The introduction is worth quoting

Linoleic acid (LA) (18:2n–6) is an 18-carbon n–6 PUFA with diverse effects on human physiology. LA is linked to skin barrier (1), immune (2), cardiovascular (3, 4), and neurobiological (5) functions, and, as a precursor of arachidonic acid and its metabolites, to reproductive (6), thermoregulatory, and digestive functions (7). In addition, LA is a natural ligand for PPARs (8). PPARs are intimately involved in the regulation of metabolic functions, including lipid and glucose metabolism, and they have been implicated in obesity and cardiometabolic disease risk (9). PPARα agonism may contribute to the ability of dietary LA to reduce circulating concentrations of total and LDL cholesterol (10). Finally, LA can influence biological processes via its nonenzymatic oxidation products. Oxidation of lipids in LDL is a risk marker for coronary heart disease (11). Because of its abundance in LDL and susceptibility to oxidation, LA is the most commonly oxidized species in LDL (12). The LA content of LDL reflects dietary intake (13).

Many seed oils are rich in LA, and consumption in the United States has increased substantially over the last half century (14). Much of this increase has come from soybean oil, which contains between 50% and 60% of total FAs as LA (14). Adipose tissue concentration of LA is particularly responsive to dietary LA, as demonstrated by diet modification trials (10). As such, it is used as a biomarker of dietary intake (15). We hypothesized that increases in dietary LA in the US food system have led to increased adipose tissue concentrations of LA. To test this hypothesis, we conducted a systematic literature review of studies that have reported the LA concentration of subcutaneous adipose tissue. Our findings suggest that adipose tissue LA has more than doubled in the United States over the last half century and correlates strongly with LA in the US food supply, potentially influencing numerous aspects of human physiology and pathophysiology.

Given the very long half life 680d of LA, it takes years to reduce the concentrations in adipose tissue. Dietary LA is directly associated with fatty LA deposits. The primary source of LA in the modern diet are industrial oils (seed oils, vegetable oils).

A thank you to @xep@fedia.io for the Dark Calories book recommendation, I've made it to chapter 2 and am digging through the references as they pop up.