Heard of Food Combining? Get a Dietitian’s Take.

Just like every other trendy diet, food combining promises some pretty amazing things. But also like every other trendy diet, if it sounds too good to be true, it probably is. Before you print that food combining chart off Pinterest and start changing your eating habits, it’s important to know that not only is there no science to support food combining, but a lot of “forbidden” food combinations are actually great for your health.

What is food combining?

Food combining is a diet that essentially claims that the macronutrients we consume—fat, protein , and carbohydrate—should be eaten separately to maximize digestion. It’s hard to pin down one source that lays out the official food combining rules, but you can find plenty of food combining charts and blog posts online if you search for them. They vary a bit, but all of them give meal suggestions and advice including: only eat fruit on an empty stomach, never combine protein and carbs, and fat inhibits the digestion of protein. Luckily, leafy green salads pair perfectly with every meal; but also, you shouldn’t drink liquids with or immediately after a meal.

“It’s definitely not a new diet,” says Brit Trainor, M.S., R.D. , a health coach at Parsley Health. Its roots are in ayurvedic medicine, so the principles have been around for a while, she adds. But over the past few years, it’s become more popular, thanks to social media.

Does food combining really work?

“There really isn’t any research to support the digestive or health claims that fans of food combining make,” says Trainor. One study conducted back in 2000 looked at the weight loss claim in particular and found that food combining didn’t result in any additional weight loss compared to a balanced diet of the same caloric intake.

When it comes to the digestion claims, Trainor is clear that our bodies are built to be able to digest a mix of macronutrients at the same time. “The majority of foods that we eat are already mixed in terms of macronutrients. For instance, vegetables and grains contain both protein and carbs, nuts contain protein and fat, and dairy contains all three. Food combining doesn’t make sense if you have to separate everything because most foods are a combination,” Trainor says.

Here’s how digestion actually works: “Carbs start to be digested in the mouth by a protein called amylase,” says Trainor. “Then, when food gets to your stomach, gastric acid is released, and the digestive enzymes pepsin and lipase start to digest protein and fat. In fact, even if there is no protein or fat in your food, research has shown that pepsin and lipase are still released . It’s almost kind of like your body is anticipating a mixed meal even if it’s not,” Trainor explains. In the stomach, all this food is mashed up and mixed together (into a substance called chyme) before it moves into the small intestine. “It’s not like one thing comes first, everything kind of goes together and blends together,” says Trainor. Next, the gastric acid from the stomach is neutralized, and the intestines are flooded with more enzymes to further break down carbs, fats, and protein, she explains.

“There’s no need to think the body has to choose between which food to digest. Things won’t get stuck in your digestive system, it’s just not how it works,” Trainor says

There’s also no truth to the claim that foods with different pH levels can’t properly be digested at the same time, another claim of food combining. Again, your digestive system is ready for that. “If you eat a really acidic or alkaline meal, your digestive system is set up to just add more or less digestive juices in order to maintain the necessary pH level,” Trainor says. If you do have a hard time digesting certain foods, you may benefit from taking a digestive enzyme—some people need a little more support than others, Trainor adds. “But for the most part, the body is designed to do what it does and it does it very effectively.”

Of course, a food sensitivity or allergy can also make it hard for you to digest certain foods. But in that case, food combining isn’t going to help you—figuring out what’s problematic for you and cutting it out will. If you eat too much of one food, like fiber or fat, you may end up feeling bloated and uncomfortable as it digests. Again, it’s not because you ate those foods with fruit or protein, it’s because you overate a certain nutrient.

The mental toll of food combining

Trainor also notes that following a strict eating plan like the food combining diet could cause some psychological stress as well. “If you get into that mindset that only certain foods can be eaten with certain foods and set all these different rules with food, it can really have a negative impact on your relationship with food,” Trainor says. “Anytime there are a ton of rules around food, I just get a little nervous.”

Foods you should pair together

The best way to aid digestion is to eat a healthy, balanced diet. That means eating fat, carbs and fiber, and protein—all at the same meal. By combining macronutrients, you can feel fuller for longer and get the appropriate diversity of nutrients, says Trainor. “Most importantly, it helps keep blood sugar balanced,” Trainor says.

When you eat carbs alone, you get a blood sugar spike that ultimately ends with a crash, leaving you feeling hungry 30 minutes to 2 hours later. Even fruit and other sources of healthy carbs (like veggies) are still going to be broken down into sugar. “But if you combine carbs with a protein or healthy fat, which takes longer to digest, that helps keep it from digesting super quick and it’s going to help blunt the glucose effect and keep you fuller for longer,” Trainor explains.

There are also a few nutrients that, when paired together, can be more readily absorbed by the body, says Trainor. Vitamin C and iron is one such pairing—which would also be a no-no if food combining rules were legit. Iron comes in two forms, heme in animal products, and non-heme, which is plant-based, Trainor says. “We’re a lot less likely to absorb non-heme iron, which can be problematic for vegetarians.” Pairing vitamin C-rich foods like citrus fruit or red pepper with foods containing non-heme iron—plant foods like whole grains, nuts, seeds, legumes, and leafy greens—makes the iron more absorbable, says Trainor. Yes, we’re saying it’s OK to eat fruit with other foods. Your body will appreciate—and thrive off—the variety.