Food combining is a method of eating that only allows for certain food combinations in an effort to support digestion and overall health. But is there any truth to the claims and the rules of food combining? Here is everything that you need to know about food combining and whether it makes a difference or not.

What is food combining?

Food combining is a style of eating that only allows for specific food combinations. The concept is based on the claim that different foods digest at different rates, have different transit times in the GI tract, and require different pH environments: proteins need an acidic environment to be broken down, whereas carbohydrates require an alkaline environment. Proponents of the food combining diet suggest that the consumption of protein-rich foods with carbohydrate-rich foods promotes gas, bloating, poor digestion and, therefore, poor absorption of nutrients. Based on these theories, food combining diets recommend consuming certain foods on their own or in specific combinations for “optimal digestion”.

Food combining principles are largely rooted in the practice of Ayurvedic medicine, were more widely introduced in the 1920s by physician William Howard Hay, creator of the Hay Diet, and have recently become re-popularized by celebrities, social media influencers, and YouTubers. (1)

The Food Combining Rules

Although there are different variations of food combining diets, the general concepts and rules are the same:

• Always eat fruit alone or on an empty stomach,
• Do not combine proteins with starches,
• Eat starches alone or with non-starchy vegetables,
• Eat meat, dairy, fish, and eggs with non-starchy vegetables,
• Eat nuts, seeds, and dried fruits with raw vegetables.

In fact, depending on what protocol you follow, there are detailed charts designed to guide you through recommended food combinations. (2)

The Claims

The primary proposed benefit of the food combining diet is that it will make digestion more “efficient” and, therefore, improve nutrient absorption, improve gut health, alleviate digestive symptoms and improve detoxification. Advocates of the diets claim that:

• Consuming proteins, starches, and/or fruits together will cause digestive symptoms and impair nutrient absorption,
• Improper food combinations can also “confuse” the body given different foods require different enzymes to be digested,
• Poor food combining will slow down digestion and increase the build-up, fermentation, and release of “toxins”,
• Proper food combining allows the stomach to maintain proper pH balance and enzyme production,
• Proper food combining requires less energy by the body to digest food,
• Proper food combining can promote weight loss.

It is also believed that poor food combinations can promote disease and illnesses.

Is food combining science-based?

Unfortunately, science does not support the claims of food combining. In fact, the theories presented largely ignore the biology of the human body and the digestive system.

Digestion is a complex system made up of numerous parts that work together to break down, digest, absorb, assimilate and defecate the food that we consume. The components of the digestive system work in unison using a top-down approach where each step triggers the next. Contrary to the theories proposed by advocates, the food we consume does not just “mix” in the stomach, it travels through our digestive tract passing through the mouth, esophagus, stomach, small intestine, large intestine, and anus while triggering reactions from our liver, pancreas, and gallbladder along the way. (3)

In fact, very little digestion occurs in the stomach. The process of digestion actually begins in the mouth, as the smell of foods helps to trigger the production of our salivary enzymes and the process of chewing our food stimulates the production of amylase, the enzyme required for the digestion of carbohydrates. (3)(4) As food continues to move through the digestive tract and into the stomach, gastric juices are released to help break down protein and the highly acidic environment kills any microorganisms in the food and, combined with the action of the enzyme pepsin, results in the catabolism of protein in the food. During this process, the stomach acts as a “holding tank”, churning food to chyme before it enters the small intestine where the acid from the stomach is neutralized and the nutrients from our food are further digested and absorbed into the bloodstream. (4) Only a small amount of chyme is released into the small intestine at a time. As it does, the liver secretes bile to help break down fats and the pancreas releases enzymes to further break down carbohydrates, protein, and fats. (4)(5) Therefore, contrary to the theories presented by food combining diets, the human body’s digestive tract is a complex and hard-working system that does not need to choose between digesting proteins, starches or fats.

Moreover, the idea that combining certain foods will “disrupt” the pH environment is misguided and misunderstood. Although it is true that certain enzymes require specific pH environments to function optimally, the consumption of more alkaline or acidic foods does not significantly change the pH of your digestive tract. Not only do enzymes function in different areas of the digestive tract but the acidity level of your digestive tract is controlled by the body’s own sensors. Although the stomach itself is a very acidic environment, with a low pH of 1.5 to 2, it becomes acidic when any food enters the stomach, not just protein. (4) This acidity kills microorganisms, breaks down food tissues, and activates digestive enzymes. As food moves from the stomach to the small intestine, the pancreas releases enzymes with an alkaline solution rich in bicarbonate that neutralizes the acidity of chyme from the stomach, which activates the enzymes to break down starches, disaccharides, proteins, and fats. (4) The pancreas actually releases these enzymes in response to the drop in pH when the acidic stomach contents enter the small intestine. Ironically, the more acid your stomach produces the more alkaline your pancreas response will be, making it an ideal environment for both the digestion of protein and carbohydrates. (5)(6)

As for fermentation and the build-up of “toxins”, thanks to its acidic environment, fermentation does not occur in the stomach. The area where fermentation does occur in the digestive tract is in the large intestine, where it is a good thing. The natural fermentation of undigested carbohydrates, specifically prebiotic fibre, allows for the creation of trillions of beneficial bacteria known as probiotics, which have shown to be incredibly beneficial to our health.

And finally, there is no evidence to show that food combining in any form supports weight loss. One study did compare the effects of a “food combining diet” and a “balanced diet” it found that both diets elicited similar effects on weight loss. (7) The physiology of weight loss is based on a calorie deficit, not a specified eating style or combination of foods. Therefore, in order to support a goal of weight loss while following a food combining diet, one must still maintain a calorie deficit.

Benefits of Food Combining

Promotes Whole Foods

Generally speaking, food combining promotes a diet of whole foods, which is ideal for overall health. Although it does not allow for certain combinations of whole foods it does promote their consumption.

Drawbacks of Food Combining

Can be Restrictive

Given the rules and guidelines, food combining is a restrictive way of eating. Learning the rules and taking the time to implement them at mealtime can become very tedious and time-consuming, and may promote disordered eating behaviors.

Ignores the Complexity of the Digestive System

The claims made by the food combining diet largely ignore the complexity of the body and digestion. The digestive system is a complex system that is designed and equipped to process different macronutrients at the same time. The human body evolved consuming various combinations of foods and macronutrients, influenced by geography, religion, and culture, which has allowed the digestive system to evolve with the ability to digest various food combinations.

No Scientific Evidence

Although proponents of food combining make many claims about its health benefits, there is currently no scientific evidence to support them. Not only does the biology of the digestive system not support the claims that different foods require different digestive environments but there are no studies to support the proposed benefits of food combining.

So, does food combining work?

There has been very little direct research into food combining and there is very little evidence to support the food combining claims. The human body evolved eating whole foods and the digestive tract is a complex system designed to multi-task and digest a wide variety of foods and macronutrients at one time.

Moreover, almost all whole foods contain a combination of macronutrients; most proteins contain a combination of protein and fat; while beans and lentils contain a combination of starch and protein; and whole grains, nut, and seeds contain a combination of starch, protein, and fat. Therefore, the suggestion that macronutrients need to be consumed individually or in specified combinations is simplistic at best, nor does it allow for the basic physiology or biology of humans, animals, or plants.

The Bottom Line

At this time, there is very little evidence to support the claims that food combining improves digestion, promotes weight loss or decreases the potential for disease. If an individual feels that the food combining rules work for them, they can certainly follow them, however, there is no benefit or need for everyone to do so.