What about processed food is so bad?
You probably know that fresh food is better than processed food. It’s better to have some fresh fish, vegetables, and rice than to have a frozen pizza. It’s better to have oatmeal and fresh strawberries than a bowl of sugary cereal.
Examples of highly processed foods are sugary drinks, chips, frozen meals, most breakfast cereals, pre-packaged pastries, deli meat, sausages, hot dogs, things like that. People who eat a lot of processed foods may have an increased risk of developing obesity, diabetes, cardiovascular diseases, mental health issues, and some types of cancers.
That sounds bad. So what is it about processed food that makes it so bad? There is no shortage of potential reasons. Let’s take a look at some of them.
First, a lot of processed food has high levels of fat, sugar, and salt. Consuming too much fat, sugar, and salt can lead to bad health outcomes. But that cannot be the whole reason why processed foods are bad. After all, almonds have a lot of fat and an orange has a lot of sugar. I doubt many people die early from eating too many oranges.
Ah, you might be saying, but it’s difficult to eat too many oranges: you’ll feel full before you overindulge. That brings us to the next reason why processed foods might be bad for you. It’s easy to eat too much of them.
Processed foods tend to be calorie dense. Whatever they have—good or bad—there’s a lot of it per bite. Here, it’s helpful to look at the nutrition per gram, or per hundred grams. An orange has 47 calories per hundred grams; a sugary breakfast cereal might have 200 to 300 calories per hundred grams.
In other words, you can eat the same amount of food, but get many more calories—and much more sugar and fat—from processed foods than from natural foods.
The weight of food in your stomach helps tell your body that you’re full, to stop eating. But that’s not everything; the composition of your foods also affects your satiety. Many processed foods contain combinations of ingredients that can interfere with your body’s natural sense of fullness, or satiety.
For example, the combination of fat and sugar is uncommon in natural foods. An avocado is fatty; a banana is sugary. But few things in nature are both. Our satiety mechanisms are more responsive to foods that are high in either fat or sugar, but may be less effective for foods containing high levels of both. And, you guessed it, many processed foods have that combination, making it all too easy to eat too much.
What else is wrong with processed food? Look to the ingredient list. Some processed foods contain chemicals and ingredients that don’t occur in nature and are not in any household kitchen. Preservatives, emulsifiers, artificial colors, sweeteners, and other ingredients are tested for safety in regulated quantities. However, the long-term effects of consistent high intake of these ingredients over many decades are still being studied.
What about the processing itself? Some foods may start with healthy ingredients, but the industrial processes may strip out the naturally-occurring micronutrients in those foods. Take a bowl of Cheerios. Cheerios is a relatively innocent player in the cereal aisle. There isn’t much sugar. The ingredient list is mercifully short. The number one ingredient is whole grain oats. But before those whole grain oats get into your bowl, they go through an intense industrial process called extrusion.
In extrusion, the natural ingredients are subjected to high pressure and high heat and then forced through a tiny opening to form the final shape. In the process, a lot of micronutrients that occur naturally in oats are lost.
So there are a lot of things that might be bad for you about processed foods. But it’s hard to know which factor—or which combination of factors—is the one that causes people to suffer bad health.
There’s another problem, too. Processed food isn’t the only thing that leads to disease. Smoking, stress, activity levels, genetics, income, education, and many other things affect a person’s health. So any scientific study that looks at the population as a whole has to contend with the fact that there are many other variables at play besides food.
And that makes it harder to study what, exactly, is it about processed food that’s so bad. It could be that that some processed food, or some production methods, or some ingredients, are relatively innocent, while others are more harmful.
The good news is that this is where scientific studies are starting to make progress. One study from 2024 found slightly higher mortality from study participants that ate highly processed foods, and the study found processed meats were among the highest contributors to bad health outcomes. But the study also found that a person’s overall diet quality was more important than whether they consumed processed food as part of their diet.
Another study analyzed specific groups of foods, and found that not all processed food is equally harmful. Whole grain bread is a processed food, but was not associated with poorer health in that study.
Randomized controlled trials are the best way to measure the effects of single variables, but these can be expensive and time-consuming. They are also not practical for long-term studies, since study participants don’t report accurately or they struggle to stick to the diet they’re assigned.
But you can still learn a lot from short-term studies. In one, participants checked into a “diet hotel” and were given either processed or non-processed food. They were allowed to eat as much as they wanted. After two weeks on one diet, they switched to the other. People on the processed food diet ate 500 calories more per day and gained a kilogram of weight over two weeks.
More detailed studies like this one can modify the test diets to see which types of ingredients or which processing techniques lead to the worst outcomes in the short run. With time, that could lead to more informed decision-making and more effective labeling and regulation.
Jeff’s take
I heard someone give this great rule of thumb. If you can picture, in your mind, the food traveling from where it was grown to how it got on your plate, then it’s probably not that bad in the long run.
You can imagine a strawberry growing in a field, a machine picking it, it goes in a carton, and you buy it. Sure, there’s refrigeration and washing, but it’s easy to imagine.
How does a package of Oreos get made? I couldn’t even tell you. I wouldn’t know where the ingredients grow. I wouldn’t know how the white filling gets made—I don’t even know what it’s made of. Sugar, clearly, but what else? What is it? And how much of that cookie part is chocolate and how much is just brown food coloring?
So think about that. At your next meal, stare at your plate and try to imagine what happened to your food from the time it occurred in nature to the time it got to your house. If you struggle to imagine it, you might be eating highly processed food!
I’m not a doctor, but I say once in a while is okay. I still eat Oreos: I’ll admit it!
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