What Causes Insulin Resistance?
- Mar 03, 2021
Before understanding Insulin Resistance, it is important to understand how insulin normally helps to regulate glucose levels in the blood.
When we eat food that gets digested by enzymes in our gut, glucose is absorbed through the gut into the bloodstream. As the concentration of glucose in our blood starts to rise, the pancreas is stimulated to release insulin into the blood. The insulin goes to various cells in our body, including our muscle cells, liver cells, heart, and brain in order to facilitate the uptake of glucose into these cells. It does this by attaching to an Insulin Receptor on the cell membranes of these cells. Once this attachment has taken place, several downstream reactions need to take place before the glucose is transported into the cells via a channel in the cell membrane. As glucose concentration levels in the blood fall, the insulin levels fall back down as well.
This is analogous to someone needing to go into a room. If the person needing to go into the room was the glucose, the key they insert into the lock would be the insulin attaching to the insulin receptor, the turning of the lock would be the downstream reactions taking place, and the opening of the door would be the insertion of the channel to allow the glucose in.
In a state of insulin resistance, once the insulin attaches to the insulin receptor, the downstream reactions required to facilitate the transport of glucose are impaired which leads to the glucose not being taken up by the cells.
Initially, the pancreas responds by making more insulin to overcome the resistance and this can work for a number of years, but eventually, the resistance builds up too much and/or the pancreas starts to lose its ability to secrete insulin. This results in blood glucose levels rising past the threshold and the patient is now considered to have diabetes.
There are several known contributors to insulin resistance:
- Intracellular fat – Free fatty acids that accumulate in the muscle and liver cells inhibit the proper working of the insulin receptor. These free fatty acids are thought to be the result of a diet that is high in processed sugars (fructose) and high in saturated fats. These free fatty acids can also spillover from increased adipose tissue.
- Heme Iron – This is the iron that is found in red meat. It is readily absorbable but has recently been implicated in the formation of insulin resistance.
- Advanced Glycation End-products – Known as AGEs, these are the resulting products of protein and carbohydrates reacting together when food is cooked at high temperatures. They occur in animal products at much higher rates than in plant foods.
- Chronic Stress – chronically elevated cortisol levels – leads to elevated insulin requirements.
- Poor sleep – people who have a shorter duration of restorative sleep wake up with higher levels of cortisol which in turn increases insulin requirements.
A lifestyle that focuses on incorporating whole-food plant-based nutrition, at least 150 minutes of physical activity per week, mindfulness and meditation as stress reduction activities, regularly sleeping for 7 hours per night, and connecting with others, is the optimal method of reversing insulin resistance as many of the known causes of insulin resistance can be reversed.
Using Lifestyle Medicine to reverse insulin resistance is preferred over pharmacotherapy because currently there is no pharmacotherapy that directly deals with insulin resistance – only the complications. Oftentimes patients being treated with pharmacotherapy then have to be treated for the complications of the pharmacotherapy itself.
Insulin resistance is the main cause of Type 2 diabetes and associated with many of the cardio-metabolic conditions, including NAFLD, Dyslipidemia, Hypertension, Obesity, and Stroke, Coronary Artery Disease.