Dear Mark: Coffee and Insulin, Fat and Post-Workout Meals

In today’s edition of Dear Mark, I cover two topics near and dear to many of your hearts. First, I discuss the interaction between coffee intake and insulin. Does coffee stimulate its secretion? Does it impair insulin’s function, or our body’s reaction to it? Find out how you should approach coffee on a Primal Blueprint eating plan. Then, I explore the suitability of dietary fat in the post-workout meal. Does it belong? Should you be stocking skim milk, de-fatted chicken breast, non-fat yogurt, and cartons of egg whites for your post-workout meals? If you’ve just lifted something heavy, should you therefore shun the yolks and fear the fat for the rest of the day? Find out below.

Let’s go.

Does coffee raise insulin levels? A lot of contradictory stuff out there. Hoping you could get to the bottom of it. Also, how does it affect GABA?



What makes coffee research so confusing is that a lot of it is actually caffeine research. You see, researchers love isolating whole food constituents to avoid confounding variables. It’s easier to get a definitive result about caffeine than it is to get one about coffee, because coffee contains huge and diverse levels of antioxidant compounds. If you don’t, and coffee has a health effect, how do you know if it’s the caffeine or something else in coffee causing the effect? That’s helpful, but most of us are drinking coffee – not popping caffeine pills. So, while caffeine is definitely one of the main active compounds in coffee, it’s not the only one. Adjust your interpretation of “coffee” research accordingly.

That said, both caffeine and coffee have been shown to exert negative effects on insulin sensitivity. Not on insulin itself, though. As standalone substances (without a meal to accompany them), neither caffeine nor coffee have an independent effect on insulin secretion.

But insulin sensitivity, the efficiency with which your body handles incoming glucose? Yeah. Caffeine tends to reduce it. It’s not necessarily a terrible thing, though, when you consider why this occurs. Caffeine increases adrenaline, which increases lipolysis – the liberation of fatty acids from body fat. The increased sense of energy you get from coffee is partly caused by the increased availability of energy in the form of free fatty acids. Of course, an increase in free fatty acids shooting around your body causes a subsequent – and necessary – drop in insulin sensitivity to allow you to actually burn the fat. It all makes perfect sense when you consider the entire picture, but it sounds pretty scary out of context.

Despite all the clinical trials showing that acute intakes of caffeine and coffee tend to reduce insulin sensitivity, the overwhelming majority of the observational literature finds that coffee is linked to lower body weight and protection from type 2 diabetes. Heck, heavy coffee drinking is even linked to protection against non-alcoholic fatty liver disease, an affliction characterized by insulin resistance. And although what I’ve said about correlation and causation in the past holds true in this case (even though it’s supporting something that we might like), the connection is undeniably interesting, especially when you consider that heavy coffee drinking is universally lauded as unhealthy and that habitual coffee drinkers are probably more likely to smoke, stay up late, and eat bad food. Perhaps there is a mechanism there (one suggestion in the NAFLD paper is the antioxidant content of coffee).

Part of it stems from the fact that habituation to a behavior affects the effects of that behavior. You know how once you’ve been drinking coffee for awhile, you don’t really get the “buzz” anymore? You still love (need) the stuff, but it’s not so much a stimulant as it is a normalizer. Well, the coffee buzz comes partially from adrenaline, the secretion of which drinking coffee promotes. Adrenaline is also a potent stimulator of lipolysis, the release of free fatty acids from adipose tissue. Since the liberated fatty acids are causing the temporary insulin resistance, and the fatty acids are liberated by adrenaline, and the adrenaline buzz is lessened with habitual coffee drinking, maybe the insulin resistance is similarly lessened when you’re a coffee fiend. Sounds sensible, right, but what does the research say?

Sure enough, when you give overweight, generally healthy habitual coffee drinkers five more cups a day and measure their “biological risk factors for type 2 diabetes,” things look a little different. Their insulin sensitivity not only stays the same, but their risk factors actually improve. Markers of both liver function and adipose tissue function were improved after upping their coffee intake.

What does all this stuff mean for real world coffee fans?

  • Moderate your carb intake when drinking coffee. Some fruit and maybe even a bit of sweet potato hash can be okay, especially if you’re glucose tolerant, but for the most part, stick to eggs and bacon with your coffee in the morning. And whatever you do, don’t be one of those pudgy carb-loading cyclists clad in spandex I see at the cafe quaffing coffee and pounding kruellers. That’s not a good combo.
  • Get up and move around a bit when you drink. Since that coffee has just liberated a bunch of fatty acids from your adipose tissue, use them! Go for a walk, take a stroll around the office, do some gardening, hit the trails, ride your bike, play with your kids. Just move. If you don’t, the bulk of those fatty acids will simply be recycled back into your body fat.
  • Remember that coffee isn’t just caffeine. It is a whole plant food/drink with hundreds of bioactive compounds beyond just caffeine, like chlorogenic acid, which may have protective effects against type 2 diabetes. Those compounds come from and are affected by the environment, soil, elevation, climate, and region in and at which the coffee was grown. Even the roasting temperature changes the antioxidant content and composition of the beans. The taste and health effects of coffee thusly depend on dozens of factors, and that’s why coffee has different effects on different people as reflected across dozens of studies. Coffee isn’t coffee isn’t coffee. The coffee that tanked those people’s insulin sensitivity in that study may have been a mass market blend from Starbucks, while the single origin coffee from a little Guatemalan plantation could have totally different effects (or it could be the other way around).

Of course, as the ruler of Asgard, father of Thor, and a mighty Norse god, you can probably get away with eating tons of carbs with your coffee (served in a drinking horn, no doubt).

Hi Mark,

I have read somewhere that fat intake is not recommended post workout because it slows the ingestion of protein and carbs. Is it true? If yes, can I take your protein supplement post workout?



Most training blogs recommend that post-workout fat intake be kept relatively low. There are a couple reasons usually given:

  1. If you’re trying to gain muscle mass, you’re going to be eating big after your workouts. Assuming you’re eating a ton of protein and carbs to jack up your insulin levels for the anabolic effect (insulin, after all, shuttles all sorts of nutrients into your cells – protein and glycogen into muscles, for example, after a workout), and your calories are high (to facilitate weight gain) enough, any “extra” fat in the meal has a good chance of being shuttled into fat cells. Thus, from that perspective, fat is “wasted” calories.
  2. If you’re trying to shuttle nutrients into muscle cells, you want insulin as high as it can get, and “everyone knows” that even a modicum of fat will blunt the post-workout insulin spike. Right? Not exactly. One study found that a mixed meal of 47% carbs, 26% protein, and 27% fat – certainly lower fat than most Primal people eat normally, but definitely not a “fat free” post-workout meal – increased insulin levels to 3x fasting at 30 minutes and 5x fasting at 60 minutes (PDF). That’s certainly enough insulin for training adaptations, I’d say. Another study found that post-workout whole milk actually led to greater levels of muscle protein synthesis than post-workout fat-free milk, even though the fat-free stuff had more protein than the whole stuff. Huh, it’s almost like milk is supposed to be whole.

Clearly, some fat after the workout isn’t going to kill you or render your workout useless (and it might even increase protein utilization, at least when it’s consumed as a whole food). And although I’m definitely biased – the fat in my protein supplement (Primal Fuel) comes from coconut milk – coconut milk is rich in medium chain triglycerides, which seems more acutely beneficial to exercise performance than longer-chain saturated fats, at least in rodents.

Stick to the fat inherent in your food – don’t fear meat, fatty fish, and whole eggs – while avoiding dumping copious amounts of butter on your post-workout meal and you’ll be okay.

That’s it for today, guys. Send along any more questions you have and feel free to leave some in the comment section. Thanks for reading!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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