What is the Healthiest Diet?

A scientific approach to identifying the healthiest diet. Updated September 28, 2021.

Before we begin I’d like to present this question: if right now, you could only choose one diet that will stay with you for the rest of your life, would it be the one you’re on right now?

Why is this important now?

Human health is in a crisis. Many disease rates are at all time highs, and continuing to rise while the US is spending more of its GDP on health care every year. The statistics are alarming.

  • 1:2 Cardiovascular Disease
  • 1:2 Cancer
  • 1:4 Stroke
  • 1:10 Diabetes
  • 40% Obesity
  • 1:5 Mental Illness
  • 1:40 Autism
  • 1:10 Alzheimer’s
  • 1:10 Attention Deficit

While it seems like poor health is a natural part of life, especially for Americans, human health does not have to be so plagued by disease as it is now. We can live healthier lives without all the unnecessary suffering.

The purpose of this presentation is to help me and others gain some insight from the confusing mess of information surrounding health and diet. By no means is the information in this blog post accurate, but I can assure you that it is my best effort at this point in time. At the end of the day, whatever you conclude, hopefully you will learn at least a thing or two. With that said, have an open mind and let us try to uncover the relation between human health and diet.

So to begin, how do we start to tackle such a difficult problem? We can begin by identifying the question we should ask, which would be asking the broadest question possible; this is no easy task. I think we can all agree that the big question is (or at least should be)…

How do we be healthy?

That’s it. It may seem rather straightforward, but surprisingly you may realize that your big question is really how do I lose weight, how do I build muscle, how do I get rid of <insert disease>, or even how do I prove him/her wrong? Anyways, now that we have identified the big question we can break it down by specifically asking the question: 

What diet is the most healthy?

Although the key to health is more than just diet, diet is arguably the single most important factor. We will tackle this one question.

Before we continue, let us define the terms healthy and diet. We will define healthy as maximum lifespan with as few diseases as possible and diet as the food we eat everyday.


Now that we have identified the question, we can begin by asking how? How do we figure out what the best diet is that will enable us to be healthy?

Let us list some methods as to how we can approach this question:

1. Conduct studies comparing the diets

2. Conduct studies on specific types of food

3. Assume that people at some point in the past were healthier, then identify their diets

4. Observe who the healthiest people are currently and identify their diets

The list goes on, but most methods follow one of these listed.

Bad Methods

Now just for fun we can make a list of bad methods:

1. Assume something without good evidence

2. Follow trends

3. Listen to someone whose bottomline is not your health

4. Continue something out of habit

5. Continue something because you like it

Defaulting to a bad method is easy, while using a good method requires effort. 

Hierarchy of Evidence

Before we get into each specific method, we should first understand some basic concepts about evidence. Not all evidence can be weighed equally. Some forms of research are higher quality and less prone to error than others. For example, animal studies and case reports are weaker than cohort studies and randomized controlled trials (RCT). In addition, sample size, duration, study design, and other factors all contribute to the strength of a study. 

In order to arrive at an evidence-based conclusion, we must do a thorough review of the literature and prioritize higher quality research. Now let’s delve into each method.

Method 1

Method: Conduct studies comparing the major diets such as vegan, vegetarian, paleo, keto, low-carb, mediterranean, etc

Thoughts: A large randomized controlled trial comparing the diets over a long duration would give us a definitive answer to the question. However, this is nearly impossible to conduct. Therefore, most studies using this method are observational and prospective.


  1. Adventist Health Study 2
    1. Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4191896/
    2. Vegetarian diets and incidence of diabetes in the Adventist Health Study 2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638849/
    3. Vegetarian diet and blood pressure among white subjects: results from the Adventist Health Study-2  https://pubmed.ncbi.nlm.nih.gov/22230619/
    4. Association between vegetarian diets and cardiovascular risk factors in non-Hispanic white participants of the Adventist Health Study-2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391580/
  2. Vegetarian Diets and Blood Pressure A Meta-analysis https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1832195
  3. Association between plant-based diets and plasma lipids: a systematic review and meta-analysis https://academic.oup.com/nutritionreviews/article/75/9/683/4062197
  4. Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults https://pubmed.ncbi.nlm.nih.gov/28728684/
  5. Taiwanese Vegetarians and Omnivores: Dietary Composition, Prevalence of Diabetes and IFG https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3921224/
  6. Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies https://pubmed.ncbi.nlm.nih.gov/26853923/
  7. China-Cornell-Oxford Study by T. Colin Campbell

Conclusion: People on whole-food, plant-based diets have lower all-cause and cause-specific mortality than people on animal-based diets.

Method 2

Method: Conduct studies on specific types of or nutrients in food and determine whether they increase or decrease disease, mortality, or some measure of health

Thoughts: This method takes a more indirect approach by analyzing the individual components of a diet such as saturated fat, red meat, oil, whole grains, carbohydrates, eggs, etc. 


  1. Meat intake and mortality: a prospective study of over half a million people https://www.ncbi.nlm.nih.gov/pubmed/19307518
  2. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality https://www.ncbi.nlm.nih.gov/pubmed/27479196 (most downloaded article of 2016 in JAMA)
  3. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality (2020) https://preview.thenewsmarket.com/Previews/JOUR/DocumentAssets/444168.pdf
  4. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality in a Japanese Cohort https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2748453
  5. Associations of Dietary Cholesterol or Egg Consumption with Incident Cardiovascular Disease and Mortality https://jamanetwork.com/journals/jama/fullarticle/2728487 
  6. Association of Frequency of Organic Food Consumption With Cancer Risk https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2707948

Conclusion: Meat consumption is associated with higher mortality, while plant consumption is associated with lower mortality. Also, there may be an association with organic food consumption with lower cancer risk. However, it is important to include studies on the other types of food such as fat, sugar, eggs, and oil in determining the healthiest diet.

Method 3

Method: Assume that people at some point in the past were healthier, then try to identify what their diets were

Thoughts: This is not an evidence-based method because we cannot obtain data. I included it as one of the main methods because of its wide prevalence. How do we identify the thousands of different foods they ate, and measure the quantities of each food? How do we get reliable data on their diseases and lifespans?


  1. Paleo

Conclusion: While there is some value to its principles such as eating no processed foods, this method is inferior to other methods. It relies on speculation rather than science.

Method 4

Method: Observe who the healthiest people are currently, then find out what their diets are

Thoughts: Similar to method 3, this method assumes that there are healthier people. But unlike method 3, we are able to get data because the populations exist. 


  1. Blue Zones Studies by Dan Buettner https://www.bluezones.com/recipes/food-guidelines/
  2. Caloric restriction, the traditional Okinawan diet, and healthy aging: the diet of the world’s longest-lived people and its potential impact on morbidity and life span. https://www.ncbi.nlm.nih.gov/pubmed/17986602
  3. Centenarians and diet: what they eat in the Western part of Sicily https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3412743/

Conclusion: The oldest living populations eat primarily plant based diets.


In this presentation we briefly examined four different methods to approach the question: what diet is the healthiest?  We asked this question to better answer the larger question: how do we be healthy? We also listed a few examples and stated a conclusion. 

If our methods are backed with well-conducted studies, then each should hint at the same diet—the healthiest diet. In addition, we should include as many methods and examples as possible in our decision to reduce the possibility that the diet is inaccurate. 

Based on the methods and the examples in this post, we can conclude that the healthiest diet is…

A whole food, organic, plant-based diet, with low sugar and fat

Whole food: The less processed the better (not to be misinterpreted with a raw diet), unrefined carbohydrates 

Organic: Reduce pesticides and other artificial chemicals

Plant-based: Minimize animal products

Low sugar: Minimize simple sugars

Low fat: Avoid excessive oil and fat

Whatever stage of life or circumstance you are in, remember that we should strive for the healthiest diet. Our duty should be to do what is best for our bodies even if it means change. Hold this belief in your mind, and you will realize that change is possible, perhaps even fulfilling.


Let this be our goal so that we may enjoy life to a ripe old age with our friends, our family, our partners, our parents, and everyone around us— no heart disease, no cancer, no chronic disease.


For health stats refer to “health” in issues: https://ponadr.blog/health/