What is Insulin Resistance?
March 29, 2022

What is Insulin Resistance?

Insulin is a key hormone in the body made in the pancreas. It gets made in response to what we eat. When you eat a meal that has sugar/carbohydrates in it, insulin gets released into the bloodstream. Insulin’s job is to tell the cells to take up the sugar and use it as fuel.

If you drink a can of coke, a lot of insulin is secreted. If you eat a salad sandwich, a medium amount of insulin is secreted. If you eat a piece of chicken, a small amount of insulin will be secreted, and if you eat pork crackling, no insulin will be secreted. When you eat a large amount of sugar, the cells become saturated with fuel fast and don’t have room to take in anymore, so the excess sugar gets turned into fat.

Over a long period of time, if sugar is eaten in excess, and therefore insulin is made in large amounts and often, the body’s cells struggle to cope so they tune out insulin’s messages. This tuning out is called insulin resistance. Insulin resistance means your cells have a harder time using glucose for fuel and instead, preferentially turn it into fat.

How does high insulin impact your body?

In most women with PCOS, insulin creeps up because the body is trying to maintain tight control over blood glucose levels. This is due to increased visceral fat, high sugar intake and sedentary behaviour.

High insulin impacts your health in multiple ways:

  • Leads to high triglycerides (sugary blood fats)
  • Decreases your good cholesterol (HDL)
  • Increases the liver’s production of bad cholesterol (LDL)
  • Increases risk of fatty plaques in blood vessels
  • Increases salt and water retention leading to fluid retention and high blood pressure
  • Decreases intracellular energy production
  • Blocks thyroid hormone production
  • Increases depression
  • Stimulates sugar cravings
  • Leads to a drop in blood sugar resulting in dizziness, headaches, fatigue, brain fog, sweats, tremors, cravings and anxiety
  • Increases fat deposits in organs and around your belly
  • Fatigue with and after exercise
  • Increases oxidative stress and inflammation
  • Increases production of male sex hormones in women (androgens)
  • Disrupts oestrogen rhythm and leads to poor ovulation
  • Decreases follicle stimulation leading to poorly formed eggs
  • Upsets circadian rhythm, sleep and stress response

The evolution of insulin

Insulin responds to our lifestyle choices. It’s affected by food, exercise, sleep and sex. It works hand in hand with other hormones such as leptin (satiety), ghrelin (hunger), and cortisol (stress and sleep/wake cycle). 

Think back thousands of years, before modern agriculture and supermarkets, where we hunted for food. We needed a mechanism that laid down fat for storage, a way to regulate our metabolism, easy energy release, appetite suppression during times of famine and the ability to utilise feasting for maximal benefit. These four hormones work synergistically together to regulate energy for optimal survival and reproduction. 

During stress or famine, the species had ways to switch off reproduction, manage metabolism and work in survival mode until conditions were more favourable. We still have stress (arguably even more stress), but we rarely experience famine. So, these ancient hormonal regulation systems are adaptive to a more feast/famine way of life. 

Looking through an evolutionary lens, issues such as insulin resistance and leptin resistance make total sense as they are the body’s response to lowering reproduction and limiting energy usage. 

PCOS has evolved to be an evolutionary advantage - slightly reducing fertility and spacing offspring, leading to better chances of survival. PCOS women were evolutionarily advantaged, until processed foods arrived!

When we secrete insulin to regulate sugars, leptin gets released. However, because of the high sugar load in our diets, leptin can become impaired - resulting in leptin resistance, which can lead to significant sugar cravings.

If you want to lower those afternoon cravings, try having a low carbohydrate meal at lunch time. Think chicken and vegetables, lamb and salad, or a smoked salmon and egg omelette. 

By lowering grain carbohydrates, you will lower insulin release.

Dr Michelle Woolhouse

Integrative GP and Vively Medical Director

Dr Michelle Woolhouse is an integrative GP, with over 20 years experience treating chronic conditions through lifestyle medicine