Compatible eating

Compatible eating – briefly

Compatible eating is also known as food combining. If you avoid foods that interfere with each other, you digest the meal better. Separating incompatible foods makes it possible to eliminate bloating, excess gas, constipation, diarrhea, stomach pains, and indigestion. If your digestion is healthy, you are healthy.

This idea refers to the books and methods by Dr. William Howard Hay, MD, (“Health via Food“, 1929) and Dr. Herbert Shelton, MD, (“Food Combining Made Easy“, 1952), among others. This first section of this article is a quick, practical overview. The rest of the article explains why this works, including scientific details. This subject, food combining, was taught in medical schools until the 1950s, when it was called  “applied trophology“. To apply this method, both Drs. Hay and Shelton advised:

  1. Drink water, a smoothie, or soup before each meal, and then wait at least fifteen to twenty minutes before eating.  Drink nothing with the meal, except possibly a glass of red wine, if this is already your habit. (Of course, it is even more healthy for many to avoid alcohol.) Why no liquids with the meal? The water lubricates your digestive system before the meal, but it does not dilute your digestive enzymes during and after the meal. 

  2. Eat sweets, sweet fruits, or dessert alone or on an empty stomach (between meals or at least two hours after the end of a meal). Else eat fruits or dessert at the beginning of the meal, and then wait at least another fifteen or twenty minutes. Why? You digest sweets and sweet fruits most rapidly of all foods. So if you eat them at the end of the meal, they are blocked internally by more slowly digested foods. These other foods then either ferment or putrefy,causing inflammation in your digestive system and digestive problems. Sweet foods ferment. Protein putrefies.

  3. Separate (do not combine) starch (bread, pasta, potato, beans, rice, or cereal) and protein (eggs, fish, chicken, turkey, beef, cheese, or dairy) at the same meal. To repeat, even in small quantities, always separate starch and protein at the same meal. Why? Starch requires an alkaline environment with certain enzymes secreted in your mouth and small intestines. Protein requires an acidic environment with other enzymes secreted in your stomach. If you eat starch and protein at the same meal, they interfere with each other for optimal digestion, nutrient absorption, and waste excretion. This interference can cause incomplete digestion, inflammation of the digestive system, fermentation, and putrefaction. Over time, improper food combinations can also cause chronic illness, according to both Drs. Hay and Shelton. 

If you apply these first three steps consistently at every meal for a week, you can begin to improve your digestion. I can almost guarantee it. These first three steps are the complete guidelines to apply this method.

If you forget or if you skip this method for a meal, then restart at the next meal. Many people see results and a loss of weight in one to three weeks, but only if they apply this method meal-after-meal consistently for one to three weeks.

Again, to apply this method, there are only three things to keep in mind at each meal. One, drink water or liquid before the meal (not during the meal), and then wait at least fifteen to twenty minutes before eating. Two, eat desserts or sweet fruits on an empty stomach between meals or at the start of the meal, and then wait another fifteen to twenty minutes. Three, always separate starch and protein. So no toast with eggs, no rice with chicken, and no potatoes with meat. For healthy digestion, it is better to combine the protein with a vegetable, to combine starch with a vegetable, or else to eat the protein alone. So eggs with spinach, chicken with toast, or potatoes with carrots are healthy food combinations for optimal digestion.

The key question to ask yourself is – do I want to eat starch with this meal, or do I want to eat animal protein? You have nothing to lose by trying this. This does not require a change in what foods you already eat, but merely how you compose each meal. If your health is your goal, why not try it? The weight loss is a side effect.

By the way, the separation between starch and protein only applies to concentrated animal protein (with more than 15% protein), such as good-quality, preferably organic, eggs, fish, chicken, or beef. The separation does not apply to vegetable protein, such as tofu, peas, beans, lentils, or other vegetable protein. So rice with beans is proper food combining. The beans have protein, but it is not concentrated animal protein. So if you are a vegan, then this separation of starch and animal protein does not apply to you.

If you are a vegan (HealthViaFood is vegan-agnostic), then you might still try limiting water and liquids to before the meal and limiting desserts to between meals (at least two hours after the meal).

intestines and wheat

Compatible eating – in detail

Of course, the third step, the key step, always separating protein and starch, excludes many combinations you may already be used to, such as eggs with toast or milk with cereal for breakfast, chicken with rice for lunch, and steak with potatoes for dinner. It also excludes most sandwiches, such as ham sandwiches, cheese sandwiches, and hamburgers, since they combine bread (starch) with ham, cheese, or meat (protein).

Substitutes are possible, such as eggs with spinach or eggs with a green salad for breakfast, chicken or meat with steamed carrots or broccoli for lunch, rice with vegetables or a green salad for dinner, or possibly a sandwich with vegetables or avocado only. All of this site’s Recipes combine foods according to this method to separate starch and protein, to drink before the meal only, and to eat desserts between meals. 

Your genes are not your fate. Health is a choice that begins in the mind. Your soul wants you to be healthy. You can start by asking yourself – do I want to eat starch with this meal, or do I want to eat protein with this meal? You then exclude the other from the meal. The choice is yours. What matters more to you – your health or your habits? It is a question of changing your eating habits – for your health. The weight loss is a side effect. By the way, it is not necessary to count calories nor to restrict portion sizes. Many people see results in one to three weeks.

Drs. Hay and Shelton also advised to:

  1. Let vegetables, salads, and fruits (whether citrus or sweet) be the basis of your healthy eating habits. This advice is trite, but bears repeating in a tidal wave of industrial, processed, and packaged foods.

  2. Eat proteins, starches, and lipids (nuts, seeds, and oils) in small quantities.

  3. Eat only one concentrated protein at each meal. This excludes combinations such as ham and eggs, ham and cheese, and beef and cheese (cheeseburger). Why? The required digestive enzymes that you secrete are slightly different for each type of protein. Different enzymes can interfere with each other for optimal digestion.

  4. Eat nuts and seeds (lipids) at the end of the meal, except for a teaspoon of olive oil with a salad or with vegetables. Why? You digest nuts and seeds the slowest of all foods.

Their advice has to do with digestive enzymes, also known as pancreatic enzymes. If you combine your foods according to this method, you may be able to increase excretion of your own digestive enzymes naturally, internally. The main enzymes are pepsin and protease to digest protein, lipase to digest fat, and amylase to digest carbohydrates. Related to food combining, both Dr. Hay and Dr. Shelton further recommended to:

  1. Stay at the table for at least fifteen minutes after each meal. Sit and digest. Why? Let your digestive system absorb the nutrients into your blood. Enjoy the company of any nearby kindred spirits.

  2. Leave at least four hours between meals with starch and meals with protein.

  3. Avoid milk and dairy (pasteurized cow’s dairy), or keep them to a minimum.

  4. cut all refined and industrial foods, except possibly certain fermented foods, such as apple cider vinegar, sauerkraut, miso, or other.
Clker-Free-Vector-Images / Pixabay

The main goal of food combining is to improve digestion. According to this point of view, if your digestion is healthy, especially over time, then you are healthy. What is optimal digestion? It begins with an absence of constipation, bloating, diarrhea, stomach pains, and excess gas. It continues with absorption and assimilation of the nutrients, minerals, and vitamins from your food into your blood, tissues, organs, and bones. Of course, good digestion ends with healthy waste excretion and leads to a healthy weight and healthy ageing.

Try food combining for a week, and see how you feel. You have nothing to lose. Some people notice results in a week or less.

Most of all, the idea is not to mix foods that interfere with each other for digestive enzymes.

For a summary, see the table below.

  1. Optionally mix any food in list A (protein) with any in list B (versatile foods).

  2. Optionally mix any food in list C (starch) with any in list B (versatile foods).

  3. Never mix foods in list A (protein) with foods in list C (starch)).
list A (protein) list B (versatile foods) list C (starch)
eggs green vegetables bread, pasta, cereal
fish most other vegetables potatoes
chicken, turkey nuts & seeds rice
beef, liver olive oil (or flax or coconut oil) sweet potatoes, artichoke 
dairy (goat or sheep) herbs & spices oats, buckwheat, spelt, millet, quinoa
soy, tofu avocado adzuki beans, other beans, chickpeas, lentils, legumes/pulses

If you travel for the day, if you are in a hurry, you could carry some water or herbal tea, an apple or two, a boiled egg or two, and a handful of nuts – to be eaten in this sequence, possibly with a fifteen-minute pause between each course. For example, you could drink the water, then wait fifteen minutes, next eat the apple, then pause, then eat the egg, then another pause, and lastly eat the nuts. Why? You digest fruit most rapidly, then protein less rapidly, and nuts the slowest of all.

Each of these foods requires different digestive enzymes. This sequence also applies to snacks between meals. If you eat out at a restaurant, then you could ask for a meal that includes green vegetables with meat, fish, or chicken, and without bread or potatoes. The vegetables nourish you. Vegetables with meat or fish is a traditional combination in many cuisines in many places. Vegan options include vegetables with rice, potatoes, or tofu, and beans, plus spices. I rarely eat out at restaurants, who tend to try to fill up their customers with starch. I tend to think that I will get a better meals, if I select the ingredients and cook at home.

Why does this work?

The good doctors refer to three factors to explain why this method works:


  • different organs to digest protein and starch, protein in the stomach and starch in the mouth and small intestines,


  • different optimal internal environments (pH) to digest protein and starch, acidic to break down the protein and slightly alkaline to break down the starch, and



  • different enzymes that you secrete to digest protein and starch, pepsin and amylase.

In other words, starch requires certain enzymes, such as amylase, which is secreted in your mouth and small intestines in an alkaline environment. Protein requires other enzymes, such as pepsin, which is secreted in your stomach in an acidic environment. If you eat both starch and protein at the same time, they compete with each for optimal digestion to absorb the nutrients and to excrete the waste.

Different organs

When you start to eat protein, your stomach secretes hydrochloric acid and pepsin to prepare to break down the protein. This was first observed by Dr. Ivan Pavlov, a Russian physiologist, better known for his experiments about conditioning, salivating, and “Pavlov’s dogs”. In 1893, Dr. Pavlov managed to stick a tube in a live dog’s stomach to measure the secretion of hydrochloric acid, a wretched yet useful example of vivisection still common today. He then fed the dog protein and then fed him starch. Soon after the dog was fed protein, it secreted hydrochloric acid in his stomach. After the dog was fed starch, it stopped this secretion, delaying digestion and possibly causing indigestion, even besides having a tube stuck in its stomach.

When you start to eat starch, such as bread, potato, or rice, you to start to break down the starch in your mouth, secreting the enzyme called amylase. You continue to break down the starch in your small intestines. This is a slightly different process from digesting protein. If you eat starch and protein at the same time, the two digestive processes compete with each other internally. Nothing becomes completely digested. The partly digested starch ferments. The partly digested protein putrefies. Partly digested lipids become rancid.

Different pH

You break down protein in your stomach in a very acidic environment. The pH is is between one and five, depending on biochemical individuality. Acid is necessary to break down the protein.

On the other hand, you digest starch first in your mouth and then in a slightly alkaline environment in your small intestines. If you eat both protein and starch at the same meal, the pH is not optimal to digest either the protein or the starch.

Different enzymes

Internally, you secrete hydrochloric acid and pepsin in your stomach during digestion. You convert pepsin to the protease enzyme to digest protein. You secrete amylase first in your mouth and then in your pancreas and small intestines. You use amylase and other enzymes to digest starch. These enzymes can interfere with each other. Continuous interference can have long-term consequences for health.

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Your digestive system is a tube about ten meters long from the mouth to the anus. Of course, food all ends up in the same place, either absorbed into the blood and retained in the tissues and organs, or else excreted in the stool and urine. However, if you combine foods in certain ways, the process of digestion can be much more efficient, avoiding constipation, bloating, excess gas, stomach pains, and indigestion. More efficient digestion consumes less energy and permits better absorption of the necessary minerals, vitamins, and nutrients into your blood, tissues, organs, and bones.

Conmongt / Pixabay

Again, if you combine foods in less healthy ways, the enzymes and organs can interfere with each other. Digestion is incomplete. This can leave your digestive tract impacted with partly digested proteins and fermented starch. Over time, this partly digested food can accumulate and stick to the insides of your digestive system, causing inflammation. This does not need to be. A possible remedy is a change in eating habits according to food combining.

Dr. Hay, the original author, further advised everybody to eliminate white flour, white sugar, and all things that contain them. This is good advice, but it is not directly related to food combining.

Unrelated to food combining, pancreatic enzymes, also known as digestive enzymes, have been used therapeutically by some doctors for many years. This practice goes back to the work of Dr. John Beard and his book, ‘The Enzyme Treatment of Cancer and Its Scientific Basis“, originally published in 1911. More recently, William Donald Kelley, a dentist who  healed himself, and Dr. Nicholas Gonzalez have advocated therapeutic use of pancreatic enzymes against cancer. Do your own research.

Dr. Shelton’s research

Dr. Herbert Shelton MD, author of “Food Combining Made Easy“, measured the relative speeds of digestion of various food types. He found that the following food types are from the fastest to the slowest to be digested, independently of the personal metabolism:

  1. melon (to be eaten separately and first),

  2. sweet fruit, such as banana, grape, raisin, prune, date, mango, persimmon, and cherimoya

  3. sub-acid fruit, such as apple, pear, plum, peach, apricot, blueberry, cherry, fresh fig, and soursop,

  4. acid fruit, such as lemon, lime, grapefruit, pineapple, pomegranate, orange, and kiwi,

  5. green and non-starchy vegetables, such as spinach, broccoli, celery, cucumber, kale, radish, parsley, onion, garlic, collard green, chard, asparagus, turnip, dandelion, Brussels sprout, cabbage, and paprika,

  6. starchy vegetables, such as beet, carrot, sweet potato, artichoke, pumpkin, some squash, cauliflower, and potato,

  7. starches, such as oatmeal, other grains, rice, adzuki beans, most beans, and pasta,

  8. proteins, such as eggs, sardines, other fish, chicken, turkey, beef, dairy, soybeans (tofu), and

  9. fats, such as pumpkin seeds, almonds, walnuts, flaxseed, olive oil, tahini, and avocado.

Dr. Shelton tried to quantify average transit times. On the other hand, what is rapid and healthy digestion for one person may be slow and unhealthy for another. Some people have a naturally more rapid digestion than others. Again, the key is to know yourself and to avoid constipation, bloating, diarrhea, stomach pains, and excess gas. Shelton advised always eating more rapidly digested foods before more slowly digested foods, possibly allowing fifteen minutes between food types, depending on the person and the personal metabolism.

Shelton also advised avoiding sweet fruits and protein and avoiding other more specific combinations of types of fruits and vegetables, such as avoiding sweet fruit and citrus fruit. I do not follow these more specific suggestions. For breakfast, I often drink a smoothie, including a carrot, a cooked beet, spinach, lemon, apple, ginger, hemp seeds or pumpkin seeds, stevia, and water. This mix causes me no indigestion, no diarrhea. It has minerals and vitamins necessary for me. However, my garden is not your garden. This may or may not be healthy for you, depending on your personal metabolism and possibly also on your toxic load.

Biochemical individuality

To repeat, some people tolerate combining different fruits and vegetables better than other people. Some combinations or too much fruits and vegetables at one serving can cause some people diarrhea, stomach pains, or indigestion. When you start to change your eating habits, it is better to start slow and go slow.

If you make only one change at a time, then you can easily reverse this. Others do not tolerate combining certain types of fruits and vegetables at all. Tolerance for this purpose is defined as regular and complete digestion without diarrhea, excess gas, stomach pains, or indigestion. Biochemical individuality may explain why each person has their own digestion. Listen to your body.

Food combining can be confusing at first. For example, a sweet dessert at meal-end, such as chocolate chia pudding made of chia seeds (lipids, also known as fat), cocoa or carob or ginger, and pure stevia, can be a healthy combination, since it has healthy fat, no sugar, and no starch. To keep this simple, you might focus on the first three suggestions at the start of this page.

The two most challenging suggestions to apply are:

  • to separate (do not combine) starch and protein at the same meal and
  • to eat dessert only between meals (not at the end of a meal).

What do you value more – your health or your habits?

superior knowledge about health?The critics

Note that the idea of food combining for healthy digestion has many critics and skeptics. Most of the criticism is theoretical. Most of the critics and skeptics have never read Dr. Hay’s nor Dr. Shelton’s book nor any other book about food combining. None of the critics whom I know have actually tried food combining for themselves. 

The critics point out that people have been eating starch and protein together for a long time, so why is everybody not becoming overweight and ill?

They further point out that many foods, such as grains, beans, and legumes, contain both starch and protein, so separating them is neither possible nor desirable. This is true, but misinterprets the food combining idea, which has to do with more concentrated protein (more than fifteen percent protein content), such as eggs, fish, and meat and starch, such as bread, rice, and potatoes. If you are a vegan, food combining may be useless to you.

The critics are very intelligent and very well organized. They point out that the pancreas can secrete different digestive enzymes, such as amylase, protease, and lipase at the same time, making multi-tasking possible, digesting vegetables, fruits, starch, protein, and nuts in parallel. This is true, but overlooks the point that digestion is only optimal and complete, if the enzymes, organs, and pH environments do not interfere with each other during the process. The result of inefficient, incomplete digestion is that starches ferment and proteins putrefy and accumulate in the walls of the digestive system. Repeated, continuous incomplete digestion can also result in constipation, bloating, diarrhea, stomach pains, excess gas, and weight gain, depending on the person.

The critics often try to ridicule the idea of “better digestion”, which they claim cannot be measured. Naturally, you, and only you, can evaluate your own digestion, optimal, sub-optimal, efficient, inefficient, bloating, gas, stomach pains, heartburn, diarrhea, constipation, or healthy, regular excretion. If your digestion is healthy, or if you make it become healthy, especially over time, then you are healthy. This is an ancient idea.

Lastly, the critics point out that no clinical trial has ever been done to prove that food combining is safe and effective. Nothing prevents you from doing an experiment on yourself (n=1), trying food combining and then drawing your own conclusions for your own health. It will not cost you anything more than what you are already paying for food to try it. It does not require you to change what you eat, but merely how you compose each and every meal. You could try it for a week or two or three and then see how you feel.

Regarding published science, no clinical trial has ever been done to prove that water is a cure for extreme dehydration nor that prunes have a laxative effect, yet we all know that these are true. As Dr. Shelton said, “look for the truth, and your health will follow.” The truth does not always conform to the opinion of the majority. Skepticism is healthy, but let us not overlook the simple facts (different organs, pH, and enzymes) and also biochemical individuality to explain why this method already works for many people.

Vegan or paleo?

Nota bene. Food combining is both vegan– and paleo-friendly. In other words, it applies to both vegan and paleo eating habits (or ketogenic, macrobiotic, Gerson, or Budwig), your choice. It is possible that the more rapidly you digest naturally, then the more healthy it is for you to separate starch and protein at the same meal.

For example, ectomorphs tend to have thin bones and long shapes. They also tend to digest more rapidly than mesomorphs, who tend to have bigger bones, more rounded body shapes, and slower digestion. Food combining may be ineffective or less effective for vegan mesomorphs who eat  grains, beans, and legumes, such as oatmeal, rice, and beans. This concerns biochemical individuality, another topic

Do you know your ABO blood type? After food combining, you could also apply blood type eating, another idea for health via food. Food combining may be more useful for blood type O than for blood type A. If you have blood type O, you tend to digest animal protein (meat, fish, or eggs) and fats (nuts, seeds, and oils) more effectively than blood type A. O types tend to excrete more of the enzyme alkaline phosphatase, which is required to digest fats, such as nuts, seeds, and healthy oils.

Individual interpretations

Many authors have written on the subject of food combining. Naturally, they each tend to have their own point of view based on their own experience, observations, and biochemical individuality. The original scientific references are the books by Drs. Hay and Shelton. These books and ideas have withstood the test of time. Hay also wrote about the acid-alkaline balance, another idea for health via food. Years ago, while Hay was alive, food combining was called the “Hay diet“. It is not a diet in the sense of temporary restrictions. It is a way to compose meals, most of all avoiding starch and protein at the same meal. In this twenty-three-minute video, Dr. Mercola and Dr. Pickering discuss food combining. Proper food combining can possibly eliminate yeast and fungal infection.


For healthy digestion, food combining works for many people, including me. Both Dr. Hay and Dr. Shelton reported using this method to cure many, though not all, of their patients of chronic illness. If you doubt this, then read their books online. Do your own research. If you have digestive problems or discomfort, I suggest that try food combining and then see how you feel. You have nothing to lose. Food combining can even be cheap. Many people see results in one to three weeks.

What do you value more – your health or your habits? 

Scientific references

Hay MD, Dr. William Howard, “Health via Food“, Sun-Diet Health Service, 1929 
Shelton MD, Dr. Herbert, “Food Combining Made Easy“, 1952
Grant, Doris, “Food Combining for Health“, Harper Collins, 1987
Marsden, Kathryn, “Food Combining“, Piatkus, 2005
Walb MD, Dr. Ludwig, “Original Haysche Trennkost“, Haug, 1987 (in German)
Haas MD, Dr. Elson, “Food Combining” article, his website, flowchart
Le Tissier, Jackie, “Food Combining for Vegetarians“, Thorsons, 1992
Habgood, Jackie, “The Hay Diet Made Easy: A Practical Guide to Food Combining“, Souvenir Press, 1997

Wright MD, Dr. Jonathan, “Why Stomach Acid Is Good for You“, M. Evans, 2001
Beaumont MD, Dr. William, “Experiments and observations on the gastric juice, and the physiology of digestion“, 1833
Mayer MD, Dr. Emeran, “The Mind-Gut Connection“, Harper Wave, 2016, video

Hyman MD, Dr. Mark, “Why Fixing The Gut Is The Key To Healing Chronic Disease“, one-hour video
Hyman MD, Dr. Mark, “Why Food is Better than Medication to Treat Disease“, eighty-two minute video
Ioannidis MD, Dr. John, “Why Most Published Research Findings Are False“, PLOS, August 2005

Application of food combining principles“, T.C. Fry, 1:25 video, Health Sciences Institute
Physiology that decrees correct food combining“, T.C. Fry, 1:08 video, Health Sciences Institute
T.C. Fry, “The Life Science Health System“, 1-54 lessons read by Kaz the Q Lady, book, vegan manifesto, pdf

Bristol Stool Chart, Bladder and Bowel Foundation, Solihull, UK

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