• Why this topic is back
  • The new Dietary Guidelines for Americans keep a 10% cap on saturated fat.
  • The same guidelines push more protein, fewer grains and sugars, and a low-carb option for metabolic disease.
  • They also list butter and tallow as cooking fats, which can look inconsistent with the cap.
• My bottom line upfront
  • Saturated fat from minimally processed whole foods, in a lower-sugar / lower-refined-carb diet, is a different exposure than saturated fat in a standard American diet.
  • The food source and the surrounding diet matter more than a single saturated-fat number.
• Evidence bucket 1: long-term diet surveys
  • These studies use self-reported diets and track heart disease over time.
  • Results are weak and inconsistent: some link higher saturated fat to higher risk, others do not.
  • Effect sizes are small (hazard ratios ~1.1–1.4), compared with smoking and cancer (~15–20).
  • Big problems: confounding (smoking, exercise, income, access to care), “healthy user” behavior, and recall/FFQ error.
  • They also mix food sources (steak and cheese get lumped with pizza, pastries, and ice cream).
  • Useful for hypothesis generation; not strong for cause-and-effect.
• Evidence bucket 2: controlled feeding and mechanisms
  • These studies often show saturated fat can raise LDL cholesterol in many people.
  • A key mechanism: saturated fat can lower liver LDL-receptor activity.
  • Limits: LDL is a risk marker, not a heart-attack outcome.
  • Many studies miss the broader risk picture: insulin resistance, triglycerides, HDL, inflammation.
  • Practical move: measure your own labs on the diet you actually eat, including ApoB if available.
• Evidence bucket 3: randomized trials that lower saturated fat
  • People are assigned to reduce saturated fat or not, often swapping it for carbs or polyunsaturated fats (PUFAs).
  • Typical pattern: modest LDL lowering, little or no change in all-cause mortality, mixed/neutral heart attack and stroke results.
  • A major limit is duration: often ~5 years, which can be short for coronary disease outcomes.
  • Substitution matters: saturated fat → carbs is neutral or worse for heart attack risk in some trial sets.
  • Saturated fat → PUFA has a small benefit signal, but the supporting trial set has high bias risk.
• Evidence bucket 4: studies that separate saturated fat by food source
  • When saturated fat is split by source, whole-food sources (dairy, unprocessed meats, chocolate) are often neutral, sometimes favorable.
  • Many dairy findings show a small signal toward fewer cardiovascular events.
  • Processed foods that combine saturated fat + refined carbs show harm more often.
• Evidence bucket 5: low-carb and ketogenic trials
  • These are interventions where carbs drop and saturated-fat intake often rises.
  • The saturated fat shifts from processed fat+carb foods toward whole-food fat sources.
  • Typical results: lower triglycerides, higher HDL, better insulin sensitivity.
  • Often: no rise, or even reductions, in ApoB and LDL particle counts; broader risk markers improve.
  • A small subset shows large LDL rises; long-term outcome meaning is unclear.
  • Keto-CTA comments: an early plaque-progression result tied to one analysis did not match three other analyses, which showed slower progression or regression; more results are expected.
• Comment responses and takeaways
  • Allowing saturated-fat foods is not permission for a standard American diet; it fits a whole-food pattern where LDL does not automatically rise.
  • “Plant-only reversal” talking point: Ornish-style reversal programs bundle diet with smoking cessation, exercise, stress management, social support, and medical therapy, so diet alone is not isolated.
  • “Blue zones low saturated fat” pushback: Mediterranean island patterns include goat milk, lamb, pork, and cheese, not a saturated-fat–free diet.
  • Individual testing is endorsed: labs plus carotid imaging, coronary calcium scoring, or coronary CT angiography can guide personal nutrition choices.
• Close
  • Stop treating saturated fat as one thing.
  • Track food source, processing, carb context, metabolic health, and measured biomarkers.

References

• [00:05] Dietary Guidelines for Americans, 2025–2030 — https://cdn.realfood.gov/DGA.pdf
• [10:18] Longitudinal Data From the KETO-CTA Study: Plaque Predicts Plaque, ApoB Does Not — https://doi.org/10.1016/j.jacadv.2025.101686
• [10:18] New KETO-CTA Data - Clarification and Update on Cleerly — https://www.youtube.com/watch?v=aJobOSRdIOM
• [13:19] Intensive Lifestyle Changes for Reversal of Coronary Heart Disease — https://doi.org/10.1001/jama.280.23.2001