“Hormones are central to understanding obesity. Everything about human metabolism, including the body set weight, is hormonally regulated. A critical physiological variable such as body fatness is not left up to the vagaries of daily caloric intake and exercise. Instead, hormones precisely and tightly regulate body fat. We don’t consciously control our body weight any more than we control our heart rates, our basal metabolic rates, our body temperatures or our breathing. These are all automatically regulated, and so is our weight.”
- The Obesity Code, Jason Fung, MD 
Everyone knows “that person” who seems to stay skinny no matter what they eat. They probably even complain to you about it. Just admit it, you hate them a little.
I get it. Skinny, fat and everything in between seems to be something determined at birth. You’ve tried a hundred times to lose weight only to fail or to regain it.
Maybe you aren’t overweight, but just struggle to rid stubborn fat in a few places. Either way, this is for you.
Today I am going to teach you why everything you try fails and what you can do to achieve permanent weight loss.
“That skinny person” can be you. Here’s how.
Understanding Weight Loss: Overcoming Myths & False Assumptions
The diet industry is riddled with myths and lies about weight loss. We'll save why that is for another conversation.
Here are the two most common and most misleading doctrines of weight loss.
Myth #1: Eat Less to Lose Weight
The most common belief surrounding weight loss can be summarized by the following equation.
Calories In - Calories Out = Body Fat.
This is completely wrong, yet remains popular because it’s simple and because on the surface it appears to be true.
If you reduce the amount of calories you consume you will lose weight, in the short term. However, over time you will gain the weight back. Because hidden beneath this theory are several false assumptions.
False Assumption #1: Calories in & calories out are independent. The diet industry would have you believe that how many calories you burn (your metabolic rate) stays constant regardless of how many calories you eat.
Actually calories in & calories out are dependent variables.Your metabolic rate rises and falls in lockstep with the amount calories you consume. This is known as the thermic (or thermogenic) effect of food.
The Truth: When you eat more your body burns more calories. When you eat less your body burns less calories.
False Assumption #2: Basal metabolic rate is stable. Basal metabolic rate is the rate at which your body burns calories in order to perform its basic functions.
Most weight loss theories would have you believe that this is constant, leaving exercise as the only variable affecting your energy expenditure.
Your total energy expenditure can vary by as much as 50%, most of which is attributed to basal metabolic rate. It is also affected by the food you eat , non-exercise activity, exercise, post-exercise oxygen consumption, external temperature, and many other variables.
The Truth: Your basal metabolic rate varies greatly and is affected by many factors.
False Assumption #3: A calorie is a calorie. There is a common misunderstanding that all calories have the same effect on your body regardless of their composition (i.e. protein, fat, or carbohydrate).
If that is true then the only important variable for weight loss would be, you guessed it, calories. But it’s not true.
Different foods have measurably different effects on your body. It’s also just completely unreasonable to believe that eating a Butterfinger (my favorite candy bar) will produce the same hormonal and physiological response as eating a pack of Blue Diamond Wasabi & Soy Sauce Almonds (also my fave) - it won’t.
The Truth: Different foods affect your body differently, a calorie is not just a calorie.
Homeostasis: The Real Reason Losing Weight Is So Hard
Homeostasis is the defining characteristic of the human body, of all life really. It is your ability to adapt to change. Your body makes adjustments to externalities in order to minimize effects and to return to its original state. Your body wants to stay the same.
Traditional weight loss works like this: you reduce calories in and begin to lose weight. So your body adapts by slowing your metabolism, and then by releasing hormones that signal hunger.
Trying to lose weight by reducing calories has two effects, you burn less calories and are hungrier.
Your body automatically resists weight loss, it is trying to return to its original state or set weight. This is another powerful reason why “eat less, lose weight” is unsustainable and will fail, because you are fighting your own body!
Stick with me, I'm about to teach you simple methods to overcome your body’s natural resistance to weight loss.
Myth #2: Exercise More to Lose Weight
Since the 1980s, physical activity in North America has significantly increased, yet the obesity rate has risen even more sharply  - indicating that exercise does not prevent weight gain. Let me say that again, as a society we exercise more and are fatter than ever. Hmm.
The Truth: You will not lose weight by exercising more.
Ample research confirms little to no association between activity levels and rates of obesity.
- Increased activity levels have small impact on obesity prevalence in US counties.
- Sedentary behavior is not associated with BMI scores in children.
- Extremely active people burn no more calories per day than sedentary people.
One reason for this is that exercise accounts for an insignificant portion of the total energy (calories) you burn in a day. The total amount of energy you expend (calories you burn) each day depends on multiple variables. 
The largest percentage of energy you expend each day is accounted for by your basal metabolic rate for tasks such as digesting food, breathing, pumping your heart, maintaining body temperature, etc.
We discussed above that basal metabolic rate is heavily dependent on the amount of calories you consume. We must then conclude that diet controls 95% of the calories you burn. You can’t outrun a poor diet.
The Truth: Diet, not exercise, does most of the work in weight loss.
Side note, it has also been proven that increased exercise leads to increased caloric intake. When you exercise you get hungrier and you eat more.
Let me say this before we move on, exercise is important. It’s just not equally important. Diet matters more.
False Theories Lead to Misplaced Blame and Hopelessness
Here’s what we have established so far:
- You won’t permanently lose weight by eating less.
- You won’t lose weight by exercising more.
Leading weight loss theories are failing in mass proportions. But instead of looking for reasons why the theories are failing people, most “experts” prefer to ignorantly blame people for failing the theories.
At some point everyone has believed that it’s your fault you can’t lose weight. You are too lazy. You aren’t actually exercising like you say you are. You don’t have self discipline to stick to your diet. Or you are secretly snacking between meals.
These accusations effectively make you a liar. They make you feel guilty and shameful for failing, as if your inability to lose weight is completely your fault.
It’s not your fault that you struggle to lose weight and keep it off. It is the theory’s fault. We need a better theory.
How Weight Loss Actually Works: The Hormonal Theory
“Obesity (Weight Gain) is not caused by an excess of calories, but instead by a body set weight that is too high because of a hormonal imbalance in the body.”
- The Obesity Code, Jason Fung MD
Your body set weight  is how much your body thinks it should weigh, your natural baseline weight. Your body wants and tries desperately to stay at this weight.
So then effective and permanent weight loss means lowering your body’s set weight.
There are many hormones involved in the digestive and metabolic process, but today we are going to focus on the key regulator of energy, the fat accumulation and storage hormone: insulin.
Insulin: The Fat Storage Hormone
Hormones are molecules that deliver messages to cells in your body. They are signals for your body, or specific parts, to perform certain actions.
When you eat, your blood sugar goes up. Insulin shuttles that blood sugar (glucose) around to different organs and tissues to use for energy.
Any excess glucose is carried to your liver where it is converted into glycogen for later use through a process called glycogenesis.
The liver has limited storage space for glycogen, so once it fills up the additional glucose coming in is converted into fat and stored. This process is known as de novo lipogenesis.
When you eat insulin goes up encouraging sugar and fat storage. But on the other hand, when you fast insulin goes down encouraging glycogen and fat burning.
If your “feasting and fasting” periods are balanced, your weight should be too.
High Insulin Levels Increase Your Body Set Weight
This study placed a group of Type II diabetics on insulin therapy. They received insulin injections gradually increasing in dosage over time while simultaneously lowering calorie intake. Their blood sugar was controlled but the group experienced “progressive weight gain”. Eating less and increasing insulin will make you fat.
The same weight gaining effect of insulin has also been seen in non-diabetic individuals.
If Insulin Makes You Fat, What Raises Insulin?
Our objective for weight loss is to lower insulin levels. One way to do that is to avoid things that raise insulin levels.
Stress Raises Insulin
Cortisol is the stress hormone. Cortisol raises glucose levels, subsequently raising insulin. So high levels of cortisol make you fat.
Cortisol also causes insulin resistance, which increases the level of insulin in your body, again making you fat.
One step towards reducing your weight is eliminating stress from your life. Here are a few methods to do that: mindfulness meditation, yoga, massage therapy, exercise, and limiting exposure to negative relationships (yes, you should ruthlessly cut stressful relationships out of your life).
Refined Carbohydrates and Dietary Sugars Raise Insulin
Carbohydrates and sugars are the primary offenders of weight gain. These foods raise blood sugar and insulin more than any others.
The greatest proponent of the carbohydrate-insulin hypothesis was Dr. Robert Atkins (Atkins Diet). As the low carb method began to grow more and more studies appeared, confirming low-carb as effective for weight loss - further revealing the fattening nature of carbohydrates.
Refined carbohydrates are so fattening because they are sugar. They spike blood glucose and insulin levels and provide zero nutritional value.
High carbohydrate diets slow your metabolism the most. Carbohydrates also don’t trigger the release of satiety hormones - when you eat them you don’t get full, causing you to eat a lot more carbohydrates than you would food containing protein or fat.
Bottom line, processed carbohydrates and sugar are bad. More about this in a minute.
Low Insulin ALONE Is Not Enough to Lower Your Body’s Set Weight
Low carb diets showed much promise for weight loss in the short-term because they keep insulin levels low. However, over time some issues arose.
In a year or two post dieting, low-carb and low-fat dieters regain weight at approximately the same rate. Actually most of the benefits of low-carbing evaporate after a year.
If you’re low-carbing and want benefits that last, you have to stay on your diet forever. But low-carb diets are super restrictive, so keeping with it all the time is hard.
Also, we’re human. No one wants to stick to a diet forever. We have parties, and holidays, and celebrations, and other special occasions (like weekends) to enjoy! And rightfully so.
Indulging shouldn’t blow all the hard work you’ve put in to improve your health.
Most importantly, Low-carb diets lower insulin in comparison to high-carb diets. Because all food raises insulin, some just more than others.
There must be something else missing from our puzzle.
The Missing Component to Permanent Weight Loss: Insulin Resistance
I mentioned previously that hormones are signals to tissues and cells to perform certain actions. Insulin signals cells to accept glucose for energy. When a cell no longer responds to insulin, i.e. it won’t do what insulin is telling it to do, that cell is said to be insulin resistant.
Insulin Resistance is significant and concerning because it creates a self perpetuating cycle of persistently high insulin independent of diet.
High insulin causes resistance, which leads to high insulin, which causes resistance, and so on. You can see how over time this becomes a huge problem.
To lower your body’s set weight you must lower insulin levels and keep them low. To maintain low insulin levels you must eradicate insulin resistance.
Insulin resistance results from high hormone levels and constant stimulus, therefore reversing it is a two step process - a function of two variables: meal composition & meal timing. 
Permanent Weight Loss: A Two Part Equation
Congratulations for making it this far. This post is a doozy, I know. Onward!
Permanent weight loss results from persistently low insulin levels. Lowering insulin is a function of what you eat, and maintaining low insulin levels is a function of when you eat. So now, what you’ve been waiting for.
Part 1: WHAT to Eat to Lose Weight - Lowering Insulin
Here are some rules for lowering insulin levels and losing weight. Quick caveat: Any good weight loss plan should be tailored to the individual. Regardless, these rules will be beneficial for anyone.
Definitely Don’t Eat Sugar
Sugar is the first thing to go in any respectable diet, and for good reason. Sugar is uniquely fattening in that it directly produces insulin resistance and contributes no nutritional qualities. So no more sugar, sorry.
Food manufacturers are sneaky, so read labels. Here are a few ways sugar is disguised: high-fructose corn syrup, sucrose, glucose, fructose, maltose, dextrose, molasses, hydrolyzed starch, any other type of syrup. If you see it, don’t eat it.
Sugar addiction is hard to break, here are a few tips for what to eat instead.
Eat six meals a day to keep your metabolism high… probably the worst health advice ever. Eat three meals per day AT MOST, and don’t snack in between.
Eating between meals keeps your insulin high, which we don’t want. Also most snacks are highly refined foods like bars, cookies, muffins, or anything else that comes wrapped in plastic. Keep it out of sight, or better yet, just don’t buy it.
Your Drinks Are Killing You, Softly
Sweetened drinks gotta go too, which is most: soda, juices, shakes, anything with added sugar. Because the sugar keeps your blood glucose and insulin high.
What should you drink? Water. But if you need some flavor (ahem, caffeine) in your life, I definitely do, drink coffee & tea. There are many different varieties of tea. It can be served hot or cold and is quite beneficial.
Coffee is super good for you too. It is a major source of antioxidants, lowers risk of diabetes, can guard against alzheimer’s, liver cancer, and more. Drink it. If you get jittery, maybe back off a little.
Reduce Consumption of Refined Grains (Carbohydrates)
Cereal is not good for you, despite what the heart healthy labels would have you believe (no, not even cheerios). A good rule of thumb is to avoid all processed foods. That includes: bread, bagels, cookies, cake, donuts, biscuits, tortillas, muffins, crackers, pasta, and noodles.
You can still eat carbs, just eat the good kind. Carbohydrates are found in veggies like: tomatoes, broccoli, carrots, brussels, zucchini, avocados, cucumbers, asparagus, spinach, etc.
When you eat veggies whole you are also consuming fiber. Fiber acts as a buffer and keeps your blood glucose and insulin low.
Okay, we have just cut a lot of things out of your diet. It’s time to talk about what you should be eating. I’ll start with what is most likely your biggest concern . . .
Do Dessert the Right Way
Eat fresh fruit, or a bowl of berries. Top it with whipped cream (full fat). This will allow some sugar in your diet but the fiber and extra substance of the fruit will keep you from overindulging and acts as a buffer against high blood glucose.
Have some dark chocolate, preferably that is over 70% cocoa - it’s good for you. Just remember that I said SOME.
Lastly, you don’t need dessert every day. Make it an occasional treat. It’s a good practice in self discipline and will be much more satisfying and guilt free when you do indulge.
Eat More Fat
Fats are the least likely of the macronutrients (protein, carbs, fats) to stimulate insulin. Insulin makes you fat, so by extension dietary fats are not inherently fattening.
This may seem weird or counterintuitive, because it is completely contradictory to everything you have been told about nutrition your whole life.
Fats can actually be protective because when eaten in conjunction with other foods they lower the insulin response!
There are good fats and bad fats, so be sure to get the right ones.
- Natural oils: olive oil, coconut oil, anything of the like. No vegetable oil.
- Real Butter, not margarine.
- Nuts: almonds, walnuts, cashews, pistachios, etc.
- Peanuts don’t count, they are actually legumes.
- Full fat dairy: whole milk, cream, full fat cheese, and avocados.
- Low fat dairy is heavily processed, unnatural and high in carbohydrates.
Part 2: WHEN to Eat to Lose Weight - Reversing Insulin Resistance
Meal timing is the most important factor for permanent weight loss, because although eating the right food prevents extremely high levels of insulin, all foods increase insulin to some degree.
Because all foods increase blood glucose and insulin, the only way to lower insulin enough to reverse insulin resistance is to abstain from all food. Some people call this fasting.
If you only take one thing away from this article, take this: YOU SHOULD BE FASTING. I'll get to a few ways you can begin doing that in a bit.
Fasting for Healing Throughout History
Fasting is one of the oldest traditions and practices known to man. It has been used in healing for as far back as we have recorded history.
The Greek physician Hippocrates (460 - 370 BC) is considered the “Father of Modern Medicine” and was a staunch advocate of fasting. He wrote, “To eat when you are sick, is to feed your illness.”
The Greek philosophers Plato & Aristotle both fasted for “greater physical and mental efficiency.”
Paracelsus (1493 - 1541) is the Swiss German philosopher and doctor who founded toxicology, the study of adverse effects of chemicals on living organisms. He said, “Fasting is the greatest remedy - the physician within.”
Benjamin Franklin (1706 - 1790) fasted often and wrote, “The best of all medicines is resting and fasting.”
Fasting is also a practice of most major religions. Jesus, Buddha, and Mohammed all fasted.
The Transition Stages of Fasting
Your body normally runs on glucose in your blood from the food you eat. When glucose isn’t available your body has the ability to use fat for energy.
This transition from the fed state to the fasted state occurs in several stages.
- Absorptive State (up to 4 hours into fasting): You eat and your body raises insulin to use the glucose in your blood stream. Extra glucose is stored as glycogen.
- Postabsorptive State (6 to 24 hours into fasting): Glucose in your bloodstream is low so your body begins to break down stored glycogen for energy.
- Gluconeogenesis (24 hours to 2 days into fasting): Glycogen stores have been depleted so your liver begins producing new glucose using amino acids and glycerol to stabilize your blood sugar.
- Ketosis (one to 3 days into fasting): Your body begins breaking down fat to produce a type of energy known as ketone bodies to fuel your brain. This is where the magic happens.
What Happens to Your Body When You Fast: The Hormonal Response
Insulin drops and remains low, which improves insulin sensitivity (reverses insulin resistance). Because insulin sensitivity is improved less insulin is required to get glucose to your cells even when you begin eating again, which lowers your body’s set weight.
Lower body set weight = permanent weight loss.
Fasting increases production of growth hormone by double in a 5 day period, which maintains muscle and bone tissue mass. Fasting will not break down muscle tissue.
You are only at risk of deteriorating muscle if your body fat is below 4%, which most people aren’t.
Fasting increases production of adrenaline (norepinephrine) which raises your metabolic rate. Your metabolism won’t shut down, it speeds up. 
Fasting is Easy, Effective, and Flexible
One primary reason fasting is so effective is because it is intermittent. We talked about homeostasis and how the body wants to return to normal, so any constant will eventually lose it’s effect (ahem, dieting).
Fasting also allows a margin for error, which I refer to as cheat days. Enjoy weddings, birthdays, and other celebrations. Eat cake and indulge, occasionally, then fast again.
It’s also simple. There is nothing difficult to understand. It fits into your schedule and will free up more of your time because there is literally no preparation or thought involved. Just don’t eat.
How to Fast for Beginners
You have nothing to fear from fasting. You already fast every day! From the time you finish dinner until your first meal the next day you are fasting.
All I’m encouraging you to do is extend your time in the fasted state. I will get into different types of fasts in a later post, but for now here are some simple ways to start fasting.
- Skip Breakfast. Breakfast is the most important meal of the day - to skip! Wait to eat your first meal at lunch time. This is known as intermittent fasting and is a very common practice. Not only does it give your body more time with low insulin levels, you will also avoid unhealthy breakfast foods like bars, cereals, muffins, biscuits, etc.
- Fast 1 Day per week. Pick one day per week and don’t eat anything for the whole day. Just drink water. Coffee and tea are acceptable too as long as you don’t add cream or sugar (or artificial sweeteners).
- Try a Fasting Mimicking Diet. Last year a study was performed at USC to see if the effects of fasting could be replicated with extreme calorie restriction. The answer is yes. The reason this is awesome because it is all the benefits of fasting without the burden of it, because you get some (very little, but some) food.
Summary of This Article
- The reason the vast majority of people struggle to lose weight and keep it off is because traditional diets and weight loss plans fight the body’s natural mechanisms. It is a losing battle.
- Weight is not controlled by calories or exercise, it is regulated by hormones in your body. The primary hormone being insulin.
- The amount of insulin in your body determines your body’s set weight, or the weight at which it naturally rests.
- In order to achieve permanent weight loss you must lower your body’s set weight.
- To lower your body’s set weight you must focus on lowering insulin and keeping it low for extended periods of time.
- The best ways to do that is by developing proper eating habits. And by fasting regularly.
I want to thank Jason Fung for so eloquently piecing together the rational and evidence behind the hormonal theory of obesity. His writing has been extremely influential in developing my own understanding of weight management and nutrition.
Everyone should read his book, The Obesity Code: Unlocking the Secrets of Weight Loss.
Also be sure to check out his blog Intensive Dietary Management where he discusses all things nutrition and diet.
 Fung, Jason. The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver, Canada: Greystone Books, 2016; p.68.
 Kalm LM, Semba RD. They starved so that others be better fed: remembering Ancel Keys and the Minnesota Experiment. J Nutr. 2005 Jun 1; 135(6):1347-52
 Physical activity energy expenditure has not declined since the 1980s and matches energy expenditures of wild mammals.
 Fung, Jason. The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver, Canada: Greystone Books, 2016; p. 52.
 Fung, Jason. The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver, Canada: Greystone Books, 2016; p. 61.
 Fung, Jason. The Obesity Code: Unlocking the Secrets of Weight Loss. Vancouver, Canada: Greystone Books, 2016; p. 118.
 Fung - Chapter 20 - p. 244 (reference #19, 20)