In this article, Nick Jikomes examines whether the type of fat used to fry foods influences metabolic health. He argues that French fries cooked in seed oils and those cooked in beef tallow expose consumers to very different mixtures of compounds because polyunsaturated fats are more susceptible to oxidation during cooking. When heated, seed oils can generate oxidation products such as aldehydes and other reactive compounds that are absorbed into the food, whereas saturated fats such as beef tallow are more resistant to oxidative damage.

Jikomes also reviews observational data, animal studies, and mechanistic research linking high omega-6 seed oils to obesity, fatty liver disease, and metabolic dysfunction. He highlights evidence that French fries were the strongest dietary predictor of weight gain in a large epidemiological study and discusses animal experiments showing soybean oil often produces greater weight gain, adiposity, and liver fat accumulation than saturated fats under controlled conditions. He proposes that omega-6-rich fats may increase oxidative stress and lipid peroxidation, particularly when combined with high fructose intake and low omega-3 consumption.

The author acknowledges that human clinical trials remain limited and often too short to provide definitive answers. Nevertheless, he concludes that reducing consumption of industrially processed foods rich in seed oils and fructose is likely more important than focusing on any single food item. While choosing beef tallow over seed oils may reduce exposure to oxidized fats, broader improvements in diet quality and metabolic health are likely to have a much larger impact.