why processed food kills your waistline and mood, and how you can save both

We already know that highly processed foods are bad for you. But several new studies show that it's even worse for you than we thought, damaging both your waistline and mood.

Over the past century, humanity has been doing great things when it comes to giving us more years on Earth. After we mastered sanitation, antibiotics, and vaccination, our life expectancy exploded. It should be noted that lifespan and life expectancy are two different things, but point is that we’re much more likely to survive childhood without some sort of fever killing us, and infections that would ordinarily kill or weaken us can now be treated with antibiotics. As a result, more people than ever are making it to old age and are starting to worry less about lifespan, and more about “health span.” And a major part of a good quality of life is keeping one’s weight in check.

The simple truth is that if we want to make it to the biological limit of 120 years or so, we have to make good choices. Unfortunately, a lot of us haven’t been doing that, and that’s especially true when it comes to food we tend to shove down our gullets after a long, rough day of work. Study after study found very strong correlations between the highly processed food — food with added preservatives, salts, and sugars, if not flash frozen and pre-cooked — that often ends up on our plates expands waistlines, raises risks of some cancers, and can even trigger depression. This holds true even as we’re processing less and turning to fresher, ready-to-eat supermarket fare more.

how to really study what people eat

But why does adding any measure of convenience to our diet seem to backfire on us so badly? Is there something special about processed food that makes it so insidious? Usually, nutritional studies rely on reviewing self-reported records and logs from tens of thousands of people, then trying to correct for predictable lies and omissions, and well known variations in their behaviors with statistical formulas. But that just wasn’t quite enough for a one team of dietitians who needed the honest details, and not have to strategically fudge numbers. They wanted causality, not more correlations, and the only way to do what was to have complete control over what their subjects ate.

For a month, 20 paid test subjects were kept in total isolation, eating only what they were given with no exceptions or room for improvisation in their meals. The only twist is that they could eat until they felt full instead of a precise serving amount. So, what happened? Those who are processed meals consumed about 500 calories more per day to feel equally satiated, even though they ranked both the processed and freshly made food as equally tasty. That could add up to a lot of extra weight over the years, and in turn, chronic problems like joint pain, inflammation, and diabetes. Basically, as tasty as the processed food seemed, it just didn’t quite hit the spot.

how does processed food defeat portion control?

What the study shows us is that a calorie is not a calorie is not a calorie, and how our food is prepared and consumed matters. Processed food could come in what looks like a smaller portion, it may go down easier so we eat it faster, it can be more flavor dense so we lose track of how much we eat, or there might be some combination of all these things, but the result is that we just plain eat too much of it when it’s on our plates because we don’t feel full. Our phones might be able to scan a food and know exactly how many calories it’s reported to have as well as the right serving sizes, but our eyes, mouths, and stomachs can’t, going by taste, feel, and mood.

Ultra-processed food just plain confuses us about what a healthy portion is, and we pay for it in the end. Meanwhile, fresh food has no additives and it’s what we evolved to eat, so if we just listen to our guts, we tend to make better choices. Even worse, if that processed food has too much fat added to it to maintain its flavor after weeks or months in the freezer, the fatty acids deposit themselves in the brain and mess with a neural pathway associated with depression, according to a related study on mice that demonstrated why fatty, processed diets seem to make us depressed and lazy while damaging our ability to interpret hunger signals in a healthy way.

After being fed a fatty diet, the mice exhibited both the physical and chemical signs of depression and lethargy no matter how much or little weight they gained because the fatty molecules messed with protein kinase A, or PKA in their hypothalamus, the area of the brain responsible for hormone production, mood, and hunger. Of course, we’re not mice, but as fellow mammals we share the same regulatory pathways for hunger, sex, and fear, and many basic studies looking into how these parts of the brains work tend to translate quite well between the species. (It’s the track record of experimental longevity and clinical weight loss treatments that’s much iffier.)

but wait, it gets worse. much worse…

When we combine the findings of the two studies, we get the following grim picture. When we feel sad, stressed, or depressed, we turn to highly processed, fatty comfort foods, or rely on them to save time on cooking. We eat too much of them because it’s hard to feel satiated with what should be a healthy portion, and fatty acids mess with our brains, causing us to feel depressed in a vicious cycle while we just keep getting heavier, sicker, and sadder. More mass means we that have more cells and more joint inflammation, which means more chances for some form of cancer to develop as our weight gain suppresses the immune system.

And we need a strong, healthy immune system which is necessary to keep would-be cancers in check, and disrupts the flow of hormones, which allows more expressions of deleterious genes and disrupts the regulation of cell growth, increasing the attack surface for cancerous cells and lowering our defenses against them. So while weight gain from processed foods doesn’t cause cancers, it does make us more susceptible to them alongside other issues. Armed with the data from these experiments, we can see why cutting out processed foods helps us lose weight and speeds up conversion of fat to muscle, along with huge improvements in mood and libido.

See: Hall, D., et. al., (2019) Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake, Cell Metabolism, DOI: doi.org/10.1016/j.cmet.2019.05.008

Vagena, E., et. al., (2019) A high-fat diet promotes depression-like behavior in mice by suppressing hypothalamic PKA signaling, Translational Psychiatry (9) No. 141, DOI: 10.1038/s41398-019-0470-1