Mid-afternoon, the day has dragged, and the biscuit tin is calling. Two biscuits later there's a flicker of comfort, then an hour after that you're flatter than before, a little tearful or snappy, and reaching for the tin again. Later, waiting for dinner, you bite someone's head off over nothing and apologise once you've eaten.
We treat food as comfort for a bad mood. The twist is that the biscuit may be part of why the afternoon went flat in the first place, and the foods that steady a mood sit in places the usual "superfood" lists rarely look.
The sugar rush that never arrives
The idea of a sugar rush is so familiar that it hardly ever gets questioned. When people's moods were measured after they ate sugar or other fast carbohydrates, pooled across dozens of experiments, the lift never showed up. Within the hour they were wearier and duller than people who'd had none, and their mood was no better.
Even the sugar high in children is partly in the watcher's eye. When boys aged five to seven, whose mothers called them "sugar sensitive", were all given a sugar-free drink, the mothers who had been told their son had just had a lot of sugar rated him as more hyperactive, stayed closer to him and criticised him more.
So why does the biscuit feel as if it works? Partly because, for a little while, it does. Sugary, fatty food quietens the body's stress system, and under long stress the brain comes to prize that relief more and more, which is how the habit takes hold. Women under long-term strain whose stress response had gone flat ate more chocolate cake from a buffet, whether or not they'd just been through a stressful task. The comfort is real and short, and what follows is the part that matters for how you feel for the rest of the afternoon.
One early use of the phrase "comfort food" is a 1966 newspaper story saying that adults under severe stress turn to food that recalls childhood, like a mother's poached egg or chicken soup. The first comfort foods, in other words, were eggs and broth. The Hidden Science of Sugar Cravings, linked below, explains why the pull is so strong.
Spikes, crashes and the hangry hour
Foods that turn quickly into glucose, sweets, pastries, white bread, crackers, breakfast cereal, juice, send blood sugar climbing fast. The body answers with a surge of insulin to bring it down, and it can overshoot. As blood sugar falls, the body releases adrenaline and cortisol to push it back up, and those are the same hormones that make you feel anxious, shaky and short-tempered.
That's why "hangry" is real, real enough to earn its place in the Oxford English Dictionary in 2018. When people tracked their hunger and mood through ordinary days, the hungrier they were, the angrier and more irritable they felt, and the less they enjoyed things. On a diet of fast carbohydrates, the hungry, irritable window comes round several times a day.
The sweets industry knows that feeling well. In 2010 Snickers launched its "You're Not You When You're Hungry" adverts, and the agency behind them said the campaign took it from seventh to the best-selling chocolate bar. The cure on offer for the hangry hour was a sugar bar, the same thing that sets up the next one.
Repeat it for weeks and the pattern starts to look like low mood. When the same healthy adults ate a diet built on fast carbohydrates for four weeks and a slower-burning one for another four, their depression scores were about a third higher on the fast-carb month. Across tens of thousands of older women followed for years, those whose diets raised blood sugar most sharply, heavy in added sugar and refined grains, were more likely to become depressed.
The glass that lifts and then drops
Alcohol feels like it lifts your mood, and for an hour or so it does. It's a depressant, though. About one person in eight wakes after drinking with anxiety on top of the headache, a feeling nicknamed hangxiety, and what causes it is still not pinned down. Over time, alcohol can bring on low mood or make it worse, both while you drink and when you stop.
The cup that runs your mood
Coffee plays a quieter version of the same trick. Go without it for a day and the body says so: when 66 tests of caffeine withdrawal were reviewed, the confirmed effects included low mood, feeling less content, irritability, tiredness and trouble concentrating, and half the people in the experiments got a headache.
That changes how the morning cup looks. When the careful experiments were weighed up, regular drinkers showed little or no real gain in mood or performance from their caffeine. What they felt was mostly the night's withdrawal being switched off. The cup only returns you to the mood you'd have had with no habit at all, and tomorrow the cycle starts again. How to Quit Coffee: Getting Through Caffeine Withdrawal has how to get off it with the least misery.
Ultra-processed food and a heavy mood
Ultra-processed foods are the ones made mostly from refined starch, sugar, cheap oils and additives: packaged snacks, sweet drinks, ready meals, most breakfast cereals, fast food. They're built to be eaten quickly and to leave you wanting more, and they hit blood sugar hard.
When the evidence on ultra-processed food was pulled together across dozens of large analyses, the links with depression and anxiety were among the strongest found for any health problem. People who ate the most of it were noticeably more likely to struggle with both.
The encouraging side of that finding comes from people who changed their plates. Adults with depression who spent three months swapping processed and fast food for simple, whole foods, with support to help them do it, saw their mood lift far more than a comparison group who received social support alone. About a third of the diet group recovered fully in that time, against roughly one in twelve of the others.
What your brain makes mood from
Feeding the mood is nothing new. In the second part of Don Quixote, published in 1615, his niece and housekeeper are told to give him things to eat that are "comforting and appropriate for the heart and the brain". The chemistry came much later. Your brain builds its mood chemicals from the food you eat. Serotonin, which steadies mood and sleep, is made from tryptophan, and dopamine, which drives motivation and pleasure, is made from tyrosine. Both are amino acids, the building blocks of protein, and meat, fish and eggs supply them in quantity.
You'll often read that the gut makes about 90 per cent of the body's serotonin, as if a happy gut sends it up to the brain. The gut does make that much, but it uses it there, to keep digestion moving. Brain serotonin stays on the other side of a protective barrier, and the brain builds its own supply from the tryptophan you eat.
The gut can still steer mood by other routes. In one test, people with depression carried a less varied mix of gut bacteria than healthy people, and when rats were given gut bacteria from the depressed patients, they lost interest in pleasure, grew more anxious and handled tryptophan differently. It's an animal finding, and one more reason to look after the gut with real food.
A breakfast of eggs, a lunch built on meat or fish, and a dinner with a good helping of protein give your brain a regular supply of raw materials, and they keep blood sugar calm at the same time. 7 Essential Nutrients Your Brain Craves, linked below, goes through the rest of what the brain runs on.
Oily fish, the fat your brain is built from
Much of your brain is fat, and a good share of that is omega-3, the kind oily fish carry: salmon, sardines, mackerel, herring and anchovies. It sits in the walls of brain cells, where it helps messages pass smoothly and keeps inflammation in check.
The type of omega-3 matters for mood. Oily fish supply two main kinds, and the one called EPA does the heavy lifting: in comparisons with dummy capsules, omega-3 rich in EPA eased depression, while the other kind on its own did little. The plant form in flaxseed and walnuts has to be converted by the body, which does so poorly, so fish and seafood are the direct route. Tinned fish makes it easy: a tin of or a pack of is lunch the moment the lid comes off.
The quiet shortfalls
Some low moods have an ordinary cause, a nutrient the brain needs that's running short. The simplest one is water. Losing a little over 1 percent of body weight as fluid, easy on a warm day or a busy one, was enough to lower young women's mood, energy and concentration and bring on headaches, even while they sat at rest.
Vitamin B12 keeps nerves and brain working, and low levels bring tiredness, low mood and poor concentration. Animal foods are its only reliable source, so a vegan or vegetarian diet runs low easily, and so can older age and years of reflux tablets or metformin for blood sugar.
Iron carries oxygen to the brain, and heavy periods are a common way to run short, often well before it shows up as anaemia, with a flat, tired, irritable feeling that gets blamed on stress. Red meat and liver carry haem iron, which the body absorbs more easily than the iron in plants.
Zinc and vitamin D round out the list. Low zinc goes with low mood, and red meat and shellfish are its best sources. Vitamin D runs low through the darker months, and low levels have been linked with low mood, though whether topping it up lifts mood is still unclear. All four can be measured in the blood, and vitamin D can even be checked at home with an at-home test kit. Correcting a real shortfall can lift a mood that nothing else touched.
Creatine is the surprise on this list. It's famous in the gym, but the brain also keeps it as a fast-access energy store, and meat and fish are where it comes from in food. When it was added to antidepressant treatment in women with depression, their mood improved faster and further than in women given a dummy capsule, with the difference showing from the second week. It's early work, and it adds to the case that the brain does well on what animal foods supply.
That case shows up in plant-only diets too. When the evidence was pooled, vegans and vegetarians had around twice the odds of depression, though their anxiety scores were a little lower, and comparisons like these leave open which comes first. B12, iron, omega-3 and creatine all run low on plants alone, so eating that way is extra reason to have your levels tested.
Keto, carnivore, fasting and the mind
Eating low-carb, keto-style, takes the spikes and crashes out altogether, and some of the most striking results in food and mental health come from doing just that. In a hospital where people with severe depression and other serious mental illnesses, all of whom had struggled for years, were fed a ketogenic diet, their depression scores fell by around two-thirds over the weeks they stayed. A small pilot in people with bipolar disorder and schizophrenia saw their symptoms ease alongside big improvements in weight and blood sugar.
The likely reasons are the even supply of fuel, the ketones themselves, which the brain uses easily, and calmer inflammation and insulin. Take the crash away and the hangry hour has nothing left to run on, which is much of the case for keto and carnivore eating as a steadier way to feel. makes the full case for the meat-based version.
Fasting works on the same lever. Going longer between meals lets insulin fall and the body turn to its own fat for fuel, and fasting clinics have long noticed sharper alertness and a lifted mood in their patients once the first days have passed. Hunger in those first days can bring its own irritability, and that tends to fade as the body gets used to running on fat. If you've ever struggled with an eating disorder, fasting and strict food rules can pull you back towards it, so keep your meals regular and make any change with support around you.
The keto results so far come from small, early groups, and a serious mental illness needs proper care alongside any change of diet. Medicines for mood, blood pressure and blood sugar can all need adjusting when carbohydrates drop, so any big change should happen with whoever prescribes them.
Whichever way you cut back on sugar and starch, expect a bumpy few days first. Cravings, a dull headache and a shorter fuse often turn up at the start, partly because the body lets go of salt and water while it changes fuel, and that's the point where it's tempting to give up and go back to the biscuit tin. Push through that stretch, with protein at every meal, water, and a little extra good-quality unrefined salt, and mood tends to settle into something steadier than before. That's experience rather than a measured finding, and knowing it helps on the day you most want to give up.
When food is part of the answer
Food can steady a mood, but it works alongside everything else: sleep, daylight, movement, people. If your mood has stayed low for weeks, the things you loved have gone flat, or you're thinking about harming yourself, please reach out for help now. Better food can support recovery, and it's no substitute for support when you need it.
Feed the mood you want
The comfort in the biscuit is real, and it's short. What follows costs you the rest of the afternoon: a flatter mood by teatime and a short temper before dinner. What keeps a mood level is what keeps blood sugar level and gives your brain the raw materials it builds mood from: meat, fish and eggs, with less of the sugar, flour and packets in between.
So start with breakfast this week. Swap the cereal or toast for eggs, and notice how you feel mid-morning and again mid-afternoon. That one swap can show how much of a bad afternoon was on the plate all along. And the apology before dinner may turn out to be one you no longer need to make.
Wondering why the biscuit tin keeps calling? The Hidden Science of Sugar Cravings — what drives the pull towards sugar, and how to get free of it.
Want the nutrients behind a sharper mind as well as a steadier mood? 7 Essential Nutrients Your Brain Craves—and How to Harness Their Power for a Sharper Mind — the fats, proteins and minerals the brain runs on.
Know someone who reaches for something sweet every afternoon and wonders why they feel worse? Pass this on. Their answer may be sitting on the breakfast plate.
Tried something here, or got a question it didn't answer? Write to us at contact@allforlife.club. Your questions shape the next articles.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If your mood has stayed low for weeks, the things you loved have gone flat, or you're thinking about harming yourself, reach out for help today. If you take medicine for mood, blood pressure or blood sugar, talk to whoever prescribes it before making big changes to what you eat.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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