“Traditionally, obesity has been seen as a result of how people process calories, that is, that a person’s weight could be predicted by a simple equation:
Calories in – calories out = body fat.” – Dr Jason Fung
THE OBESITY CODE
Every page of this book brings to light why we have the Obesity crisis we do in today’s world.
Dr Jason Fung focuses on obesity and works with patients suffering from this disease.
In this book he explains in easy to read format how we have become so unhealthy and how the body is being abused in so many ways living a life of fast foods, overeating and just not respecting our bodies to do what they were made to do.
This book review is very lengthy, because there was so much content – so I have broken it down into four parts, so you can read a bit at a time.
This should allow the content to sink in.
Again if you like this review, please go and buy the book – it’s one you’ll always reread over at different times of your life.
This key equation perpetrates what is called the calorie deception.
It is dangerous precisely because it appears so simple and intuitive. But what you need to understand is that many false assumptions are built-in.
Assumption 1: Calories in and calories out are independent of each other.
-This assumption is a crucial mistake.
-Experiments and experience have proven this assumption false.
-Caloric intake and expenditure are intimately dependent variables.
-Decreasing calories in triggers a decrease in calories out.
-A 30% reduction in calorie intake results in a 30% decrease in calorie expenditure.
-The end result is minimal weight loss.
Assumption 2: Basal metabolic rate is stable.
-We obsess about caloric intake with barely a thought for caloric expenditure, except for exercise.
-Measuring caloric intake is simple, but measuring the body’s total energy expenditure is complicated.
Therefore, the simple but completely huge assumption is made that energy expenditure remains constant except for exercise.
-Total energy expenditure is the sum of basal metabolic rate, thermogenic effect of food, non exercise activity thermogenesis, excess post-exercise oxygen consumption and exercise.
-The total energy expenditure can go up or down by as much as 50% depending upon the calorie intake as well as other factors.
Assumption 3: We exert conscious control over calories in.
-Eating is a deliberate act, so we assume that eating is a conscious decision and that hunger plays only a minor role in it.
-Numerous overlapping hormonal systems influence the decision of when to eat and when to stop.
-We can consciously decide to eat in a response to hunger signals that are largely hormonally mediated.
-We consciously stop eating when the body send signals of satiety (fullness) that are largely hormonally mediated.
For example, the smell of frying foods makes you hungry at lunch time. However, if you have just finished a large buffet, those same smells may make you slightly queasy. The smells are the same.
-The decision to eat or not is principally hormonal.
–Our bodies guide us to eat or not.
-Body fat regulation is under automatic control, like breathing. We do not remind ourselves to breathe, like we do not remind our hearts to beat.
-The only way to achieve such control is to have homeostatic mechanisms.
-Since hormones control both calories in and calories out, obesity is a hormonal, not caloric, disorder.
Assumption 4: fat stores are essentially unregulated.
-Every single system in the body is regulated.
-Growth in height is regulated by growth hormone.
-Blood sugars are regulated by the hormones insulin and glucagon, among others.
-Sexual menstruation is regulated by testosterone and oestrogen.
-Body temperature is regulated by thyroid stimulating hormone and free thyroxine.
The list is endless.
-New hormonal pathways in the regulation of fat growth are being discovered all the time.
-Leptin is the best known hormone regulating fat growth, and adipose triglyceride lipase may all play important roles.
-If hormones regulate fat growth, than obesity is a hormonal, not a caloric disorder.
Assumption 5: A Calorie is a Calorie.
This assumption is the most dangerous of all.
–A calorie is a calorie implies that the only important variable in weight gain is the total caloric intake, and thus, all foods can be reduced to their caloric energy.
But does a calorie of of olive oil cause the same metabolic response as a calorie of sugar?
The answer is, obviously, no.
These two foods have many easily measurable differences.
Sugar will increase the blood glucose level and provoke an insulin response from the pancreas. Olive oil will not.
When olive oil is absorbed by the small intestine and transported to the liver, there is no significant increase in blood glucose or insulin.
The two different foods evoke vastly different metabolic and hormonal responses.
Example of a calorie restricted diet:
Assume that prior to dieting, a woman eats and burns 2000 calories per day.
Following doctors orders, she adopted calorie-restricted, portion controlled, low fat, reducing her intake by 500 calories per day.
Quickly, her total energy expenditure also dropped by 500 calories per day, if not a little more.
She feels lousy, tired, cold, hungry, irritable and depressed, but sticks with it, thinking that things must eventually improve. Initially, she loses weight, but as her bodies calorie expenditure decreases to match her lowered intake, her weight plateaus.
Her dietary compliance is good, but one year later, things have not improved. Her weight slowly creeps back up, even though she eats the same number of calories.
Tired of feeling so lousy, she abandons the failed diet and resumes eating 2000 calories per day.
Since her metabolism has slowed to an output of only 1500 calories per day, all her weight comes rushing back – as fat.
Those around her silently accused her of lacking willpower.
Sound familiar?
But her weight regain is not her failure. Instead, it’s to be expected.
The exercise myth:
In a Women’s health study done about 40000 women were divided into three groups representing high (more than one hour per day), medium and low levels of weekly exercise.
Over the next 10 years, the intense exercise group was no extra weight.
Furthermore, the study noted, no change in body composition was observed, meaning that muscle was not replacing fat.
We just eat more following a vigorous workout.
A study done by Harvard School of Public Health Found that although physical activity is thought of as an energy deficient activity, our estimates do not support this hypothesis.
-For every extra hour of exercise, the kids ate an extra 292 calories.
-Caloric intake and expenditure are intimately related: increasing one will cause an increase in the other. This is the biological principle of Homer stasis.
-The body tries to maintain a stable state.
-“Reducing calories in reduces calories out. Increasing calories out increases calories in”.
The problem in obesity is that the set point is too high.
Example: Suppose our body weight is 90kg.
By restricting calories, we will briefly lose weight say down to 81 kg.
If the body set weight stays at 90 kilos, the body will try to regain the lost weight by stimulating appetite.
Ghrelin is increased, and the satiety hormones (leptin) are suppressed.
-At the same time, the body will decrease its total energy expenditure.
-Metabolism begins shutting down.
-Body temperature drops, heart rate drops, blood pressure drops and heart volume decreases, all in a desperate effort to conserve energy.
–We feel hungry, cold and tired a scenario familiar to dieters.
So what do you do…….you eat comforting foods again……
A new hope:
Insulin is a key regulator of energy metabolism, and it is one of the fundamental hormones that promotes fat accumulation and storage.
Insulin facilitates the uptake of glucose into cells for energy.
Without sufficient insulin, glucose builds up in the bloodstream.
Type 1 diabetes results from autoimmune destruction of the insulin-producing cells in the pancreas, which results in extremely low levels of insulin.
At meal times, ingested carbohydrate leads to more glucose being available than needed.
Insulin helps move this flood of glucose out of the bloodstream into storage for later use.
We store this glucose by turning it into glycogen in the liver- a process is called glycogenesis.
(Genesis means ‘the creation of’, so this term means the creation of glycogen.)
Glucose molecules are strung together in long chains to form glycogen.
How it works:
-Insulin is the main stimulus of glycogenesis.
-We can convert glucose to glycogen and back again quite easily.
-But the liver has only limited storage space for glycogen.
-Once full excess carbohydrates will be turned into fat
– a process called de novo lipogenesis.
(De novo means ‘form new’).
Lipogenesis means ‘making new fat’. De Novo lipogenesis means ‘to make new fat’.
-Several hours after a meal, blood sugars and insulin levels start to drop.
-Less glucose is available for use by the muscles, the brain and other organs.
-The liver starts to break down glycogen into glucose to release it into general circulation for energy – the glycogen-storage process in reverse.
-This happens most nights, assuming you don’t eat at night.
– Glycogen is easily available, but in limited supply.
During a short-term fast (fast mean that you don’t eat), your body has enough glycogen available to function.
During a prolonged fast, your body can make new glucose from its fat stores – a process called gluconeogenesis (the ‘making of new sugar’).
Fat is burned to release energy, which is then sent out to the body – the fat-storage process in reverse.
Insulin is a storage hormone.
The process:
-Ample intake of food leads to insulin release.
–Insulin then turns on storage of sugar and fat.
When there is no intake of food, insulin levels fall, and burning of sugar and fat is turned on.
-This process happens everyday.
-Normally, this well-designed, balanced system keeps itself in check.
-We eat, insulin goes up, and we store energy as glycogen and fat.
-We fast, insulin goes down and we use our stored energy.
As long as our feeding and fasting periods are balanced, this system also remains balanced. If we eat breakfast at 7 a.m. and finished eating dinner at 7 p.m., the 12 hour of feeding balances the 12 hours of fasting.
If you continually refill your glycogen stores, you will never need to use your fat stores for energy.
What happens to the excess fat that is produced through de novo lipogenesis?
This newly synthesized fat can be stored as visceral fat (around organs), as subcutaneous fat (underneath the skin) or in the liver.
Part one wrap up:
If you understand that obesity is more than calories, it’s about how your body regulates calories and the role that the hormones play in your body.
Like anything if you know the work that needs to go into something, you look at it differently, and you realise there are ways to go about fixing it.
Dr Jason Fung is an expert on fasting to help those suffering with obesity.
Part two of this review is about how the hormones play a part in all of this – in more detail.
I hope this all made sense…
