The Obesity Code - Book Review

blog diet nutrition obesity Jul 16, 2021

It’s official. Obesity is now an epidemic. We already know that obesity is the root cause of many chronic autoimmune diseases. It makes us more susceptible to ill health. And yet it is one of the most challenging health issues for us to manage in the present day.

According to a report by CBC News in 2014, obesity rates tripled in the period from 1985 to 2011 going from six percent to 18 percent.

TRIPLED. In about one generation!

Toronto nephrologist Dr. Jason Fung wrote three very well researched books which have turned our understanding of obesity, diabetes and cancer on their heads. In his 2016 book ‘The Obesity Code: Unlocking the Secrets of Weight Loss’, Dr. Fung explains that one of the main causes of obesity is an excess of insulin produced by the body. This elevated level of insulin promotes blood sugar storage in cells throughout the body. When our blood sugar (glucose) stores are full, the excess sugar is converted to fat.

Dr. Fung makes a very important point in his writing. He clearly states that there is a difference between being fat and being obese.”Obesity is the state of being fat to the point of having detrimental health consequences.” 

According to Dr. Fung, we already know what causes obesity

  1. Insulin resistance
  2. Chronically elevated cortisol 
  3. Sleep deprivation 
  4. Genetics 

Simple, yes? No.

Each of us is unique, so how we maintain or even lose weight is also unique. For some of us this means avoiding excessive refined grains. For others it’s our need to sleep well each night. Still others need to be careful about meal timing. And who wouldn’t feel even better with some meditation, massage therapy and great sleep/wake routines?

Think about it - lowering our sugar intake will not necessarily improve our sleep. And sleeping really well isn’t going to be helpful if we are consuming too much sugar. We need to pull all of these areas together to avoid the health risks that come with obesity.

Here’s how the four factors that cause obesity are connected:

1. Check those insulin levels

If we have consistently high levels of glucose, our inability to get this glucose into our cells with our current levels of insulin will cause our insulin levels to rise even higher to try to help. Interestingly, research tells us that one of the best ways to bring insulin levels back down out of the stratosphere is by fasting. Researchers were talking about this strategy way back in the early 1970’s!

Fasting could be as simple as having no snacks in between our two to three meals each day and/or by not eating after dinner until the following morning when we enjoy a late-ish breakfast. That’s it.

2. Watch for chronically elevated levels of cortisol

By keeping our insulin levels in check every day we are also able to manage our cortisol levels. Cortisol is a glucocorticoid hormone secreted from the adrenal cortex when we are under stress. 

Interestingly, cortisol actually enhances the amount of glucose available to the body to use as a source of fuel. Again, studies published in the early 1970’s showed this to be true. Cortisol will raise insulin levels when it is present in our bodies over the long term because there will be more glucose that needs to be stored in our cells.

For many of us, our increasingly busy, COVID and Zoom focused lives means that stress has become a chronic situation. Never mind trying to keep cortisol at normal levels - our cortisol levels now just keep rising! 

To bring cortisol levels back to earth, we need to engage in activities that will reduce the tension we feel in our minds and our bodies. These kinds of activities might include mindfulness meditation, enjoying a daily breathing practice, doing yoga nidra, spending time in nature, relaxing with a favourite Netflix show, spending time with friends, curling up for a nap, sipping a cup of tea with a great book … you get the idea.

We want cortisol to cycle during the day and night as part of our natural circadian rhythm. We begin to have problems when the rise and fall of cortisol in our bodies doesn’t happen and cortisol levels remain elevated. One of the best ways to bring cortisol levels down is to improve the length and the quality of our sleep.

3. Get high quality restful sleep every night

Getting enough good quality sleep is the third way of helping our bodies shed excess pounds. If we are deprived of restful sleep AND we are under stress, cortisol levels will rise. 

Did you know? Losing sleep for just one night will increase cortisol levels by more than 100 percent!

When we sleep, our bodies and minds get a chance to ‘reset’ for the following day. Our organs, including our brains, are rejuvenated, cells are replaced, glucose returns to normal levels and, seven to nine hours later - we get to start fresh!

4. Blame your grandparents? Wait, what?!

Dr. Fung’s book talks about the curious effect of genetics on obesity rates. And, no, it’s not as easy as saying ‘I come from a family of large people!’. By some estimates, 40 to 70 percent of the variation in obesity-related traits in humans is heritable.  Isn’t that incredible?

Now this doesn’t mean if our parents or grandparents were heavy that we will be too. It means that nature has a real influence here and we must be careful to adopt balanced nutritional and physical habits to stay healthy. If heredity can be shown to contribute to 40 to 70 percent of our body composition, this also means that on the flip side, 30 to 60 percent is well within our own control.

Give yourself a bit of space and grace the next time you have a less than positive thought about your body.

Take some time to consider what science tells us about obesity. Plan small steps every day in each of the above areas to help keep your body running effectively. Think about these variables the next time you are working with a client who is concerned about their weight.

Work on small steps to avoid snacks, fast after dinner, give yourself the best opportunity for great sleep each night and have a bit of compassion for the body your grandparents gave you!

Interested in learning more about nutrition counselling as a healthcare professional? Join us on July 24 and 25 for ‘Nutrition Counselling for Kinesiologists’. We’re doing a deep dive into how to talk about food with our clients. We’ll show you how to stay within our scope of practice and we’ll talk about the core competencies that define our professional practice around nutrition. 

Not a kinesiologist? You are more than welcome to join us too! We’ll be discussing a huge range of simple to digest (sorry, couldn’t resist that one) nutritional habits that you can use at home and possibly recommend to your clients as well. Get all the info right here.


  1. CBC News (internet). 2014, March 3. Canada’s obesity rates triple in less than 30 years. Available from: Accessed July 15, 2021
  2. Merriment TJ, Tyson JE. Stabilization of plasma glucose during fasting: normal variation in two separate studies. N Engl J Med. 1974 Dec 12; 291(24):1275-8.
  3. Owen OE, Cahill GF Jr. Metabolic effects of exogenous glucocorticoids in fasted man. J Clin Invest. 1973 Oct; 52(10):2596-600.
  4. Cappuccio FP et al. Meta-analysis of short term sleep deprivation on cognition and stress hormones. J Clin Neurol, 2012 June; 8(2):146-50.
  5. Joo EY eg al. Adverse effects of 24 hours of sleep deprivation on cognition and stress hormones. J Clin Neurol. 2012 Jun; 8(2):146-50.
  6. Comuzzie, AG and Allison, D, The Search for Human Obesity Genes. Science, May 1998, May 29. Vol. 280, Issue 5368, pp. 1374-1377 DOI: 10.1126/science.280.5368.1374.

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