Dear Mark: Food Combining

Steak and TatersFor today’s edition of Dear Mark, I’ll be covering all the different questions I receive regarding the topic of food combining. Now, food combining can refer to different things. First, there’s the dietary philosophy known as “food combining,” which says things like “never eat carbs and proteins together,” or “always eat fruits alone,” or “never, under any circumstances, consume melons with any other food,” or “eat an acidic fruit with your nuts.” It gets very specific and sounds kinda hokey, but I’ll look into it. Then, you’ve got the more general questions around food combinations, such as “does eating fat with carbs promote fat gain?” Many of you are interested in food combining as a general concept. You want to know how to overeat without gaining fat, how to maximize nutrient absorption, and about the specific foods that can change how other foods affect you. I’ll cover those as well.

Let’s get to it, shall we?

Dear Mark,

I have heard two competing ideas on food combining and insulin release/fat storage. One says that you should combine high carb foods with fat or protein to minimize insulin spikes.  The other says that you should eat carbs by themselves because the insulin stimulated by the carbs will also store protein or fat as fat if eaten in the same meal as carbs. Which theory is correct and does it really matter for health/weight loss?

Thank you so much!


For the most part, there’s no need to separate fats from carbs from protein in a normal meal with reasonable amounts of calories. In one study, researchers put patients on one of two hypocaloric diets: either a balanced diet, where fat and protein and carbs were eaten together, or a food combining diet, where macronutrients were consumed mostly separately. Both groups lost the same amount of weight, though people who ate macronutrients together achieved better blood pressure numbers and lost slightly more fat. Those were low calorie diets, however, not massive ad libitum feedings. If you’re eating normal amounts of food (i.e. not stuffing yourself or purposely overfeeding), I see no reason why some sweet potato fries cooked in coconut oil or a bowl of Greek yogurt and berries will do any harm. Your body doesn’t have to handle extra energy, so switching between fuel substrates isn’t much of a problem.

When overfeeding, whether on purpose or inadvertently (the buffet effect), macronutrient selection begins to matter. One of the reasons why I recommend that folks doing a carb refeed for weight loss limit fat for the duration is that overfeeding with carbs boosts leptin and energy expenditure, while overfeeding with fat does not. It’s also why bodybuilders typically follow their workouts with a super high-carb, high-protein meal – to spike insulin and shuttle nutrients into their gaping, starving muscle cells – and go lower carb and higher fat on rest days – to keep fat burning elevated. As a general rule, burning massive amounts of fat precludes burning massive amounts of carbs, and vice versa. Plus, there’s the simple fact that carbs and fat are incredibly tasty together – think pizza, cookies, ice cream, french fries, and so on. Fat alone or carbs alone aren’t very appetizing, but combined they definitely promote overeating. That’s not a problem for people who want to gain weight, or have no issue with incredibly tasty foods, but it bears mentioning. For an idea of the long term effects of a high-carb diet with significant amounts of (bad, refined, seed-based) fat, just look at the obesity rates in America.

I will keep this short. Just a quick question about combining foods to make them more effective or less depending on which we combine. Take local raw honey and ingest it with organic cinnamon in a tea. If the honey causes a slight glycemic rise does the cinnamon reduce that from happening? Given cinnamon’s natural effect on the body’s insulin levels, is this a possibility? Thank you for your time.


When it comes to interactions between specific foods or nutrients, I could go on forever. To keep this post to a reasonable length, I’ll just mention a few.

Cinnamon + Carbs: Yes, you are correct. It appears that cinnamon, which is known to increase insulin sensitivity (even countering the insulin resistance caused by sleep loss), also reduces postprandial blood glucose area under the curve. In other words, having cinnamon with your carbs makes the glucose increase more gradually, rather than spike. Of course, cinnamon isn’t a panacea, judging from the collective body composition of a typical line for Cinnabon.

Vinegar + Carbs: Eating vinegar before or during a carb-rich meal blunts the glycemic response. So, if you have a salad with balsamic vinegar and olive oil dressing before your steak and sweet potatoes, or pickles and sauerkraut before your sausage and potatoes, the blood glucose spike that may have been will be lower and less “spikey” because of the vinegar. Not only that, but vinegar seems to increase satiety and lower insulin in addition to lowering postprandial blood glucose.

Plant Foods + Meat: Although the references are escaping me now, there’s evidence that polyphenol-containing foods, like leafy greens and berries, can inhibit the formation of carcinogens when eaten with meats cooked and seared over high heat. So, there’s a reason salad goes so well with steak, or orange slices go so well with bacon and eggs – they make the meal healthier.

Now, the “food combining diet” questions.

Finally…whats the deal with food combining???? Is it baloney? Should we not have fruits (sugary things) with proteins, etc?


The idea that our digestive systems evolved with a kind of built-in fragility that prevented us from eating different food groups at the same time is preposterous. In a normal, healthy stomach, gastric juice is released on an as-needed basis until the pH hits somewhere around 2. Pepsin – an enzyme geared toward breaking down protein – is also released in the stomach. Then, as the considerable musculature of the stomach churns and mixes the food together, bathing the lot in a wash of stomach acid and pepsin, the small intestine gets the cue to prepare digestive enzymes like lipase (for fat) and amylase (for starch) and more protein-digesting enzymes. When the small intestine begins receiving the first of the chyme (the partially-digested food smoothie your stomach just produced) from the stomach, those digestive enzymes are primed to break down the rest of it.

Here’s the thing about the pancreas: it’s a great multi-tasker. It can secrete lipase, amylase, and protease all at the same time. It can handle a mixed meal containing carbs, protein, and fat with grace and aplomb. Now, if food entered your small intestine in sequential order in its original form, I’d say the food combining folks are on to something. But food enters the small intestine after being churned and blended into chyme. It’s an unrecognizable mix of everything you just ate, not a layer of meat followed by a layer of potato followed by a layer of salad.

There are confounders, of course. If you have low stomach acid, your digestive flexibility may be impaired. If you do not chew your food, instead opting for the gulping method, your stomach will have to work harder to turn it into chyme, and it may fail at that task. If you’re coming off a no- or low-meat diet, your stomach may not be accustomed to producing the required amounts of acid. But that doesn’t mean a normal digestive system can’t handle a mixed meal.

There’s also a funny claim by food combiners that sounds reasonable on the surface yet falls apart under scrutiny: that the acidic environment required for protein digestion in the stomach impairs carbohydrate digestion by amylase, which requires a less acidic environment. It’s true that amylase requires a more alkaline environment. It’s also true that protein digestion requires an acidic environment, and that an acidic environment can impair amylase function. However, it’s also true that the release of acidic gastric juice in the stomach acts as a signal for the pancreas to begin secreting digestive enzymes, including amylase, into the small intestine. In fact, low stomach acid impedes this communication and results in lower levels of digestive enzymes, including amylase, in the small intestine. So, you see, a highly acidic stomach environment is actually essential for proper carbohydrate digestion. And, since eating meat tends to increase stomach acid, it might be even better to eat carbs with your meat.

There has been very little direct research into food combining. That study I mentioned up above, where researchers examined the effects of a “food combining diet” and a “balanced diet” and found that they both elicited similar effects on weight loss (with the normal diet causing an insignificantly greater amount of fat loss), is the only one to explicitly study food combining. While it found no effect on weight loss, it didn’t examine digestion. It may very well be that the food combiners experienced “better digestion,” which is tough to objectively measure, but we can’t say either way.

Hi Mark,

I like to blend fruit and vegetable smoothies in the morning in order to jump-start my greens (and other colors) intake for the day. Recently, I heard from a doctor that eating fruits and vegetables at the same time cancels out nutritional benefits and hurts digestion.

Is there any merit to this “food combining” principle? What about with other foods, like meat?

All the best,


This seems even sillier. Who was this doctor, and what exactly did he or she say? I can’t imagine a physiological mechanism that would make eating spinach and bananas at the same time cancel each other out. The only thing I can think of is that the fiber and oxalates in certain raw vegetables may bind to minerals like calcium, magnesium, and potassium and prevent their absorption and utilization by the body, but that effect doesn’t require food combining to occur. It could happen even if you ate a high-oxalate vegetable by itself, because it would simply bind the minerals present in the high-oxalate vegetable. It doesn’t only affect nutrients from other foods. Besides, as you might recall, all that food gets blended together in the stomach, effectively becoming one.

That’s it for today, folks. Thanks for reading!

I’d love to hear from you guys, if you’ve got any food combining stories, experiences, or pertinent research.

TAGS:  dear mark

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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