The Three Hidden Forces That Shape What You Eat (And What Your Brain Actually Needs)

This article explains what really drives your food choices, how your brain interprets hunger and nutrition, and what you can do to align what you eat with what your brain actually needs.

Someone asks me what they should eat for brain health, and I usually start by admitting something uncomfortable: most of what we think we know about food and the brain is incomplete. Not wrong, necessarily. Just... partial.

Omega-3 vs. Omega-6 Fatty Acids - What Your Brain Needs

Fatty Acid Type	Primary Brain Function	Optimal Daily Intake	Best Food Sources	Common Problem
Omega-3 (EPA/DHA)	Forms neuronal membranes, reduces inflammation, supports mood regulation and cognition	500 mg minimum (Australian guidelines); 2-3 grams for cognitive benefits	Fatty fish (salmon, mackerel, sardines), algae supplements, chia seeds, flaxseeds, walnuts	Most Western diets are deficient; difficult to get adequate amounts without fish or supplementation
Omega-6	Cell membrane structure, pro-inflammatory signaling (in balance)	No supplementation needed	Vegetable oils, processed foods, nuts, seeds	Excessive intake from processed foods; creates inflammatory imbalance when omega-3s are low

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The Three Hidden Signals That Control Your Food Choices

1. Gut Neuron Signaling (Enteric Nervous System)
2. How it works: Chemical sensors in your gut detect amino acids, fatty acids, and glucose, sending signals directly to your brainstem
3. What it controls: Unconscious cravings, satiety signals, future food preferences

4. Awareness level: Completely unconscious - you never feel this happening

5. Metabolic Accessibility to the Brain

6. How it works: Your brain tracks how quickly different foods convert to usable energy (glucose and ketones cross the blood-brain barrier most efficiently)
7. What it controls: Energy-based cravings, preference for quick-fuel foods during cognitive demand

8. Awareness level: Subconscious - felt as energy levels and food "pull"

9. Belief and Expectation

10. How it works: What you think food contains changes actual metabolic signaling and body response
11. What it controls: Metabolic response, satiety hormones, nutrient partitioning
12. Awareness level: Conscious but unrecognized - your beliefs alter physiology even when macronutrient content is identical

I've been reading more about the neuroscience of eating lately - Andrew Huberman's work, some of the newer metabolic research, papers on gut-brain signaling that came out in 2023 and 2024. What strikes me is how much of our food behavior happens outside conscious awareness. We think we choose what we eat. Mostly, we don't.

The Three Signals No One Talks About

There are three separate systems driving your food choices, and only one of them involves what you think you're choosing.

The first signal is gut neurons - enteric neurons, technically - sending information directly to your brainstem about nutrient content. You're completely unaware of this. These neurons detect amino acids, fatty acids, glucose concentration. They're essentially chemical sensors reporting back to central command. You never feel this happening. But it shapes cravings, satiety, and what your body "wants" next time you open the fridge.

The second signal is metabolic accessibility. How readily a given food converts into usable energy for your brain. Not your muscles, not your liver - your brain specifically. Glucose crosses the blood-brain barrier easily. Ketones do too, when they're around. Some nutrients take longer routes. Your brain tracks this efficiency and nudges you toward foods that deliver energy quickly when it needs it.

The third signal - this one's strange - is belief. What you think the food contains. What you expect it will do for you. There's research showing that if you believe a meal is high-protein, your body responds differently than if you think it's high-carb, even when the actual macronutrient content is identical. Belief changes metabolic signaling. I'm still working out what to do with that information.

What Actually Makes Up Your Brain (It's Not What You Think)

Before we even get to fuel - glucose, ketones, all that - we need to talk about structure. What neurons are made of.

The answer, surprisingly, is fat.

Not the fat around your abdomen or under your skin. Structural fat. The kind that forms cell membranes - thin double-layered boundaries that wrap around every neuron and glial cell in your brain. These membranes aren't just packaging. They regulate electrical activity, control what crosses into and out of the cell, determine how neurons fire and communicate.

If those membranes degrade, neuronal function degrades with them.

The fats that make up these membranes are called essential fatty acids and phospholipids. Your body can't make them from scratch. You have to eat them. And most people - especially those not eating fish regularly - aren't getting enough of the right kinds.

Omega-3s: EPA and DHA

Omega-3 fatty acids, particularly EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are probably the most evidence-backed nutrients for brain structure and function. Large reviews and meta-analyses consistently show benefits for cognition, mood regulation, and long-term brain health.

The Australian guidelines suggest at least 500 mg combined EPA/DHA daily. More recent research - particularly studies from 2023 looking at cognitive decline - suggests benefits continue up to 2-3 grams daily, especially for EPA.

Most people eating Western diets get plenty of omega-6s (from vegetable oils, processed foods, nuts). It's the omega-3s they're missing.

Sources of omega-3s:
- Fatty fish (salmon, mackerel, sardines) - by far the richest source
- Chia seeds
- Flaxseeds
- Walnuts
- Soybeans
- Algae-based supplements (for those avoiding fish)

I don't eat fish every day. Most people don't. That's one reason supplementation often makes sense - not as replacement, but as insurance. The evidence for EPA supplementation improving mood and cognitive function is solid enough that I personally take it and recommend it to patients fairly often, especially those with low dietary intake.

Phosphatidylserine: The Other Structural Fat

Phosphatidylserine is another phospholipid - a fat molecule with a phosphate group attached - that's abundant in neuronal membranes. It supports cell signaling and membrane fluidity. There's some evidence it improves memory and reduces cognitive decline in older adults, though the data is less robust than for omega-3s.

You get phosphatidylserine from meat and fish primarily. For vegetarians or people not eating much animal protein, supplementation is available, usually derived from soy or sunflower lecithin.

I don't push this one as hard as omega-3s. The evidence is decent, not overwhelming. But for someone already supplementing omega-3s and still concerned about cognition, it's worth considering.

Choline: The Focus Molecule

Choline is the third nutrient I think about when someone asks about brain health. It's a precursor to acetylcholine - a neuromodulator (not a neurotransmitter, technically, though that distinction mostly matters to neuroscientists) that acts like a cognitive highlighter. It sharpens focus, consolidates memory, and enhances attention.

Acetylcholine is why medications like donepezil (used in Alzheimer's disease) work - they block acetylcholine breakdown, increasing its availability in the brain.

Most people need about 500-1,000 mg of choline daily. The richest dietary source, by far, is egg yolks. One large egg contains roughly 150 mg. Two or three eggs gets you halfway there.

For people who don't eat eggs - vegetarians, vegans, or those with allergies - choline comes from potatoes, nuts, seeds, grains, and some fruits, though in much smaller amounts. Supplementation with choline bitartrate or CDP-choline (citicoline) is common in nootropic circles, and the evidence for cognitive benefit is reasonable, especially in older adults or people with low dietary intake.

I used to avoid egg yolks because of cholesterol concerns. Turns out that was mostly unfounded - dietary cholesterol doesn't significantly raise blood cholesterol in most people. A 2023 meta-analysis confirmed eggs don't increase cardiovascular risk in healthy individuals. So now I eat them fairly often. The choline content alone justifies it.

Creatine: Not Just for Muscles

Creatine is mostly known as a supplement for gym-goers - muscle mass, strength, hydration. But it also functions as a fuel source in the brain.

Creatine phosphate donates phosphate groups to regenerate ATP (adenosine triphosphate) - the cellular energy currency. Neurons, especially in high-demand areas like the prefrontal cortex, use a lot of ATP. Creatine helps keep that system running smoothly.

There's also emerging evidence - mostly from studies in 2022-2024 - that creatine improves mood, particularly in people with depression, and enhances working memory and executive function, especially in vegetarians and older adults (who often have lower baseline creatine stores).

The standard dose is 5 grams daily of creatine monohydrate. You get creatine from meat, but unless you're eating large amounts regularly, supplementation makes sense. Vegetarians and vegans, in particular, tend to see noticeable cognitive benefits from supplementation because they have zero dietary intake.

I take 5 grams daily. Have for years. I can't say I notice a dramatic difference, but I also haven't gone off it to see what happens. I think of it more as baseline maintenance than acute performance enhancement.

Glucose: The Brain's Primary Fuel (With Caveats)

After structure, we get to fuel. The brain uses about 20% of your total energy expenditure despite being only 2% of body weight. It runs almost entirely on glucose under normal conditions.

When blood sugar drops too low - hypoglycemia - cognitive function deteriorates fast. Confusion, irritability, difficulty concentrating. Severe hypoglycemia can cause seizures or loss of consciousness.

But here's the thing: stable, moderate glucose is ideal. Chronic hyperglycemia (high blood sugar) damages blood vessels, including those in the brain, and increases risk of dementia and cognitive decline. Insulin resistance - common in prediabetes and type 2 diabetes - also impairs brain function over time.

The goal isn't to maximize glucose intake. It's to maintain steady supply without chronic spikes.

That means:
- Prioritizing complex carbohydrates (whole grains, legumes, vegetables) over refined sugars
- Pairing carbs with protein and fat to slow absorption
- Avoiding large blood sugar swings (which often come from processed foods, sugary drinks, or eating carbs in isolation)

I've noticed people often think "more glucose = better brain function." That's not quite right. It's about stability, not quantity.

Ketones: The Alternative Fuel

When glucose is scarce - during fasting, ketogenic diets, or prolonged exercise - the liver produces ketone bodies (beta-hydroxybutyrate, acetoacetate, acetone) from fat breakdown. These cross the blood-brain barrier and neurons can use them for energy.

There's growing interest in ketones for neuroprotection, particularly in epilepsy, Alzheimer's, and traumatic brain injury. Some evidence suggests ketones provide more stable energy than glucose and reduce oxidative stress in neurons.

I'm cautious about overstating this. Ketogenic diets aren't magic, and they're not appropriate for everyone. But for certain conditions - especially refractory epilepsy - they're effective. The data for cognitive enhancement in healthy adults is mixed.

Some people feel sharper on low-carb or ketogenic diets. Others feel worse. Probably depends on individual metabolism, genetics, and what you're comparing it to.

The Belief Signal (The Strangest One)

This is where it gets weird.

There are studies - some from 2023, some earlier - showing that what you believe about a food changes how your body responds to it. One study gave participants identical milkshakes but labeled them differently: "high-protein" vs "high-carb." The group told they were drinking high-protein had different hormonal responses (ghrelin, insulin) than the group told high-carb, even though the macros were the same.

Your brain's predictions about a food alter metabolic processing. Belief isn't just psychological. It's physiological.

I don't know what to do with this yet. It complicates everything. Are we optimizing nutrition, or are we optimizing belief systems about nutrition? Maybe both.

Some days I think we overthink all of this. Other days I think we're barely scratching the surface.

What I Actually Tell People

When someone asks me what to eat for brain health, I usually say:

1. Get omega-3s: Either from fish (2-3 servings weekly) or supplement with 1.5-3 grams EPA/DHA daily.
2. Eat eggs if you can: The choline content alone justifies it. If you can't, consider supplementing.
3. Consider creatine: Especially if you're vegetarian, older, or notice brain fog. 5 grams daily.
4. Stabilize blood sugar: Complex carbs, protein, healthy fats. Avoid chronic spikes.
5. Don't obsess: Most of nutrition's effect on the brain is long-term and structural. Day-to-day variation matters less than consistency.

I'm still learning what all this means. Most of us are. The science is evolving, and I suspect we'll look back in ten years and realize we were missing something obvious.

But for now, these seem like reasonable starting points. What do you think?