Once again, weight loss is at the top of the public health agenda, with a recent Victorian State Government campaign featuring graphic images of “toxic fat”. The rise and rise of obesity in Australia has contributed to exponential increases in health costs which are unsustainable in the long term. Given these dual health and financial burdens, the government is aiming to educate people on the health dangers of being overweight or obese.
As I have written in previous blog articles, achieving and maintaining a healthy weight is not only a high priority for people with chronic health conditions, but for all who wish to live life with vitality! So what are the major contributors to weight gain?
EXCESS SUGAR AND CALORIES
Sugar has been heavily added to our foods over the past decade and is a major contributing factor to the rapid increase of diabetes and obesity in our population. Sugar can be easily over-consumed due to its low satiety value (how full a food makes you feel), which ultimately means an excess consumption of calories. If you sustain a pattern of over-consuming empty calories over time, you will gain weight! So if this has happened to you, what can you do?
My advice to clients wanting to lose weight is simple: consume less sugar and expend more energy. But if it’s a simple equation, then why should you know about GLUT4? What on earth is GLUT4 anyway?
GLUCOSE TRANSPORTER 4 (GLUT4)
Glucose Transporter 4, or GLUT4, is a naturally-occurring protein in your body that can do amazing things with the excess sugar and calories in your body. To expend calories, and in this specific example, sugar, you need three biological processes to happen:
- The sugar needs to be delivered to the muscles through the bloodstream…
- Then it needs to be transported from the bloodstream and into active muscle…
- Where the sugar is metabolised, i.e., used to produce energy.
When you start exercising, your body increases its delivery and use of sugar (in the form of glucose) to the working muscles in order to produce energy and sustain movement. As exercise intensity increases, glucose delivery and metabolism continues to increase. This is where GLUT4 steps in. GLUT4 is a protein that transports sugar into the muscle so that it can be metabolised. When you are not exercising, GLUT4 is only activated by the release of insulin from the pancreas. But what is really interesting is a process known as “exercise-induced glucose transport”: exercise is the only other stimulus that activates GLUT4 and, in turn, enhances the delivery of sugar into muscle cells for metabolism! In plain English, this means that an increased amount of sugar enters your muscles to be used for energy production.
So what does all of this have to do with weight loss?
If I told you that, in order to lose weight, you needed to expend calories (specifically those from sugar), and that GLUT4 is a key protein in that process…would you take a GLUT4 supplement?
I’m sure most of us would. And you can. The supplement is exercise! And the best weight loss strategy is one where you replace sugar, sitting, and physical inactivity in your life with regular exercise.
EXERCISE IMPROVES GLUCOSE TRANSPORT
What sort of exercise will give you the most GLUT4 activity? Resistance training! That is, using and moving loads or weights. Research has found that resistance training improves insulin-mediated glucose transport, and increases GLUT4 activity through muscular contraction (Holten et al., 2004; Dela & Kjaer, 2006; Ivy, 1997). In other words, the stronger and more frequent your muscle contractions, the more GLUT4 is stimulated.
For people with Type 2 Diabetes, this is more important as their muscles are insulin-resistant. That is, insulin does not work as effectively to move sugar into the muscles where it can be metabolised. As a result, high amounts of sugar accumulate in the bloodstream, which leads to weight gain but is also toxic for your organs and nerves.
To optimise the function of GLUT4, we at Inspire Fitness recommend that you undertake resistance training at least 3 days per week for 45–60 min. The exercise program should include whole-body exercises and should become progressively more challenging as your fitness and strength increases over time. Cardiovascular training should also be undertaken on most, if not all, days of the week for a minimum of 30 min.
Written by Rory Scott, Accredited Exercise Physiologist.
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