11 min read

What's the Best Human Diet?

boyfriend bento 7-25-07This post was prompted by a debate that I often find myself having with health enthusiasts and even others in the same profession (hey I thought we were on the same side?).

If you disagree with me I’d actually really love to hear from you and understand why, so please leave a comment.

I’ll start by being perfectly upfront and honest:


The best diet doesn’t exist. Click to Tweet

And clinging to an extreme position that there definitely is a best diet, is probably blinding you from the truth.

The nutrition community has never been more divided on the subject of nutrition, but I think many people have over-looked, and continually ignore the grey area between low-fat and low-carb eating; The space that exists between Vegan and Paleo.

The first truth is that most ‘diets’ have more in common than they are dissimilar from one another.

If we want to answer the question, “what is the best human diet.”

We also have to ask, “what if the best human diet doesn’t exist?”

It seems to me that the majority of modern day research analyzing everything from Vegan diets to the Atkins Diet, Paleo Diet, Ornish Diet, and everything in between has been incapable of yielding any significant findings.

What I typically see are some slight differences here or there depending on the health markers a study uses and what risk factors they look at, but generally nothing abruptly statistically different and definitely nothing that would make me state that unequivocally a Vegan diet or a Paleo diet is the healthiest diet out there.

Definitely nothing that anybody could definitively state as fact anyway.

There are some good theories floating around, but even then it’s hard to take them at face value.

Considering nearly every kind of diet has it’s benefits and it’s potential downfalls.

Though that doesn’t prevent certain types of dieters from voicing their often strong opinions to me that are quite to the contrary of what the research seems to reveal.

That their diet is the scientifically proven, best, healthiest diet, and will make your feces smell like rich mahogany and roses.

I get it, you’re passionate about how you eat, but scientifically speaking you cannot tell me that a Vegan diet was proven to be the healthiest human diet any more than a Paleo diet has been, there is currently no grounds to say that a high fat diet is better than a low fat diet either.

With all the existing contention, how can anyone make any formal factual conclusion?

I get it, Nathan Pritikin and Colin T Campbell wrote books on Veganism that drew up some good theories based on what they knew at the time.

I know that Loren Cordain has a good theory on the relevance of eating like our Paleo ancestors too, based on what he knew at the time of writing too.

However, human beings also like to be consistent, so once we’ve outlined a theory, we tend to push our theories really hard down others throats, to a point where, the follower or believers of that diet, suddenly come to believe it as a scientifically proven fact.

Maybe even me…so please question what I write and come to your own conclusions.

Every year there are a dozen studies that come out showing or supporting one theory or another, but a study that draws a correlation between meat consumption and cancer rates, does not mean that this is fact — cough…China Study…cough...

Nor does general public opinion qualify as substantial evidence — as many people have liked to argue with me, if you ask anybody, they’ll tell you that a Vegan or a Vegetarian diet is the healthiest; ya only if you don’t talk to a ketogenic or paleo eater maybe…

If you’re using public opinion, geographical surveys, longitudinal studies or other forms of correlational data to form a definitive opinion, I’d encourage you to read a book on research methods (here is less dense text on the subject), or maybe just start by reading this.

If you blindly follow someone because they make a good argument, seem like they know what they are talking about or have Dr. in front of their name, I’d encourage you to dig deeper.

The nutrition requirements of your typical M.D.?


They are not required to take any nutrition courses in becoming a medical doctor and are generally not responsible for preventative health care either.

Then hopefully start gauging your opinion (which is still very different from fact) based on the highest quality types of research information that is available (Research Reviews/Meta-Analysis and Clinically Controlled Trials).

Many people use erroneous arguments because they ‘believe’ a diet to be the healthiest, as opposed to what the science actually says.

Truthfully we all gauge our perception of various things through a mix of research, personal opinion, personal experience and other influential factors.

However, this should never be confused with a diet that has been scientifically proven to be the healthiest.

A Proven Fact:

“To demonstrate the truth or existence of (something) by evidence or argument in a manner that makes that thing  indisputably the case.”

In other words, a fact means that you cannot dispute it, and yet we have many different camps of nutrition professionals, health professionals and researchers giving the general public the perception that they have all the answers and the indisputable scientific evidence to support it.

Dispute is the opposite of fact.

Gravity is a fact. That the sun rises in the east and sets in the west is a fact.

That <insert the name of any popular diet here> is the healthiest diet out there, is not a fact.

The truth is that most typical ‘diets’ are incredibly well crafted theories or opinions, largely based on what we think we know.

The only factual conclusion that I’ve been able to draw in my research is that the typical ‘control diet’ (AKA the typical western diet) consisting of heavily processed, refined and modified ingredients is as everyone agrees is definitely not the healthiest diet.

Beyond that, what makes up the diet (high protein, high fat, low fat, high carb, low carb, paleo, vegan, vegetarian, etc…), doesn’t really seem to matter that much, so long as you meet your nutritional requirements.

There are also certain risks that anybody who falls into a certain ‘camp’ or style of eating (like paleo, vegan, vegetarian) should probably be educated on, so as to optimize the foods they are consuming in a way that meets nutritional requirements.

Every ‘diet’ of this nature has it’s flaws.

The majority of these risks can be minimized or eliminated through proper education and in some cases supplementation.

Furthermore, it has become very apparent to me that labelling nutrition in such a fashion may actually be doing more harm than good psychologically; as the stress of ‘clean eating’ or ‘restrictive dieting‘ can lead to poor health outcomes.

Nutrition is definitely not the only thing that influences health, even if it may be a significant component.

What the Research Actually Says

When you look at higher quality pieces of recent research a very different picture appears to be painted than the one that many people in various nutrition camps might like us to believe.

Let’s go through a few:

#1 – Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Randomized Trial

Seems to show no statistical difference from any of these diets on the amount of weight loss that occurs, nor the health markers relative to heart disease.

Granted that’s only one study, that only looked at weight loss and heart disease, so what else have we got…

Well very recently there have been quite a few high quality meta-analysis’ looking at similar data from a clinical setting (a variety of diets ranging from Vegan, Vegetarian, Zone, Atkins, Paleo and beyond):

#2 – Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes.

On the topic of diabetes, when you compare the various diets they used over 20 different studies comparing various types of diets; The researchers could find no statistical evidence suggesting any of the diets were any more or less effective at changing the health markers outside of the control diet — a typical crappy western diet, which, I’m sure most of us can agree is not a great choice overall.

Lets look at other cardio-metabolic risk factors though…

#3 – Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-anlysis of randomized controlled trials… [Am J Clin Nutr. 2012]

“Compared with an Standard Protein (SP) diet, a High Protein diet produced more favorable changes in weighted mean differences for reductions in body weight (-0.79 kg; 95% CI: -1.50, -0.08 kg), fat mass (FM) (FM; -0.87 kg; 95% CI: -1.26, -0.48 kg), and triglycerides (-0.23 mmol/L; 95% CI: -0.33, -0.12 mmol/L) and mitigation of reductions in fat-free mass (FFM) (FFM; 0.43 kg; 95% CI: 0.09, 0.78 kg) and Resting Energy Expenditure (595.5 kJ/d; 95% CI: 67.0, 1124.1 kJ/d). Changes in fasting plasma glucose, fasting insulin, blood pressure, and total, LDL, and HDL cholesterol were similar across dietary treatments (P ≥ 0.20). Greater satiety with HP was reported in 3 of 5 studies.”

So here we have some slight overall differences but generally speaking no statistical difference relative to health markers on a whole.

In some cases, higher protein, low carb diets induced better physiological changes in certain cardiometabolic risk factors, which in some ways seems to contradict the typical recommendation in the medical community for a low fat/high carb diet.

I’d argue however, that overall the differences are not very significant and the various types of diets appear to have their own slightly unique benefits (or edge) over other diets, so potentially what outcome you want to achieve in your eating may influence what option you choose.

Here’s another Meta Analysis looking at metabolic risk factors.

This time they looked at research as far back as 1966!

#4 Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials… [Am J Epidemiol. 2012]

Once more, the research seems to indicate that there is little to no statistical difference between various types of diets.

However, once more the low carb diet fared slightly better in certain metabolic risk factor predictors like a greater reduction in total cholesterol, and LDL’s, as well as a greater decrease in triglycerides.

I think researchers note this because it is contrary to what they might expect based on what the scientific consensus was on diet in the 70’s, 80’s and 90’s.

However, to me the research also doesn’t statistically suggest that any particular way of eating is significantly better, just they all tend to yield the same or similar result in the end.

#5 Comparison of Effects of Long-Term Low-Fat vs High-Fat Diets on Blood Lipid Level in Overweight or Obese Patient: A Systematic Review and Meta-Analysis

Lets look at more high quality research (4 meta-analysis’ deep now…which I hope qualifies as statistically significant to more scientifically astute readers).

I’d just like to note what the authors of this meta-analysis state:

“The results of our meta-analysis do not allow for an unequivocal recommendation of either low-fat or high-fat diets in the primary prevention of cardiovascular disease.”

Once more, that seems to indicate that any notion that any diet has been scientifically proven to be the best, is currently false, at least based on what we know so far.

#6 Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis

Here’s what this one had to say:

“According to the present meta-analysis of long-term RCTs, high-protein diets exerted neither specific beneficial nor detrimental effects on outcome markers of obesity, cardiovascular disease or glycemic control. Thus, it seems premature to recommend high-protein diets in the management of overweight and obesity.”

That’s just to provide a little balance, as a couple of meta analysis’ above may give certain people the impression that a high-protein diet has the slight edge and I’m not entirely sure it does.

Though I will say that I do think the existing protein recommendations are generally low, I’m not so sure that a ‘high-protein’ diet is without a doubt the answer either and remain a little moderate in my approach.

I typically favour more of a 1.8 grams per kilogram of bodyweight recommendation for athletes and trainees, as opposed to the more common 1 gram per pound of bodyweight, or 2.2 grams per kilogram of bodyweight.

#7 Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults – A Meta-Analysis

Once more the article speaks better than I can:

“Significant weight loss was observed with any low-carbohydrate or low-fat diet. Weight loss differences between individual named diets were small. This supports the practice of recommending any diet that a patient will adhere to in order to lose weight.”



The main point I’m trying to make here is that more and more research papers are unable to show any statistically significant differences between various non-western diets in weight loss, cardio metabolic risk factors, cancer rates, diabetes, etc…

The current scientific consensus seems to be that no such ‘best’ or ‘perfect’ diet exists, despite what you may think.

So rather than continually debating what the ‘best diet in the world is,’ making nutrition more like a religion, and less like a science; Maybe we should divert our attention and start focusing on what really matters in the long run:

  1. Behavior Modification (Habits)
  2. Skill Acquisition (Exercise & Cooking/Nutrition)
  3. Diet Adherence
  4. Meeting Nutritional Requirements
  5. Individualization (based on personal need and objectives)

Diet isn’t, and most likely never will be, a one-size-fits-all strategy.

That’s why I actively promote what I’ve come to call the Agnostic Diet.

I also sometimes like to call it the anti-diet, given how many people approach diet these days.

It’s the notion that everybody needs to go through a process of discovery to determine what approach to eating works for them.

I like to think of it as fitting the diet to the person, rather than attempting to fit a person to a diet.

Diet is really the average sum of food that you consume over a period of time, so you’re always ‘on a diet’ already.

However, if you want to use a popular diet like the Zone Diet, or something like Veganism (because it resonates with you) or Vegetarianism or the Paleo diet as a framework in your process of discovery, so be it, these are generally good places to start and tweak from.

A common theme of most good diet strategies is that the remove heavily refined, heavily processed foods and as I already indicated, that seems to be the only diet we know for sure isn’t the best diet.

I still encourage you to make one change a time so that those changes are more manageable, and stick long-term.

Make a change, see how it goes, learn from it, then make another change, see how it goes, learn from it and keep going until you arrive at a complete or holistic eating strategy that works for you.

Hopefully my resource page on diet gives you some ideas.

Go through that process, and over time form an opinion or make a judgement call, based on what you experience, then roll with that until you see that it doesn’t work and discover what does.

If you want to create physical change, then you need to make changes to diet over time.

Just please don’t tell people that what you determine is the fact of eating for everyone else! That does more harm than good…

Seriously, claiming that a diet is the best diet for health or weight loss is the same as asking people to adhere to a strict diet which can lead to problems, like nutrient deficiency (without proper education in various kinds of eating) or psychological issues like cognitive dietary restraint.

Asking someone to follow a diet that they’d have a very hard time following in the first place, might do the opposite of what you intend.

You end up with a population that was fat-phobic and is now carb-phobic, instead of a population with a variety of methods that works for each of them and all or most of them at a healthy weight.

Instead, I’d ask that you pay it forward and help other people go through their own process, productive feedback from others can cut the time it takes to find an approach to eating, that fits a person’s personal preferences and suits their needs.

This has a significantly better chance of helping everyone achieve long-term success — regardless of the style of eating you or others may end up on.

The only thing that seems clear is that a processed diet from an industrialized food system is theoretically a very significant issue in terms of health and weight.

Otherwise, it’s really up to the individual. Can’t we all get along?

If you had the energy to read all of that and still have more, please a leave a comment.