Validating the 4Leaf Survey

So it can become the most important vital sign in medicine

617 jpeg 4Leaf Logo

The healthfulness of what we’re eating. We believe that the vital sign we need should be a person’s 4Leaf score. Without a doubt, the future of medicine will include a great deal of focus on what we put at the end of our forks. In fact, it has already begun in many parts of the world. In New York City, Arizona, Australia, North Carolina, Florida, California, Canada, China, Ireland, The Netherlands, Italy and in the Finger Lakes Region of New York state, that process is well underway.

Many primary care physicians who are fed up with “disease management,” are embracing a whole new way of practicing medicine. They are now harnessing the power of food to reverse disease and promote health.

And those physicians are discovering that our powerful 4Leaf Survey is quickly becoming the most important tool in their bag. Dr. John Green in Australia says that he uses it ten times a day and that he could no longer live without it. Why is this tool so important to him–and to others, like Dr. Kerry Graff, shown here? As she explains, there are three reasons:

Kerry Graff, MD

Kerry Graff, MD, co-author of the 4Leaf Guide to Vibrant Health

  1. “It’s easy, fast, accurate and does a great job of engaging the patient in the process of improving their own health.
  2. The patients can easily see (from the printed version of the survey) exactly where they lost points and how they can easily turn those negative points into positive points.
  3. By just following the computer-generated results and emailed report, millions of patients can now learn how to improve their health–with or without the aid of a physician.”

But what about validation? How do we know that it is accurate? How do we know that it really works? That is exactly what I will try to explain here.

A little background. Our 4Leaf concept and the accompanying 4Leaf Survey both evolved over a period of five or six years–from 2010 to 2016. I started out wanting to develop a simple survey that would assess a person’s diet compared to Dr. T. Colin Campbell’s definition of an optimal diet:

“The closer we get to eating a diet of whole, plant-based foods, the better off we will be.” — T. Colin Campbell, PhD

As with Bill Clinton, this book will allay the Pope's fears about the quality of a plant-based diet.

Scientific proof that people who eat more whole plants are the healthiest people on Earth

In 2009, I reviewed the concept of six levels of eating with Colin at his breakfast table in Ithaca. He loved it because it was positive and emphasized the maximization of the best food—not just the avoidance of meat, dairy, etc. The idea was to have the bottom level being the SAD, with an estimated LESS than 10% of calories from whole plants. The next level is “Better than Most” — with an estimated 10 to 20% from whole plants.

The 1Leaf level is 20 to 40, 2Leaf is 40 to 60, 3Leaf is 60 to 80 and 4Leaf is over 80% of one’s daily calories from whole plants.

Elegantly simple and amazingly powerful. Our simple, quick and easy survey enables us to estimate the level at which a person is currently eating. As we know, the SAD level will likely include at least 65% of the population with another 25% at the BTM level. That covers 90% of the population and, if they are honest in their answers, they will all have trouble scoring 1Leaf or better.

Our 4Leaf system features a scale where the individual chooses how far up the scale they wish to eat. After giving the survey well over 100,000 times, we have concluded that it will accurately and consistently put people in one of three buckets–defined here:

Bucket #1. Unhealthful Diet and “Better than Most.” In this bucket, it really doesn’t matter at which level someone scores, the advice is the same. “Replace most of your animal-based and highly processed foods with whole plants.” (90% of the USA population will begin their journey in this bucket.)

Bucket #2. Fairly healthy. 1Leaf and 2Leaf levels. Eating better than 90% of the population, these people are eating far better than the average American. But many of them just need to understand that they don’t EVER “need” to eat any animal protein, even from fish. (People at this level are well on their way to an optimal diet.)

Bucket #3. Very healthy. 3Leaf and 4Leaf levels. Representing less than 5% of the population, these folks are already eating a superior diet that will likely reverse heart disease, diabetes and many other diseases, including some cancers.

Taking the 4Leaf Survey online can happen anywhere--anytime.

Taking the 4Leaf Survey online can happen anywhere–anytime.

The main advantages of our online 4Leaf Survey (and overall system) is that it is quick, easy, flexible, non-judgmental AND is based on each person’s answers. It engages them in the process and shows them exactly what they should do to improve their score and their health.

Again, what about validation? The short answer is that so far there has been no formal validation process. At first, we concluded that there were two things we would like to validate and a few years later, we added a third. Here are the first two:

1. That the score accurately determines the percentage of calories from whole plants. I discussed this with Dr. Campbell and we agree that it would be near impossible to PROVE that it does. There are just too many variables involved (beginning with levels of honesty in reporting). And if you tried to design a survey that addressed all those variables, it would almost surely be too complex and too cumbersome to be effective.

2. That patients who are coached “with” the 4Leaf Survey are more successful than those who are not. I also discussed this with Dr. Campbell and a few medical doctors who are using it in their practices. Based on early anecdotal evidence for the past few years, there is no doubt in my mind that we can validate this. And, while we’re completing that validation process, we know for certain that using the survey cannot hurt anyone and that it is already helping millions. People everywhere seem to like the survey and they LOVE what it helps them do for their health.

We already know that, without formal validation, our survey is helping lots of people move away from animal-based foods, while adding a lot more whole plants to their diets.

Conclusion. Our 4Leaf model is simple and that’s why it’s so effective. The possible scores range from -44 to +44. And here’s what we know about those scores, assuming that the responses are truthful:

  1. A net score of +44 would mean zero animal products in the diet and a net score of -44 would mean zero whole plants in the diet.
  2. People with net scores greater than +10 are eating a fairly healthy diet–consuming far more whole plants than the average American.
  3. People with net scores less than zero include the majority who are eating the Standard American Diet (S.A.D.) and those who are still eating more animal-based calories than whole plant calories.
  4. That’s it! The survey helps the majority of the folks in #3 above see where they lost points and how they can improve their diet by adding more whole plants–replacing some (or all) of their animal-based and highly processed foods.
T. Colin Campbell, PhD, Nutritional Biochemistry, Cornell

T. Colin Campbell, PhD, Nutritional Biochemistry, Cornell

Powerful words from T. Colin Campbell. In September of 2015, he sent me a very strong endorsement of our simple, but effective, 4Leaf model. He emailed it from from a conference featuring fifty of the world’s top cancer researchers:

“Your 4Leaf model is one-hundredth the complexity but has real value that may exceed any of the very comprehensive survey models developed by some of the world’s top cancer specialists.”

J. Morris Hicks, working daily to promote health, hope and harmony on planet Earth.

J. Morris Hicks, working daily to promote health, hope and harmony on planet Earth.

Given the nutritional science preeminence of this great man, I would say that his statement alone constitutes a pretty solid validation of the 4Leaf Survey and its related tools.

Here’s that 3rd form of validation. In May of 2018, I added an alternative way of thinking about validation. I suggested that that, by definition, the The 4Leaf Survey has already been proven valid–for what it was designed to do.

How so? Let’s begin with the extremes:

1. People who eat ZERO whole plants. They get zero + points on the first four questions, which means that their entire diet is comprised of animal based and/or processed foods. They will more than likely score somewhere between -21 and -44, which is the range for the “Unhealthful Diet” (UD) level of eating, more than likely deriving less than 10% of their calories from whole plants.

2. People who eat nothing but whole plants. As such, they get zero “minus” points in questions 5 through 12 so their entire score depends on just the whole plant foods in questions 1 through 4 (categories where they ALL of their calories). Hence, they will almost certainly score at +30 points are better–which is the 4Leaf range of our 88-point scale.

Now that we’ve covered the extremes, all we need to do next is divide the remaining possible scores, from -20 to +29, a total of 49 points, into the other four groups: Better than Most, 1Leaf, 2Leaf and 3Leaf. That’s what we’ve done with our 4Leaf scale and I now believe that we can rest our case that the numerical score ranging from -44 to +44 is a fairly reliable indicator (data-based estimate) of the percentage of one’s daily calories that is comprised of whole plants.

It’s not precise, but it doesn’t need to be. It’s kind of like sailing. You don’t need to know the exact velocity of the wind (speed and direction) in order to be a great sailor. You just need to know how to set your sails for the general direction you want to go–then make adjustments as you go along.

This conclusion is reinforced by the fact that, over the past six years, we’ve received a great number of unsolicited kudos about the survey compared to less than TEN complaints after hundreds of thousands of iterations. That tells me that this survey has passed the test of time and should be used with confidence.

The Bottom Line. Our 4Leaf Survey does a great job of identifying the 90% of the Western population who need a lot of help in understanding what comprises an optimal diet for humans–one that is effective in truly promoting health.

These are the billions of people who will score at the UD or the BTM level on the 4Leaf Survey. If they are honest about what they’re really eating, their score will not reach the single digits of the 4Leaf scale.

And the 4Leaf advice to all of those billions of people is always the same:

 “Work on replacing most (if not all) of your animal-based and highly processed meals & snacks with whole, plant-based foods.”

What about risk? I have concluded that there is absolutely zero risk in using the 4Leaf Survey–yet there is a great deal of upside potential. I am talking about the desperate need for a rapid, global dietary shift toward widespread consumption of whole plant-based foods–for our health, for our environment and for our future as a species.

The 4Leaf Survey was not designed to be precise and doesn’t need to be precise to be effective. It just needs to enlighten the user to the fact that they are eating nowhere near the healthy diet that they think they are eating. Dr. Kerry Graff (my co-author) has found the survey to be a very effective tool for actively engaging her patients in the process of making huge improvements in their diet. Often, after completing their first survey, they exclaim:

“Oh my God, I thought that I was eating a pretty healthy diet!”

After just turning a few of their routine meals into super-healthy 4Leaf meals, those patients will receive some positive reinforcement in the form of a higher 4Leaf score the next time they take the survey.

Please email me directly at if you have any comments or questions. If you are a medical practitioner, perhaps you would like to assist in the validation process with your own patients. With your help, we can change the world with this simple, yet powerful, tool.

Here are a few links that you might find helpful:

  1. Printer-Friendly 4Leaf Survey in English
  2. Links to all 12 versions of the survey in 8 languages
  3. Take the survey at
  4. Take the survey at the eCornell website
  5. Kids 4Leaf Survey
  6. Introduction to 4Leaf
  7. 4Leaf Improvement Tools
  8. Begin by Making a Commitment to 4Leaf
  9. Meal Planning for the 4Leaf Lifestyle
  10. Letter that may help your doctor understand 4Leaf
  11. 4Leaf Score–the Next Vital Sign in Medicine
  12. Finally, the 4Leaf Survey Validation Process

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