Hello Paul,
I just listened to your Noaks-Maffetone podcast — excellent! It was from Phil’s email today that I tuned in for the first time, and will now follow.
I have a long standing question about the concept of reducing insulin spikes by combing fat into the meal. Think of the classic pairing of the peanut butter and jam sandwich, or fresh fruit with cheese, or pasta with ground beef and tomato sauce.
And then I also read about how dangerous it is to eat such combinations above because the fat inhibits the proper operation of the insulin receptors on our cells, and consequently flooding our blood with insulin. The book “Mastering Diabetes” by Cyrus Khambatta, PhD, and Robby Barbaro, MPH, goes into great detail about eating fruit but excluding fat to improve insulin sensitivity significantly.
Any guidance regarding my quandary would be greatly appreciated.
Thanks @Archy … it was a real honour to interview them.
As we always say here in both HIIT Science and Athletica, context before content. There is immense individuality with respect to the response to various food combinations. In the short term, adding a little fat (or protein / fibre) to a carbohydrate food usually flattens the glucose and insulin peaks because it slows gastric emptying and delays the rate at which glucose appears in the blood. Metabolic-ward studies that pair fat or mixed nuts with white bread or fruit show 20–40 % lower glucose excursions compared with the carb alone, despite identical carbohydrate content (e.g., Holt et al., 1995; Wakhloo et al., 2023).
Over months and years, however, the overall pattern matters more than the mechanics of a single meal. The large CGM datasets that first showcased the “banana-versus-cookie” paradox (Zeevi et al., 2015) and were later replicated in the PREDICT and other cohorts (Berry et al., 2020) reveal enormous person-to-person variation—some people spike on fruit, others on baked goods—so blanket rules rarely fit everyone. Meanwhile, chronically combining calorie-dense fat with rapidly digested starch/sugar can overload muscle and liver with both fatty acids and glucose, driving the very lipid-induced insulin resistance we want to avoid. In practice, an occasional spoon of peanut butter on an apple is unlikely to sabotage insulin sensitivity if your overall diet is whole-food-rich, and tailored to your activity level—but if you’re concerned, a brief self-experiment with a CGM (fruit alone one day, fruit-plus-fat the next) will tell you how your metabolism responds.
I wore one for 2 years (during the year+ of health issues, had some pre-diabetic tendencies but also history of hypoglycemia) and still do intermittently. It’s SO individual, but was still eye opening.
E.g. corn on the cob? Blood sugar straight to the sky.
But eat some steak before the corn? Still high but not as bad.
5 grapes? To the sky.
5 grapes but have brie first / mixed? Much more level.
White rice? Sky.
Brown rice? JUST AS BAD AS WHITE! Who knew?
Rice in my eggs? Moderated.
So it showed that order and combination both mattered, and also that you can minimize glucose spikes with mixing in fat. I didn’t know about the dangers of chronically mixing fat and sugar though, and can’t think of any signs that the combo risk/impact would have shown through my CGM. Any ideas on how to use a CGM to find those indications?
If you get a spike you’ll likely get an energy dip you’ll notice even without CGM. Another trick is to go for a short (20 min) walk round the block just after you’ve eaten.
