Understanding Insulin Resistance and Your Mental Health

If you've ever wondered why you feel mentally exhausted after eating certain foods, or why your mood seems to crash a few hours after a meal, the answer might lie in understanding insulin resistance. This metabolic condition affects millions of young people today, yet most don't realise how profoundly it impacts their ability to think clearly, regulate emotions, and maintain stable energy throughout the day.

In my clinical practice, I regularly meet young adults presenting with symptoms of brain fog, mood instability, apathy and fatigue. Many show clear signs of insulin resistance or prediabetes, yet they have no idea that their daily food choices are directly contributing to both their mental and physical health struggles. They've been taught to count calories but never learned that food quality fundamentally shapes how their brain and body function.

Understanding insulin resistance reveals why what you eat matters far more than how much you eat.

What Is Insulin Resistance?

Think of insulin as a key that unlocks your cells to let glucose (blood sugar) inside for energy. In insulin resistance, your cells become like rusty locks that are hard to open. Your pancreas responds by making more insulin keys, but the locks just get rustier over time.

This creates several problems: your blood sugar stays high longer than it should, your pancreas becomes overworked, your cells become starved of fuel even though there's plenty of glucose in your blood, and your body starts storing excess glucose as fat whilst making it harder to burn stored fat for energy.

For young people, this often develops gradually. You might notice difficulty concentrating during afternoon classes, mood swings that seem disproportionate to what's happening, persistent cravings for sugary foods, or feeling tired despite getting enough sleep. These symptoms are often dismissed as normal teenage experiences or school stress, but they frequently signal underlying metabolic dysfunction.

Your Brain and Insulin Resistance

Your brain uses about 20% of your body's total energy despite being only 2% of your body weight. When insulin resistance develops, your brain's ability to efficiently use glucose becomes compromised. This leads to what researchers call cerebral glucose hypometabolism, which is a fancy way of saying your brain isn't getting the fuel it needs to work properly.

The effects on your mental function are significant. Memory consolidation, the process of moving information from short-term to long-term memory, becomes impaired. This explains why students with insulin resistance often struggle to retain information they've studied, even when they understand it initially. Attention and focus suffer as your prefrontal cortex, responsible for executive function, struggles with inconsistent energy supply.

Perhaps most importantly for young people, emotional regulation becomes increasingly difficult. Your limbic system, which processes emotions, becomes hypersensitive when energy supply is inconsistent. This leads to mood swings, increased anxiety, irritability, and difficulty managing stress that would normally be manageable.

The Modern Food Trap

Here's what most young people don't realise: the majority of food available in shopping centres, school canteens, and convenience stores is specifically designed to create insulin resistance and metabolic dysfunction. Walk through any food court and you'll find that most options combine refined sugars with inflammatory processed oils, creating what food scientists call "hyperpalatable" products.

These foods are engineered to override your natural appetite signals and create cravings. Consider what's typically available to teenagers: energy drinks containing 35-40 grams of sugar (that's about 10 teaspoons), muffins and pastries made with refined flour and vegetable oils, snack foods combining starches with inflammatory fats, and even supposedly "healthy" options like fruit juices that contain more sugar than soft drinks.

The food industry spends billions researching the exact combinations of sugar, salt, and fat that create the strongest cravings. This isn't accidental; it's a deliberate strategy to encourage repeated consumption. Understanding this helps explain why willpower alone often fails when trying to make healthier choices.

Quality Beats Quantity

The old approach to nutrition focused on "calories in versus calories out," suggesting all calories are basically the same. This completely ignores how different foods affect your hormones, particularly insulin.

When you eat foods that spike insulin rapidly, your body shifts into fat storage mode whilst simultaneously making stored fat difficult to access. High insulin levels activate enzymes that create fat whilst blocking enzymes that burn fat. This creates a metabolic trap where you can feel hungry and tired even when carrying excess body fat.

Compare this to foods that maintain stable blood sugar and insulin levels. These allow your body to efficiently access both dietary and stored energy sources. You maintain stable energy and mood throughout the day without constantly needing to eat, and you naturally feel satisfied with appropriate portions rather than fighting constant cravings.

Quality foods also provide the vitamins, minerals, and cofactors necessary for healthy insulin function. Magnesium, chromium, zinc, and B vitamins all play crucial roles in glucose metabolism. Processed foods are stripped of these nutrients during manufacturing, creating a situation where you consume calories without the micronutrients needed to properly process them.

The Inflammatory Factor

Modern processed foods don't just spike insulin; they also promote inflammation throughout your body. Refined seed oils, found in virtually all processed foods, are high in omega-6 fatty acids that convert to inflammatory compounds. These oils also oxidise easily during processing and cooking, creating harmful compounds that worsen inflammation.

This chronic inflammation directly contributes to insulin resistance whilst also affecting brain function independently. Inflammatory molecules can cross the blood barrier, triggering brain inflammation that impairs neurotransmitter production and function. This explains why people eating highly processed diets often experience symptoms resembling depression, anxiety, and cognitive dysfunction.

The combination of insulin resistance and chronic inflammation creates a vicious cycle. Insulin resistance promotes inflammation, whilst inflammation worsens insulin resistance. Breaking this cycle requires addressing both the foods that spike insulin and those that promote inflammation.

The Blood Sugar Roller Coaster

To understand why food quality matters so much, imagine two different breakfast scenarios. Scenario one: you grab a muffin and fruit juice on your way to school. Within 30 minutes, your blood sugar spikes dramatically, triggering a massive insulin release. You feel energised and alert initially, but by mid morning, your blood sugar crashes below normal levels. You feel tired, irritable, and unable to concentrate. Your brain, desperate for fuel, triggers strong cravings for more sugary foods.

Scenario two: you eat eggs with avocado for breakfast. Your blood sugar rises gently and stays stable for hours. Insulin levels remain low and steady. You maintain consistent energy and focus throughout the morning, your mood stays stable, and you don't experience cravings. When lunch time arrives, you're appropriately hungry but not desperately so.

This difference in blood sugar patterns explains why some foods leave you feeling great whilst others make you feel terrible, regardless of how many calories they contain.

Practical Solutions for Real Life

Understanding insulin resistance empowers you to make choices that support rather than undermine your mental performance. Focus on foods that provide stable energy: quality proteins like eggs, fish, and meat and natural fats from sources like meat, fish, avocados and nuts.

When you do choose higher carbohydrate foods, combine them with protein and healthy fats to slow absorption. This means having cream with fruit, adding eggs to your breakfast, or including avocado with meals containing starches.

Timing also matters. Your insulin sensitivity is generally highest in the morning and lowest in the evening. Eating high-carbohydrate meals late into the evening is a recipe for insulin resistance and fatigue.

Most importantly, recognise that the food environment around you is largely designed to promote metabolic dysfunction. Reading ingredient lists becomes crucial; if you see high fructose corn syrup, vegetable oils, or ingredients you can't pronounce, these are red flags. Unfortunately, there are more than 60 different terms for sugary sweeteners in Australian food products. Preparing more meals at home, even simple ones, gives you control over ingredients.

Taking Back Control

Understanding insulin resistance fundamentally changes how you think about food. Instead of viewing it as simply fuel measured in calories, you begin to recognise food as information that directs your body's metabolic processes. When you choose foods that support healthy insulin sensitivity, you're optimising your brain function, emotional regulation, and overall quality of life.

This knowledge is particularly powerful for young people because it explains why certain foods make you feel terrible whilst others provide sustained energy and mental clarity.

It's not about restriction, it's about understanding how different foods affect your body and making choices that align with your goals.

The metabolic flexibility that comes from reversing insulin resistance means better academic performance, more stable moods, improved sleep quality, and the energy to pursue activities you enjoy. Most importantly, it means taking control of your health in a food environment that's specifically designed to undermine it.

Your brain deserves better than the blood sugar roller coaster that comes from processed foods. By understanding insulin resistance and making informed food choices, you can maintain the stable energy and clear thinking that allows you to perform at your best, both academically and personally.