What role does insulin play in fat storage? Training to combat insulin resistance.

My role as a personal trainer regularly leads me to focus on weight loss, or as I prefer the term, fat loss. Ninety percent of my personal training clients rely on me for training and nutritional advice for the sole purpose of decreasing their body fat percentage and ultimately looking better. Although these are both worthy goals, I prefer to focus on improving their overall health for changes in body composition to be sustained throughout their lives. So how do we do that? We focus on insulin.

Insulin is an anabolic hormone that is released from the pancreas. It is released in response to rising blood glucose levels which occur following the ingestion of carbohydrates, fats and proteins (macronutrients). The amount of insulin released varies significantly depending on the amount of carbohydrates consumed. A large consumption of carbohydrates elevates the level of glucose in the blood which, after being detected by the pancreas, increases the amount of insulin released. Insulin activates transporter proteins called GLUT 4 (glucose-transporter 4) at the surface of the cell membrane which in turn enables glucose to move freely into the cell through the protein channel.

Still with me? Let’s take a look at a diagram showing the 6 steps of the insulin mechanism.

insulin 1

1. Blood insulin is elevated and binds to the receptor sights on the cell membrane. This activates processes within the cell itself.
2. GLUT 4 transporter proteins move from within the cell and integrate themselves onto the cell membranes. Once they’re on the membrane, the channels that these proteins have are able to open.
3. Due to the high concentrations of glucose in the bloodstream, this allows the natural movements of glucose from outside the cell, through the channel, into the cell. Once glucose is inside the cell, there can be 3 resulting outcomes.
4. Firstly, glucose can be stored as glycogen for later use.
5. Secondly, glucose is stored as pyruvate which is a substance that forms the basis of aerobic metabolism (one of the bodies’ main energy pathways).
6. Lastly, it can be converted to fatty acids.
In normal, healthy individuals, glucose is taken up by the blood stream and moved into the interior cells where it is used as fuel. This whole process is of course mediated by insulin. So what happens when this mechanism is disturbed? What are the side effects and how does it impact overall health? Welcome to the world of insulin resistance.
Insulin resistance
When cellular needs for glucose have been met (i.e. the amount of carbohydrate the body requires has been fulfilled) insulin receptors on the cell membrane become down regulated whilst GLUT 4 transporter proteins also move away from the membrane, meaning glucose cannot move into the cell. As a result, if glucose and insulin remain chronically high, the cell becomes resistant to the effects of insulin (shown by high glucose levels in the blood plasma).
Most notably, adipose (fat) tissue retains its sensitivity to insulin throughout this progressive condition. This means that whilst muscle tissue will not be able to accept blood glucose, adipose tissue becomes the primary site for glucose storage and leads to a highly charged fat storing environment.
A lack of glucose in the muscle tissue causes low energy and lethargy. As a result, carbohydrates are consumed to increase energy level, which heightens the current physiological state within the blood plasma and surrounding cells. As insulin resistance progresses, it can lead to extreme health and physique problems such as type II diabetes. Simply put; insulin resistance facilitates weight gain.

insulin 2
So how do I improve my insulin sensitivity? Trying to keep things as simple as I can for my clients, we focus on two methods.

Firstly, we focus on carbohydrate management.
Manipulating your carbohydrate intake is a strategy that I have used with a number of my clients to improve their physiques and health. In brief, supplying your body with an abundance of carbohydrates daily, especially high GI carbohydrates particularly common in processed foods, can actually de-sensitise your body to carbohydrates. Like we touched on previously, it does this through insulin sensitivity. Even if a client’s main goal is to increase muscle mass, it is worth implementing periods of lower carbohydrate dieting. Implementing a low carbohydrate diet has been shown to re-sensitise the body to carbohydrates (Journal of American College Nutrition, 2004). Therefore, when you do come back to eating more carbohydrates, your body is more likely to store them as glycogen rather than being stored as adipose tissue.

Even if you have no interest in reducing your carbohydrate intake, it would be beneficial to choose lower GI carbohydrates, such as quinoa, in all your meals. This will decrease your average daily insulin output over time and will aid in maintaining insulin sensitivity. The work of Nate Miyaki (author of Feast Your Fat Away) has proven a useful tool in the practical application of managing your carbohydrates. Since insulin resistance is closely correlated with body fat, he has noted how certain diets work for different body types. He has recommended these approaches:

25% body fat: Low-carbohydrates diets would be the best. Think Alpha Male 3.0, Paleo, Caveman, LaLanne’s “if man made it don’t eat it”, or Poliquin’s “run, fly, swim, green and grows in the ground” approach. Restricting carbohydrates to <0.5/lb of lean body mass would be a ballpark figure to start.

12-25% body fat: Stick with the “earn your carbohydrates” theme. If you’re consistently strength training three to four times per week, you can reintroduce carbohydrates back into your diet. Start slowly, perhaps 0.75-1.0g/lb of lean body mass. However, timing matters: spread intake over periods where insulin sensitivity is at its highest (post-workout and breakfast).

10% body fat: In addition to post-workout nutrition and breakfast, carbohydrates should be a consistent part of the diet. A high protein, moderate-to-high carbohydrate, lower fat, with fat as a by-product of protein sources approach. A recommended target of 1-2 grams of carbohydrates per pound of lean body mass spread relatively evenly over the course of the day would be a good figure to begin with.

Secondly, we focus on resistance training.
There is no lack of evidence that proves exercise improves insulin health. However, certain types of exercise may be more beneficial than others at improving insulin sensitivity. A study by El Ng et al (2011) compared the effects of a resistance training program with an aerobic training program on individuals with prediabetes. Both programs had participants train for three days a week for eight weeks whilst intensity and volume were closely matched. Whilst both groups improved blood pressure, the resistance training group decreased waist circumference by 1.8cm more than the aerobic group.
Additionally, Philips et al (2010) investigated the effects of resistance exercises using multiple sets and repetitions and found a significant decrease in fasting blood glucose level and significant improvement in insulin sensitivity after an 8 week period. Most notably, this training method lead to greater insulin sensitivity for 23 hours post training.

For this reason, all my clients (both male and female) perform high intensity resistance exercises as their main method of training. We focus on compound movements, such as squats, deadlifts, power cleans etc) resting for 1-2 minutes minimum to allow for greater recovery and the ability to perform with a heavier load. For males, this also has the beneficial effect of raising testosterone levels (Grossman & Mathis, 2011).

Just remember this.
Optimising insulin sensitivity is definitely something worth doing. Not only will you look better, you’ll improve your health and longevity as well. Controlling the amount of carbohydrates you consume whilst choosing resistance exercises as a main part of your training will help you begin to improve your insulin sensitivity. Take these actionable steps and start today.


  1. Lose fat, keep muscle | Cooper Fitness - June 19, 2014

    […] 2. Insulin sensitivity Another key issue in preserving muscle mass is insulin sensitivity. The more muscle mass you have, the greater the insulin sensitivity. Not bothered? A larger muscle has more insulin receptors, which makes the muscle more insulin sensitive. In the most basic terms possible, this means that you’ll tend to store more of what you eat in the muscles instead of as body fat. (check this post to find out more information on the role insulin plays within the body /) […]

Leave a Reply