Scientists can tell how much of a certain fat (linoleic acid) you've eaten over many years by testing the fat under your skin — it acts like a living record of your diet.

Dietary intake of linoleic acid from seed oils correlates with increased accumulation of linoleic acid in human adipose tissue over time.

When people in the U.S. ate more linoleic acid (a type of fat) between 1959 and 1999, their body fat showed higher levels of that same fat—roughly 2% more for every extra kilogram of it they consumed each year.

Over the last 50 years, the amount of a specific fat called linoleic acid in people’s body fat in the U.S. more than doubled, probably because we started eating more foods like vegetable oils and processed snacks.

In the last 50 years, the amount of a certain fat called linoleic acid in people’s body fat in the U.S. has gone up a lot — more than almost any other fat we’ve seen change — and this might be affecting how our bodies work and how likely we are to get sick.

Over the last 50 years, Americans have been eating more soybean oil and other seed oils, and as a result, more of the fatty acid called linoleic acid has built up in our body fat.