Why Is The Science Of Nutrition Messy & What A Perfect Diet Really Entails?

by | Nov 16, 2018 | Debunking Myths, Healthy Weight, Nutrition, Nutrition Facts | 0 comments

Inside Scoop: A look into the science of nutrition and what to look out for when reading about the latest dietary advice.

This post was submitted by Vania Nikolova, Head of Health research at RunRepeat.com.

In the world that we live in today, every second person is dieting. Everyone is pushing their science-backed weight-loss method.

The problem is that low fat is scientifically sound, keto is also backed by science, paleo as well, plant-paradox, starch solution and other top rated diets too. Which leaves us wondering, how is it possible to have two completely conflicting dietary methods work and yet both be backed by science?

In a way it is and it isn’t. How?

The truth is that the science of nutrition and nutrition research has a lot of limitations. And, people can pretty much just pick and choose the results that they want to back up their claim.

That’s why it’s important to know what to look for when analyzing the latest headlines or doing your due diligence when signing up for the next best diet.





First, it’s important to know that most studies are not done on humans. But on mice and rats.

Usually mice studies serve as a base for a human trial, but sometimes this doesn’t happen. It could be because it’s not ethical, because there’s no funding, or something else.

I don’t have any problem with that and I find rat and mice studies very important and informative.

But when they are cited without even a mention that it’s a rat study, and without even a link, so you can check the source – then I do have a big problem.

Because no matter the similarities in the functioning of mice and men, there are also fundamental differences. Our brains are more complex and our emotions have a huge impact on the results of all interventions.

So, if you’re basing life decisions on a rat study, you’re entitled to know.



Finding volunteers for scientific studies is not the easiest thing in the world. Sometimes studies on diets are conducted with 60, 80, 100 or 200 participants.

This might not sound like too few to you. And if you have some statistical knowledge you might be thinking that the cut off is 30 subjects for a significant result.

But if you control for age, sex, activity level, dieting history and so on, your sample quickly becomes too small. That’s why in a lot of studies of this size, the scientists are not controlling for these variables. And if they are – the results become unreliable.


If you take research from the 80s, most of the subjects are male and ages 20-50. This is not very representative.

Even though this has gotten much better, there is still a lot of research conducted on just Caucasian subjects, only on college students, only on people from a distinct socio-economic class and so on.

So, even if the study was conducted properly, it might not apply to you.



A lot of the studies fail to control for dieting history and eating disorder history of the participants. And this is important.

Most of the subjects signing up for these studies may have had a few failed attempts in losing weight in their past. It’s important to have information for the weigh-cycling that the subjects have gone through the years. But this makes the research much more complicated, so it’s rarely done.



Most dieting studies are very short term – between 6 weeks and 6 months. There are some longitudinal studies that are conducted over 7, 8 or more years, but they are few.

I hope you’ll agree that the results from a six-month intervention are unlikely to last a lifetime.

Usually the 6-month mark is when biology starts to win over the enthusiasm and you start to slowly regain weight, despite the effort. So, this is why I take the results from short-term studies with a grain of salt.



People don’t like change. But when we decide to change, we usually change more than one thing. For a scientific experiment to be successful and to be able to assess the effect of one intervention, this intervention should be conducted with “all else being equal”.

But this is almost impossible for humans. If the study is more controlling, then the people are moved to a facility where their activity and food is measured – but this involves a change in the surrounding environment, which can also have a huge effect on the results.

If the subjects are less-closely monitored, they might start to sleep more, do more exercise or house work, meditate, spend more time with their kids or in nature. They might renew old relationships. All these interventions play a role in your wellbeing.

So, when you’re not controlling for these possibilities, you don’t know the whole story behind the results. And what exactly was the reason for them.


Placebo effects exist in every intervention. Your feelings and predisposition have huge implications on the results. And that’s why in medicine they try to exclude the placebo effects from treatment, because they are different in different people.

But with a diet this is impossible. First you can’t do a double-blind placebo-controlled study, because people know all too well if they are on a diet or not.

Also, the subject’s predisposition to the trial and the predispositions of the scientists themselves to the trial and to the subjects will have an influence. And these effects are hard to exclude, even with clever statistics. Especially when the trial is short, because placebo effects wean with time.



When the trial just excludes the subjects that haven’t completed it, we’re not getting the full picture. It’s important to know how many people found the intervention intolerable and why. What were the reasons for them to leave? What were the side effects they were experiencing?



You never hear of what doesn’t work. We’re only bombarded with information about solutions, not about problems.

Usually if the goal of the trial is not accomplished, if it doesn’t prove what it’s supposed to prove, it doesn’t get published.

So, this robs us from evidence that some interventions are ineffective in some cases. And this skews our views of reality.



Scientific trials are expensive. And finding funding for research is far from easy. So, a lot of trials about food and diet are sponsored by companies with a vested interest.

I am not saying that this is always the case, but these studies usually side with the interests of the funding party.

This is not because scientists are corrupt. When you know what the results should be, it’s hard not to be influenced in your methods and conclusions.

Also, if the reports don’t support the company’s agenda, they usually get buried.


Science is great, but it’s not infallible. And the idea of science is to inform best practices and to make guidelines, which are best for most people.

There isn’t anything in the world that is best for everyone.

I like the example of the car seat in this case. When cars were first coming to market, researchers compiled information, so the seats were adjusted for the average human. And they fit absolutely no one.

No one is the average human in everything – height, weight, blood pressure, length of limbs and so on. The average human doesn’t exist – it’s just an abstraction.

So, what car manufacturers needed to do is to make the seats adjustable, so everyone can fit them personally.

And this is what you need to do with your diet – fit it to yourself, and not to what is “best” for everyone. The information from your own body about how you feel after eating something is much more valuable, than what’s written in an academic paper. At least to you.



Until now we’ve seen how studies become flawed in various ways. This is why there are lots of academic papers proving contradictory things.

Cherry picking is the practice that most diet writers and journalists use, to pick just the articles that prove their point, and ignore everything else. And this is done regardless of the quality of the studies they choose. Regardless of the quantity and quality of the contradicting studies and so on.



See how the science of nutrition can get so complicated?

For researchers, it’s impossible to account for every variable. The mind body connection is so complex and multi-faceted, that it’s hard to study, at least at this point in time.

So, you have the responsibility to find what works best for you. If the diet makes you feel bad, you are not bad – the diet is bad for you. So, be brave and trust yourself!

And, if you’re looking for some help make sure to check out the N5Diet, a 5-week ‘non-diet’ health plan that teaches you how to find your healthy when it comes to food and nutrition. It’s the plan that will help you simplify your health and contains over 125 recipes all made with 5 ingredients or less, a DIY Total Body Fitness plan, tips on grocery shopping, managing cravings and stress and meal prepping easy and delicious meals for you and your family.


Vania Nikolova

Vania Nikolova is the Head of Health research at RunRepeat.com. She spent a lot of years on the dieting treadmill and developed a severe eating disorder. Now she’s recovering and she’s trying to bring more awareness to the subject through her writing.


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