M&M written content is human-created, independently researched, and filled with resources to deepen your learning. Click here to see all the ways you can support this work. Not medical advice. Summary of main points: Frying in beef tallow vs. seed oils will expose you to a very different cocktail of potentially hazardous substances. French fries cooked in seed oils strongly predict weight gain in large human data, more-so than all other other foods, yet this was downplayed in publication.