Why There Is No “Best” Diet

There really isn’t a one-size-fits-all diet that’s optimal for everyone

For decades, professionals in health care and non-professionals have argued about which diet is best for health and weight control – and the argument gets heated as the low carbers duke it out with the low-fat proponents and those who advocate a mostly plant-based diet. And the battle rages on.

Is a plant-based diet the ultimate eating plan for health and fitness or should you restrict carbs if you’re trying to get to healthy body weight? Are calories in and calories expended what’s most important or is it the quality of what you eat that matters most?

In reality, all of these opinions may be right AND wrong. Ultimately, the best diet for weight loss and health comes down to the individual. What works for one person may be unsustainable or even harmful for another. Just as we each have varying food preferences, the best foods for health and wellness may differ from individual to individual.

Plus, we’re all a bit different from a physiological and psychological standpoint and also vary genetically. Inside each cell in your body are sequences of DNA that encode for the RNA, which, in turn, codes for the proteins that make up hormones and other factors that influence health and body weight. Person A may have a DNA sequence that’s different from person B. Therefore, their hormonal milieu is different as well.

No Two Gut Microbiomes Are Alike

Then, there’s the issue of gut bacteria, the residents that make up the gut microbiome. We actually have more bacteria in our gut than cells in our body! We have a veritable forest of bacteria lining our intestines. Researchers liken the microbiome to a unique “fingerprint” that differs from individual to individual – and research shows our microbiome composition impacts factors like nutrient and micronutrient absorption and appetite. These industrious and ubiquitous little bacteria may also influence body weight.

What we eat affects hormones and the bacteria that live in our gut, our microbiome, and we know that these factors differ from individual to individual. What works for a person with microbiome A may not be optimal for a person with microbiome B. No wonder, precision nutrition, the science of designing a diet that works with an individual’s genetics, is still in its infancy. But, it’s also an approach to nutrition that’s growing.  People need solutions that take into account their own unique genetics and microbiome.

Here’s an example. People differ in terms of their insulin sensitivity, hormonal makeup, brain biochemistry, and microbiome. Someone with poor insulin sensitivity might best be served by a lower carb diet and the elimination of all processed carbs, whereas an individual with good insulin sensitivity might derive no real benefit from cutting back on unprocessed carbs. That’s why the “perfect” diet for the population as a whole may not exist. This doesn’t even take into account food sensitivities and allergies. Yet, people still search for and argue about the ideal diet.

In the future, thanks to precision nutrition, health care practitioners will soon be able to tailor an individual’s diet to better match their unique characteristics. What exactly is precision nutrition? It’s the science of managing health risks and chronic disease using dietary recommendations based on an individual’s genetics and metabolic profile.

Diet Habits That Benefit Most People

Even though we can’t say that one specific diet meets the needs of everyone, research does show that certain eating habits are beneficial for most people. For example, it’s unlikely that anyone derives benefit from eating a diet of refined carbohydrates and sugar. Some insulin sensitive people may tolerate such a diet better than others, but you could hardly call a plate of highly processed foods healthy.  Even people who seem to do okay on a diet of fast food may have health repercussions from eating that diet down the line.

So, cutting back on highly-processed foods, added sugar, and starchy foods that have limited nutritional value has few health risks and lots of potential benefits. Two eating styles supported by research are the Mediterranean diet and the DASH diet. Both eating plans emphasize plant-based options, lots of fresh fruits and vegetables, whole grains, legumes, healthy fats from sources like olive oil, nuts, seeds, and lean protein from sources like fish and modest amounts of chicken.

The DASH and Mediterranean diets de-emphasize highly processed foods, sugar, and red meat. The main difference between the two is the DASH diet includes more low-fat dairy foods than the Mediterranean diet.

Both diets appear to have health benefits. For example, studies show that the Mediterranean diet is linked to lower mortality in both healthy people and people with heart disease. In fact, the DASH diet was originally promoted as a diet to lower the risk of hypertension and for people who already have high blood pressure. Plus, both diets are varied and offer an abundance of whole food options.

The Power of Fermented Foods

Another dietary component that most people don’t get enough of is fermented foods. Fermented foods come in a variety of forms from fermented dairy, like yogurt and kefir, to fermented veggies, like sauerkraut. Both offer an abundance of gut-friendly probiotic bacteria. Getting some of these foods each day helps support a healthy gut microbiome. Plus, fermented vegetables are rich in prebiotics, a type of fiber that fosters the growth of probiotic, gut bacteria.

The Bottom Line

When you hear someone say they know the best diet, ask them for who? Because there really isn’t a one-size-fits-all diet that’s optimal for everyone. However, most people can benefit from a Mediterranean or DASH diet. Even better, don’t think in terms of “diet,” but simply choose more nutrient-dense, whole foods as opposed to highly processed ones.

Also, be aware of possible food intolerances and food allergies. Food allergies are mediated by the immune system, whereas food intolerances simply mean your body doesn’t respond well to those foods, although you aren’t truly allergic to them.

If you suspect you have a food intolerance, keep a food journal for a few weeks and see if your body doesn’t tolerate some foods as well as others. If you find such foods, eliminate them from your diet. Food allergy testing is available but isn’t particularly accurate. So, you might have to experiment a bit with what you eat and see how your body responds. That way you can establish an eating style that works for you.



Lancet Diabetes Endocrinol. 2018 May;6(5):416-426. doi: 10.1016/S2213-8587(18)30037-8.
J Transl Med. 2016; 14: 91.
European Journal of Preventive Cardiology. Vol 23, Issue 4, 2016.


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