to decline, but LPL gene expression can paradoxically increase, setting the stage for weight regain. He cites long-term studies showing that individuals with higher adipose LPL activity after dieting are more likely to regain fat. LPL in muscle tissue, however, increases after weight loss and exercise, supporting greater fatty acid oxidation. Thyroid hormone also influences LPL in both fat and muscle, revving up metabolism in hyperthyroid states and lowering LPL activity in hypothyroidism.

Finally, Ben links LPL to real-world clinical questions, including its role in insulin resistance, statin effects, thyroid hormone therapy, and sex hormone treatments like TRT. He emphasizes that LPL doesn’t just respond to metabolism—it helps define it, and that insulin is the dominant regulator of this enzyme.

Show Notes/References:

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