French Fries and Your Brain: What an 11-Year Study of 140,000 People Found About Fried Food and Mood

Picture the smell of fries fresh out of the fryer — golden, crackling, impossible to walk past. Now picture that same craving, examined not by a chef but by scientists watching more than 140,000 people for over a decade. What they found doesn't mean fries are "bad." But it does raise a question worth sitting with: could something we treat as pure comfort food also be quietly nudging our mood in the wrong direction?

Statistically, the average European eats around 7 kilograms of fried potatoes a year, and Americans eat even more — roughly 13 kilograms. Behind that crispy crust lies a question science has only recently started taking seriously: can regularly eating fried food, French fries in particular, affect not just the body but also our mood and mental wellbeing?

One home cook we came across put it simply after cutting back on fried food for a few weeks: she said she hadn't expected much, but noticed she felt steadier and less "foggy" by the afternoon, and slept a little better too. It's the kind of small, personal observation that doesn't prove anything on its own — but it's exactly the kind of pattern that led researchers to look closer.

What the research actually found

In 2023, a team from Zhejiang University in China published a large study in the journal Proceedings of the National Academy of Sciences (PNAS). Drawing on UK Biobank data, the researchers followed more than 140,000 people for 11 years and recorded 8,294 cases of anxiety and 12,735 cases of depression over that period. People who regularly ate fried food had, on average, a 12% higher likelihood of developing anxiety and a 7% higher likelihood of developing depression compared with those who rarely did.

The group most affected tended to be younger adults and men, often smokers, and people who also had a higher body mass index, lower household income, and less formal education. In other words, fries themselves are rarely the whole story — they're often just one piece of a wider lifestyle picture that can influence health in several ways at once. As WebMD reported, at least one independent expert cautioned that the causal arrow could run in either direction — people already struggling with anxiety or depression may simply reach for comfort food more often.

Our sister publication has covered this same study in more depth — see Does French fries really increase the risk of anxiety and depression? for a closer look at the numbers and what nutrition experts make of them.

What is acrylamide, and why does it matter?

When potatoes or other starchy foods are fried at very high temperatures, a compound called acrylamide forms. It isn't present in raw potatoes — it's created through the Maillard reaction, the same chemical browning process that gives fried and roasted food its color and flavor, typically once temperatures climb above 120{-15696}C.

Researchers believe acrylamide may contribute to low-grade inflammation in the brain and nervous system, which could help explain a link with mood difficulties, though the exact mechanism is still being studied. The European Food Safety Authority (EFSA) concluded back in 2015 that, based on animal studies, acrylamide potentially increases cancer risk and may affect the nervous system over the long term, while noting that evidence from human studies remains more limited.

Proving a direct, one-to-one link between French fries and depression is genuinely difficult — human mood is shaped by dozens of interacting factors. But many researchers now see mild brain inflammation as one plausible piece of the puzzle, rather than the whole explanation.

Anxiety and depression: a 21st-century challenge

According to the World Health Organization, an estimated 280 million people worldwide live with depression, and a similar number live with an anxiety disorder — together touching roughly one in ten people on the planet.

Set alongside the rise in fast-food delivery and convenience eating over the past several years, it's easy to see why researchers are paying closer attention to the relationship between what's on our plate and how we feel.

Why fried food may be as much a "head" issue as a "body" one

Fried food has long been recognized as a risk factor for weight gain, type 2 diabetes, and heart disease. What's newer is the growing interest in whether its effects reach further — into the brain itself. A serving of fries delivers plenty of calories, fat, and salt, but comparatively few vitamins and minerals.

On top of that, frying triggers chemical changes that produce acrylamide and other compounds that may, over time, place extra stress on cells. Put together, this combination may leave some people feeling more tired, low on energy, or flatter in mood — though, again, this is an association seen across large groups of people, not a guaranteed individual outcome.

A 2023 study from Uppsala University, published in the journal Obesity, found that after a week on a less healthy diet, participants' deep sleep quality noticeably declined compared with a week on a healthier diet — even though total sleep time stayed the same. Since deep sleep is one of the pillars of good mental wellbeing, this is a useful reminder that diet and rest are closely intertwined.

Why a total ban isn't the answer

It's worth being clear-eyed here: fries are not, on their own, a "villain." Depression and anxiety are what researchers call multifactorial conditions — shaped by a mix of genetics, stress, sleep, life circumstances, and yes, diet among many other things. Dr. Nicole Lippman-Barile, a clinical psychologist specializing in nutritional psychology quoted in Foodwhisper's coverage of the same study, stresses that no single food is directly responsible for a mental health condition, and that a balanced overall approach matters far more than any one meal.

So an occasional portion of fries is not going to "cause" depression on its own. The concern researchers raise is specifically about fried food being an everyday, default part of someone's diet — frequency and pattern, not the occasional treat.

Simple, affordable ways to enjoy fries a little smarter

The encouraging part is that there are easy, inexpensive ways to keep enjoying potatoes without the same trade-offs. Instead of deep-frying, you can:

• Bake them in the oven at a moderate temperature instead of deep-frying;


• Use an air fryer, which typically needs a fraction of the oil that deep-frying does;


• Soak raw potato pieces in water before cooking, which helps reduce acrylamide formation.

On that last point, research from Leatherhead Food International, published in the Journal of the Science of Food and Agriculture, found that simply soaking raw fries in water for 30 minutes to 2 hours cut acrylamide formation by roughly a quarter to nearly half, as long as the fries were fried to a lighter, rather than dark, color.

It also helps to round out meals with foods that support a calmer, steadier system — leafy greens like rocket and spinach, nuts, whole grains, and oily fish. A large meta-analysis covering dozens of studies, associated with researchers at University College London and reported by CNN, found that people who most closely followed a Mediterranean-style diet had around a 33% lower likelihood of being diagnosed with depression compared with those who followed it least.

A real-world snapshot

Looking back at the past several years offers a useful, if informal, illustration of how closely eating patterns and mood can travel together. During the COVID-19 pandemic, many people leaned more heavily on comfort food and takeout. One 2020 U.S. survey found that two in three people were reaching for childhood comfort favorites more often, with French fries among the foods people turned to most — and a peer-reviewed study published in the journal Nutrients found that people's comfort food consumption during the pandemic tracked closely with their level of emotional distress at the time.

None of this proves that fries themselves drove anyone's mood down — distress and comfort eating clearly reinforce each other in both directions. But it's a fair reminder that our eating habits and our emotional state rarely move in isolation from one another.

Fries in moderation, mental health as the priority

Fries can be a genuinely enjoyable, occasional pleasure — and also a useful prompt to think about what regularly ends up on our plate. Frequent fried food consumption has been associated with a somewhat higher likelihood of anxiety and low mood in large studies, likely connected in part to acrylamide and to fried food's broader effects on the body.

The takeaway isn't to swear off fries forever. It's moderation, smarter preparation, and pairing them with foods that support both body and mind — so you can still enjoy your favorite dish without it working against your long-term wellbeing.