I drank butter for breakfast for two years. Two tablespoons, blended into coffee, standing at the kitchen counter before anyone else was awake. I have a medical degree and a dental one. I did it because someone on a podcast explained the science, and it made sense to me at the time. These things always seem to make sense at first. That is the real problem. After butter came MCT oil, then coconut, then ghee, then olive. Five phases over fifteen years, each with its own expert, its own mechanism, and a fat I was told to avoid. The current villain is seed oils, and lately more executives have asked me about them than about anything else. So I read both sides properly, including the arguments I expected to disagree with. In this edition: Why the critics are right about the biology. Linoleic acid really is stored in your cell membranes and your body fat, and its share of American adipose tissue roughly doubled between 1959 and 2008. That part is not in dispute. Where the chain breaks. The one time anyone tested the DNA claim in living people, and what they actually found. The omega-6 to omega-3 ratio, and why the study everybody cites points somewhere other than where they think it does. The two randomized trials that should trouble anyone who believes this question is settled, including the one where more of the intervention group died. I do not soften it, and I explain why the margarine explanation the internet reaches for was rejected by the trial's own authors. Why the cohort studies and the randomized trials disagree with each other, and what each design can and cannot tell you. This is the part of clinical training that transfers to reading any study. Two of my own phases that turned out badly, including the one where I made things more concentrated while believing I had made them lighter. And a hallway outside a wrestling dormitory, which is where this piece actually starts, and where it ends. If you have ever thrown out a bottle of oil because of something you heard, there is a section on where cooking fat actually sits in your diet that will probably annoy you. --- Read the written edition, with all 16 references: https://www.andreheeg.com Under Load is the Sunday edition of The Upward ARC, written by Andre Heeg, MD, DDS. Evidence-led writing on executive health, longevity and performance under load, for people carrying real responsibility. Subscribe: https://www.andreheeg.com --- Studies and sources discussed in this episode are listed in full in the written edition. Key ones: Guyenet & Carlson (2015), Advances in Nutrition: the rise in adipose linoleic acid across 37 studies de Kok et al. (2003), Food and Chemical Toxicology: the human trial of linoleic acid and oxidative DNA damage Zhang et al. (2024), eLife: omega-6, omega-3 and mortality in 85,425 UK Biobank adults Hooper et al. (2018), Cochrane Database of Systematic Reviews: omega-6 fats and cardiovascular disease Ramsden et al. (2016), BMJ: recovered data from the Minnesota Coronary Experiment Ramsden et al. (2013), BMJ: recovered data from the Sydney Diet Heart Study Zhang et al. (2025), JAMA Internal Medicine: butter, plant oils and mortality Hall et al. (2019), Cell Metabolism: the inpatient ultra-processed food trial --- This episode is me reading the written newsletter, adjusted for the spoken word. Figures are rounded and citations are left out; everything is fully referenced in the written edition. I use AI to research and pressure-test the science. The thinking, the conclusions, and the writing are always mine. Nothing here is medical advice, and it is not a substitute for a conversation with your own doctor.
