Review of Dr. Fung’s Obesity Code

What is the obesity code?

The Obesity Code is written by Dr. Jason Fung, a Canadian Nephrologist and expert in intermittent fasting and low-carb diets.  The book unpacks why our preconceptions about what drives obesity are wrong, why this happened, what drives obesity and proposed solutions to this problem.  Dr. Fung argues that obesity is a hormonal disorder of too much insulin.  When insulin runs too high for too long, it will create insulin resistance and obesity.  He argues that obesity can be cured by balancing these hormones through changing what and when we eat.  For this summary, I will break down the main points of Dr. Fung’s book.  

Why should we not focus on calories as a strategy for combating obesity?

A calorie is a unit of food energy used by the body for multiple functions such as breathing, building new muscle and bone. We intake this caloric energy  from food.  We expel this calorie energy through metabolic functions such as breathing, building new muscle/bone and storing fat.   We assume that obesity happens when we take in too much of this caloric energy and do not expel enough.  

Dr. Fung argues that calories are a proximal cause to obesity and not the ultimate cause.  The proximal cause is the factor that is immediately responsible for the problem.  The ultimate cause is the factor that is responsible for the chain of events that eventually lead to the problem.

Think of the ultimate cause as the root cause of the problem.  When thinking of effective strategies to solve the problem, focusing on the proximal cause is NOT as effective as focusing on the ultimate cause.  We want to get to the root of the problem.  

 Dr. Fung uses alcoholism to further explain why focusing on fixing the proximate cause is not as effective as focusing on the root ultimate cause.  

 The proximal cause of alcoholism is drinking too much alcohol.  

The solution to the proximal cause (the closest factor to the problem) is to reduce alcohol intake.  This solution is clearly not an effective strategy for combating alcoholism because taking away alcohol from an alcoholic does NOT address the underlying problem.  The underlying problem is, why is the alcoholic drinking so much in the first place? We need to dive deeper, past the proximal cause and into the ultimate cause of why the alcoholic is drinking so much.  Some ultimate causes for alcoholism may include: 

• The addictive nature of alcohol
• Family History
• Excessive stress
• Addictive personality.

Potential strategies for addressing these ultimate causes may include counseling, education, group meetings.  As you can see, these strategies have the potential to be much more effective than simply taking away alcohol from an alcoholic.  

This way of thinking can be translated to obesity as well.  Instead of focusing on reducing the calories of an obese individual (proximal cause), we need to dive deeper into the factor that is driving obesity (ultimate cause).  Dr. Fung argues that the driving factor behind obesity is a hormonal imbalance with high insulin being the central feature.  

We incorrectly assume that calories in and calories out are completely independent factors.  The more calories we reduce, the more weight we loose.  However, calories in and out are completely dependent!  When we reduce food calorie intake, we reduce our calorie expenditure.  This is because when we reduce the amount of food we put into our body, our metabolism slows down so that we don’t burn through all our supply.  Basically our body is used to a certain amount of food energy coming in.  That food energy is used for a variety of things other than fat accumulation including: 

• heat production
• new protein production
• new muscle production
• cognition
• increased heart rate
• detoxification
• digestion
• breathing
• fat storage

When we reduce that usual energy intake, our body slows down or shuts off one or more of these systems. Why would the body do this?  Because shutting down different systems will ensure you will survive.  When the body doesn’t receive the adequate caloric energy it needs to fun all of our metabolic systems, it will allocate the energy to systems it deems more valuable and shut off the systems it deems as less prudent in that moment.  

In addition to a lower metabolism, when we simply reduce the amount of calories we put into our bodies we become more hungry.  Our hunger hormones tell us to eat more food because the body is used to operating at a certain caloric level.  When we simply reduce the food we consume, our body produces more hunger hormones and less satiety hormones.  Our body wants to gain that weight right back. 

Hormones NOT calories drive obesity

We do not consciously decide when to put food calories in our body.  Hormones are guiding our decision as to whether or not we eat food.  We eat when our hormones tell us we are hungry and we don’t eat when our hormones tell us we are full.  Our hormones also dictate whether or not food energy should be stored as fat, or if it should be used for other functions.  

A calorie of olive oil will cause a different hormonal response than a calorie of sugar.  A calorie of sugar will increase blood sugar and provoke an insulin response.  A calorie of olive oil will not cause an increase in blood sugar and will not provoke an insulin response. Insulin is the hormone in our body that tells our cells to store glucose as fat.  Chronically elevated levels of insulin will result in insulin resistance and fat gain.

Fat accumulation is an issue of improper energy distribution.  Our hormones are telling our body to store food energy (calories) as fat.  As previously stated, olive oil and sugar will be utilized in different ways by the body due to the fact that these different foods trigger different metabolic responses (the sugar will trigger insulin while the olive oil will not).  Therefore a more effective strategy in combating obesity is to focus on reducing foods that trigger spikes in insulin.  

What about exercise/calories out?

We incorrectly assume that all calories expended are through movement and exercise.  That is INCORRECT.  95% of the food calories that we consume are utilized for basal metabolism (breathing, body temperature, heart pumping, brain function etc.).  Less than 5% of the calories you expend are through exercise.  When we workout more, we tend to consume more.  Dr. Fung gives an example of one study conducted by The Harvard School of Public Health on 538 children.  For every extra hour of exercise these kids did, the kids consumed an extra 282 calories.  As previously stated, caloric intake and expenditure are intimately related.  Increase calories expended and you will increase calories taken in (eating).  Decrease calories expended (less working out) and you will decrease calories taken in (eating).  

Our body is a thermostat 

As we can see, our body wants to stay at a certain body weight.  It wants to stay in homeostasis.  More food in, more food is burned.  Less food in, less food is burned. So how do we gain weight if our body is constantly trying to bring us back to our usual weight?  Dr. Fung argues that the reason why we gain weight gain is because this usual body set weight slowly increases through time.  This body set weight increases through an imbalance of hormones, specially chronically high insulin.  Dr. Fung argues that the best way to combat obesity is to lower insulin secretion so that we can bring our body set weight down.  Dr. Fung argues that we can lower insulin through decreasing the consumption of insulinogenic foods, decreasing stress, and eating less often.  

Insulinogenic foods 

In order to lower the amount of insulin released in our body, Dr. Fung argues that we should make the following adjustments to our diet:  

• Decrease foods high in sugar- soda, candy 
• Reduce consumption of refined grains- pasta, bread
• Consume a moderate protein, high fat diet 
• Don’t eat all the time.  Eat 2-3 large meals a day with no snacks.  
• Eat nutrient dense foods

My thoughts

I very much enjoyed reading Dr. Fung’s book.  By shifting the focus from calories to hormones, we are better able to understand why different dietary approaches have proven to be effective.  Obesity is a multifactorial disease.  Many different factors contribute to the hormonal imbalance of chronically high insulin levels that drive obesity.  High sugar and carb intake, high stress, reduced fiber intake and frequent eating are all factors that chronically raise insulin.  The  hormonal theory of obesity can help us better tailor dietary intervention to fit the needs of the individual.  Here are two examples of how this theory can be applied in practice: 

Example 1: Person A consumes a low carb, moderate protein, high fat, high fiber diet.  Person A consumes food 6 times a day, fasting for only 8 hours a day (during sleep).   A potential weight loss strategy would be to advice this person to reduce the frequency at which they eat.  This is an effective weight loss strategy because eating frequency is one of the many factors that raises insulin.  

Example 2:  Person B is also consuming a low carb, moderate protein, high fiber diet.  Person B consumes food 3 times a day.  Person B also consumes artificial sweeteners and is chronically stressed.  A potential weight loss strategy would be to advice this person to find ways to reduce stress (via meditation, exercise) and reduce the consumption of artificial sweeteners.  Again, this is an effective weight loss strategy because artificial sweetener consumption and chronic stress are two of many factors that raise insulin.  

As you can see in both examples, its all about context.  It is not one specific food that drives obesity, its the chronically high insulin that drives obesity.  High consumption of refined grains, sugars, frequent eating, frequent stress are all examples of behaviors that keep our insulin high.  Chronically high insulin is essentially screaming the following things to our body:  

• Store more fat!  
  • Insulin tells our fat cells to store more fat
• You are not full!
  • High insulin= high leptin (fullness hormone).  When leptin is chronically high, we eventually become resistant to it.  Therefore, never feeling full.  
• Do not burn that stored fat!
  • We can not access the fat stored in our bodies if our insulin is constantly elevated

It is our job as nutrition professionals to explain to our clients why certain foods and behaviors drive obesity instead of simply stating “Eat less, move more”!  Not only is this motto not effective, it basically screams “YOU are the own to blame for your weight problem.”  I do not think people understand that certain foods and behaviors trigger fat storage and hunger.  Its time for us nutritionists to change the narrative on how we approach dietary advice.  Lets focus on advocating for the foods that will nourish us and condemn the foods that drive fat storage and make us feel hungry.