Processed Food vs Real Food: Why Nutrition Science is So Confusing (and what to do about it)

by | Sep 1, 2015
Photo by Daniel Gois

Photo by Daniel Gois

Recently a reader asked me a simple question that I’m surprised I don’t hear more often, “Why are processed foods so bad?”

She had been having a nutrition debate with her boyfriend. She reads Summer Tomato regularly, but was having trouble describing the health difference between the Real Food I recommend daily and the processed foods I warn against. What exactly is the evidence?

Great question.

The answer in some ways is just as simple: we don’t know. Unfortunately that isn’t very satisfying intellectually, and our attempts to create theories around the observational fact that obesity and most chronic diseases only appeared after the introduction of processed foods has opened the door to a world of speculation and confusion.

There is no doubt that processed foods are unhealthy. The so-called Diseases of Civilization including heart disease, hypertension, tooth decay, diabetes and some cancers were virtually non-existent before processed foods (usually flour and sugar) were introduced.

We know this because these foods didn’t magically appear in all places at once, but gradually became available to different populations. The longer cultures were shielded from these ingredients, the longer they remained healthy. There is a fascinating account of this phenomenon in Weston Price’s book Nutrition and Physical Degeneration, but he is not the only one who made these kinds of observations.

Still we do not know why processed foods have this effect. There are many hypotheses about what the problem is. Some have blamed “carbs,” others have blamed fats. These days it is fashionable to point fingers at particular kinds of sugars like glucose, fructose or sucrose. People have argued that excess blood glucose and insulin are the issue, while others point to the metabolism of fructose in the liver.

Some say it isn’t the carbs at all, but the gluten protein in wheat that is to blame. If you prefer to pick on animals, there are plenty of people who think animal proteins are the true culprits.

It has also been suggested that the processing method itself is what renders foods unhealthy. Processing food typically removes or destroys nutrients and fiber, which are present in the whole foods that remain healthy. It is possible that these nutrients are required for health, though adding them back in the form of supplements does not seem to solve the problem.

Added preservatives, chemicals and other synthetic substances present in processed foods may also play a role in their unhealthfulness. Or perhaps it is our own biology that has not adapted to quickly digesting foods, or foods that have been processed in a particular way. Trans fats, for instance, are synthesized when oils are hydrogenated by a specific method, and these are almost never found in nature.

Some folks even go so far as to blame pH levels and blood types for our ailing health, though these claims are rarely made by real scientists.

You can find circumstantial evidence to support all these claims, and people do. It’s relatively easy to develop an opinion about nutrition and find a camp that is adamant about its validity. They’ll show you all sorts of data about things that happen in test tubes, in large uncontrolled human populations, or in mice, and insist that you’re a fool for not believing them.

There’s even a good chance they’ll lift their shirt and show you their six-pack as additional evidence of their correctness. And who can argue with abs? I know I can’t.

It’s confusing because a comprehensive scientific explanation of our observation doesn’t yet exist, and probably won’t for a long time. As I explain in chapter 4 of Foodist, nutrition science is very complex and still in its infancy:

“Humans are omnivores, which means we are adapted to eat plants, fungi, and animals. The nutrients in the plant foods we consume depend on the genetics of the individual species, the quality of the soil they are grown in, and the weather conditions during that time. For animal foods, nutrient levels are dependent on what the animals eat throughout their lives and are also affected by their stress and hormone levels. Any toxins or environmental pollutants that the animals and plants are subjected to have the power to impact human health as well.

Nutrient levels of raw foods change depending on the amount of time between harvest and consumption (sometimes going up, sometimes going down), and your cooking method may destroy some nutrients while making others more available. Individual nutrients within a food do not work in isolation, but interact with each other to affect bioavailability (i.e., how our bodies are able to use them). Similarly, the nutrients in one food can interact with the nutrients from another food if they are consumed in combination. 

Your metabolism starts responding simply to the smell of food.* How quickly you eat and how much you chew also impact how your body handles it. Your own genetic makeup as well as your fitness level dictate how you respond to different levels and combinations of nutrients, and your digestive tract contains trillions** of microorganisms that affect what you can and cannot absorb. Individuals vary greatly in their sensitivity to different micro and macro nutrients, and all of us have different personal health and fitness goals.

* Amazingly, smell has been shown to significantly impact longevity in some species via the insulin-signaling pathway.

**Not exaggerating.”

We really have little idea how all these factors work together to impact the health of an individual, and it will likely be several decades before we do. Still the debates will rage over the various theories about what constitutes the healthiest diet, and people will continue to miss the point entirely.

At the end of the day it really doesn’t matter what the reasons are, since we already know what to do. Simply eliminating or drastically reducing the amount of processed foods you eat vastly improves your health. The scientific mechanisms that explain this are certainly interesting on an intellectual level, but you don’t need to understand them in order to eat well.

This is why my work focuses almost exclusively on behavioral change and psychology. Understanding how to actually eat well (instead of just telling yourself you should and hoping for the best) is far more important than theories about why some foods are healthy and others aren’t.

In fact, if you don’t have a background in science focusing on nutrition theories is likely to be counterproductive, since there is a good chance they will lead you down a path of extreme diet rules, such as avoiding all grains and legumes. Yes it is possible to be healthy without including everything, but it is more work. And more work tends to derail healthy eating.

A more practical approach is to tinker with your behavior until you find a set of habits that make it easy for Real Food to become the majority of what you eat. You know it is working if your new behaviors are easy––essentially automatic––and don’t feel like hard work.

You should also be able to measure the benefits, like being a healthy weight, having lots of energy, normal blood lipids, etc. Maybe you will need to eat fewer grains or more protein, but science can’t tell you that. Only trying it for yourself and seeing how it affects you can. Author Nassim Taleb might call this approach more antifragile.

Nutrition is complicated, but eating is not. Spend your energy discovering what works for you and try not to get too caught up in the science.

Has letting go of nutrition theories helped you get healthier? Let us know in the comments.

Originally published July 30, 2014.

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34 Responses to “Processed Food vs Real Food: Why Nutrition Science is So Confusing (and what to do about it)”

  1. Sean says:

    There’s a term that was coined I think with the environmental movement called the “precautionary principle”. In its most simplistic form it means to take action based on likely risk even in the absence of scientific consensus or extensive research.

    It seems to apply well here to this analysis of what’s so bad about processed food. Does it really matter exactly what might be so bad about it? I wouldn’t holdout for a scientific consensus before taking action to shift ones diet towards more real/whole foods.

  2. Monica says:

    If it was just easy to get this message across to people.
    I’m striving to become a registered dietitian and among all the nutrition literature I read, there is just so much controversy.
    I have to look it up who coined this phrase, but it’s one that really resonates with me and I presume you too : “the active ingredient in broccoli, is broccoli”.
    But that doesn’t satisfy the masses, unfortunately and reductionist science has ruled the marketing strategies to benefit the snack-foods industry.
    I’m so glad you posted this, especially the note on using a chiseled abdominal region as evidence of health.
    As a future dietitian I hope to carve myself a career that is more in line with the food movement and emphasize preventive nutrition therapy as opposed to reactive nutrition therapy i.e treating diseases. That’s why I volunteer at the farmers markets and intern at a cooking school instead of working for a hospital (which is the traditional route to dietetics).
    Thank you for posting this!

  3. amy says:

    Thank you, Darya, that was fast! I really appreciate your work, and I hope this will help me make my case with said boyfriend.

  4. Alex says:

    Are there “healthy processed foods”?

    For example, garlic granules, vinegar, turmeric, cayenne pepper, yogurt, etc.

    All of these foods are processed yet very healthy (or at least in my case).

    What’s your opinion Darya?

    • Dave says:

      they are processed foods but minimally processed for the most part.
      garlic and tumeric are just (or should be just) dried and powdered.
      vinegar and yogurt are ferments. both can be naturally done and done so ‘by accident’. leave some wild grapes in a bowl on the counter covered with cheesecloth and 2 to 3 weeks later you’ll have wine vinegar. loaded with probiotics.
      the processing of the foods you mentioned (plain yogurt only!) requires just leaving something alone to let it dry or ferment. nothing added, nothing removed. (some people add a starter to their ferments but it’s not always required)

    • Darya Rose says:

      I agree with Dave. The foods you mention are minimally processed through natural methods that existed well before the industrially processed foods I’m referring to here. So yes, they are healthy. Especially anything that has been fermented.

  5. rumba says:

    Some ideas! Most processed food manufacturers try to prevent lipid peroxidation, but protein and cholesterol oxidation were not considered such a problem in the past. All of the recent scientific literature,however,suggests oxysterols are highly atherogenic. Not so sure about protein oxidation, but protein intake from meat is positively correlated with mortality.

    Oxidation is rarely a problem in raw meat and dairy. Storage and heating are the main causes of oxidation.

  6. Darya, great post – good common sense! I can’t be bothered to worry about all the details of every new diet about which a new book comes out every week. Common sense tells me that whole foods are good and that there is nothing convenient about “convenience foods” that eventually cause very inconvenient health consequences.

  7. “Why are processed foods so bad?”. That’s a question I have been asking myself too, so thanks for a very well-written and interesting answer!

    I have heard that it was the introduction of sugar that was the starting point for the cardiovascular problems we see today. But you are saying processed foods are to blame?

    Anyhow, I just found your site. Will check it out!

  8. Dave says:

    it’s hard to describe to people what it means when you tell them to “just eat healthy”.
    but i think there are a couple of ‘rules’ to try to follow when eating healthy.
    try to eat things that don’t have bar codes on them. try to avoid stickers too.
    try not to eat what your grandmother wouldn’t recognize. she may recognize a loaf of bread but she probably won’t recognize the ingredients. (from michael pollan)

  9. GCC says:

    Those interested in this topic might want to check out an article by Tamar Haspel on the Washington Post website entitled “Processed foods: The problem probably isn’t what’s in them. It’s what’s not in them.” It presents one view of the problem with processed foods, with some interesting thoughts on the relative risks of food additives.

    Haspel actually has a whole series of articles on the Washington Post website that talk about the intersection of food and science and I’ve found them to be really balanced and interesting. They’re a great complement to the posts here at Summer Tomato. You can read them here if you’re interested:

    Unearthed – The Washington Post

  10. Tarek says:

    Autre fois on nous mettait en garde contre le tabac,maintenant tout est cancérigène,la viande les pattes le yaourt,on ne comprend rien du tout.

  11. Elizabeth King says:

    Hello Darya, I have read your book “Foodist” & found it very refreshing. Every where you go on the web or in magazines etc. someone is saying this is bad for you & that is bad as well. There is a plethora of different opinions & diets to choose from. It is difficult to know what to believe. Anyway I find your site & book to be down to earth & practical & it was & is a breath of fresh air to read. Thanks for that & for all your good information as in your answer above.

  12. Dee says:

    Very well written, I love it!

    I used to think that nothing is wrong with processed food because people won’t make poison or toxins for us to eat…. Two annoying words these days – paleo and gluten…I feel relieved not trying hard to avoid bread and lentils.

    Be grateful for the food industry and processed food – America has a huge population 300+ million think of the ‘food chaos’ (India, China) that would’ve been without this massive industry

    I just eat a wide variety of high quality foods made from the world of living things. 5 food groups – plant, animals, fungi, algae, bacteria. I make my menus/ grocery list based on the subgroups of these. I don’t need to be part of the food system or other people’s food ideology

  13. There is this prominent opinion about preserved food and we all know that. I am personally fizzy about the containers that comes with a limited expiry. I cannot truth a plastic box! And then we also not sure about their quality. This is my basic concern :/

  14. Don V. says:

    Darya, I’m no expert on anything, but I know good common sense coupled with education and intelligenc and you have it! Thanks

  15. Roberta Saum says:

    I love this Darya!

    I’ve followed the Weston Price and Nourishing Traditions style of eating for a long time now. I veered off track with some processed foods last year and found I actually got some bad physical reactions that went away once I stopped and got back on track. It was actually helpful to get immediate biofeedback to remind me why mostly one ingredient foods as fresh from the farm as possible is what makes us feel best. In the correct balance and portion for our own body of course. I think it’s hard for people when they don’t seem to feel difference so it doesn’t seem like it matters.

    I was really happy to see you mentioned Taleb’s book, my husband has been raving about “Fooled by Randomness” and Antifragile and really wants me to read them, along with the other books by Taleb. He especially wanted me to read Antifragile because he’s seen my approach to my diet, what I eat and when I don’t eat, etc. I shall have to make this reading a higher priority!

    Thank you for this post!


  16. This is very interesting because I’ve always tried so hard to listen to the science and constantly change what I eat according. I’ve always been gluten free which helps my digestive system a lot, but now I feel like I don’t have to justify it to my peers in a scientific way. Thanks a lot!

  17. Dorothy says:

    Great post! Thanks for being upfront about the ambiguity that persists in the research and for respecting your readership enough to know that they can handle the messy truth. And thanks for the v practical takeaways, too.

  18. Dina says:

    I have always thought that our bodies are supposed to be doing the processing, starting with chewing and following along with the rest of the digestive process – not food manufacturing plants. Eating processed foods means that the digestive process has been started before we even put the food in our mouths, so we are losing out on the nutritional and metabolic benefits of the early stages.

  19. Ana Julia says:

    Hii Darya.
    First I wanna to thabk you for your great job. I really love how you write and inspire people. That’s what the world needs.

    No more blah blah. It’s real information about what really matters.

    I’m from Brasil and I’m trying to be healthier and inspire others to be too

  20. Craig says:

    My journey towards the Foodist non theoretical way and away from the so called healthy processing after steady but faltering progress began 45# ago. I lost weight and improved cholesterol. But everytime i hit a wall i searched amazon. A good book somewhat paleo is called refuse to regain. The author was right in my case to some degree. I reduced legumes and increased meat. But i still hit a wall. Rose’s Foodist strategies and habits have really kicked in. Some legumes and grains have been key in managing appetite ie outrageous binge craving. Im not a walking eating disorder but close. Foodist got my weight down enough and off diabetes and hypertension meds. Still need more energy though and hdl is a bit low yet. Still losing. Now i want to be a wellness coach based on foodist guidelines and spirituality. Thank you!

  21. Justine says:

    This was a refreshing read. So many food/health blogs I’ve found subscribe fervently to one camp, science and ambiguity be damned, so it’s nice to see a balanced take on the subject. Thanks.

  22. Paul Block says:

    I think processed food is meant to sell, period. And they take advantage of our addictions for flour, butter, salt & sugar. And,as you say, they’re filled with chemicals and colors and ‘natural” favors. I believe it’s all about behavior and habit, as you do, and the processors know that, and feed, the habit.

    • Albert says:

      Although we enjoy the flavors of sugar and other added chemicals, our body and digestive system did not adapt to processed food, which is indeed meant to make money and save money.

      You simply cannot sell healthy, natural food for the same price. The price for growing healthy food is much higher. So, unfortunately, it all goes back to… money…

      All we can do is to be aware of this and act accordingly.

      PS Antifragile is a very good book!

  23. Jo-Anne says:

    Me, what do I think? I believe when we outsourced the growing and harvesting; cooking and preserving; servings and portions; etc. to the factory is when the rot set in. Company profits override the health and wellness of the nations and it’s peoples, and personal profits override the health and wellness the family and it’s members.

    I am not saying I want to go back to the ‘good old days’, as my dodgy herb garden can attest, take off my shoes and put on the apron, but the corporate model for healthy industrialised food fit for good health and wellness can include duty of care along with profit…they are not mutually exclusive.

    Supply and demand…stop the demand for factory food, and increase the demand for real food and watch the manufacturers jump through hoops to please us. Yep, it will feel as if we will be experiencing a famine during an adjustment period but mankind has already survived many natural famines and I am sure we can survive another.

  24. someone random says:

    ummm… I don’t get it

  25. Geoff says:

    Hi Darya,

    This is an excellent article. I really like how you point out the limitations of current science without creating skepticism of science as a whole.

    The trouble with becoming a scientist is learning how much science doesn’t know (and how much the public *thinks science knows!)

    I love the honesty that you present the information with in this article. Such a breath of fresh air in the health/fitness genre.

    Although it does make me wonder, do you have some of your own opinions about different diets and whether some of them really are better than others. If so could share a couple of thoughts?

    • Darya Rose says:

      I wrote a whole book on this topic, but the short answer is anything you consider a diet (I.e. Restriction) is a bad strategy for psychological reasons. That said, I still prefer plans based on real foods as opposed to processed foods.

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