The Obesity Code Cookbook. Jason Fung

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      THE OBESITY CODE COOKBOOK

      When TO eaT

      The DIeT (What to Eat) addresses the first half of the problem, but

      remember that long-term weight loss is a two-factor process. Two major

      factors maintain our insulin at a high level. The first is the food we

      choose to eat: what we eat and how much of it is fattening. When we

      eat, insulin goes up and our body gets hormonal orders to store body fat.

      But the total insulin effect on the body is not simply determined by how

      high insulin levels get. It also depends critically upon how long those

      insulin levels stay up for. That’s why it’s so important to allow periods

      when insulin levels are allowed to drift downwards. Fasting (When to

      Eat) addresses the second half of the problem. Fasting corrects some of

      the hormonal problems that cause obesity and so helps maintain long-

      term weight loss. Combining the proper diet with intermittent fasting is

      a time-tested weight-maintenance method.

      What does that mean? Suppose you spend $1,000 in one day. That’s

      a fantastic shopping day. If this happens only once a year, that’s accept-

      able. However, if it happens every single day, you will soon be very poor.

      So, the total effect depends not only upon the level but also the duration

      and frequency of the activity. Insulin is no different. The total insu-

      lin effect depends not only upon how high insulin levels get (which

      depends upon the foods we choose to eat), but also upon how persistent

      those high insulin levels are. This depends upon how often you eat,

      which is an entirely different issue than which foods we choose to eat. If

      you are trying to lose weight, an insulin spike once or twice a day is far

      preferable to multiple spikes per day.

      How can we induce our body into a temporary state of very low insu-

      lin levels? Because all foods raise insulin, the only way for us to lower it

      is to completely abstain from eating. The answer we are looking for is, in

      a word, fasting. Fasting refers to any period in which you do not eat. This

      may be several hours (between meals) or several weeks. For weight loss

      and a reversal of type 2 diabetes, I commonly recommend intermittent

      fasts of sixteen to thirty-six hours.

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      introduction

      Fasting is one of the oldest remedies in history, but it is not to be

      confused with starvation, which is a notably unhealthy state. Starvation

      is involuntary abstinence from food; it is neither deliberate nor con-

      trolled. If you have not eaten for a while, and have no idea when you will

      eat again, you are starving. By contrast, fasting is voluntary abstinence

      from food for spiritual, health, or other reasons. You may fast as long as

      you like, but you can always decide to eat again, if you like.

      People often worry that if they don’t eat, they’ll have less energy

      and they won’t be able to concentrate as well, but that’s simply not true.

      Think about the last time you ate a huge meal—for example, at Thanks-

      giving. Did you feel more energetic and mentally alert afterward? Or did

      you feel sleepy and a little dopey? More likely the latter. Eating shunts

      blood to your digestive system to cope with the huge influx of food, leav-

      ing less blood for brain function. Fasting does the opposite, meaning

      there’s more blood for your brain. The human body has adapted to func-

      tion and thrive in the temporary absence of food.

      Glucose and fat are our main sources of energy. When glucose is not

      available, the body adjusts by using fat. Fat is simply our stored food

      energy. That’s what it’s designed for. In times of food scarcity, stored food

      (fat) is naturally released to fuel our bodies. That’s entirely normal. The

      transition from the fed state to the fasted state occurs in several stages:

      1. Feeding: During meals, insulin levels go up, allowing glucose uptake

      by tissues such as the muscles or brain for direct use as energy. Excess

      glucose is stored as glycogen in the liver.

      2. The post-absorptive phase (six to twenty-four hours after fasting

      starts)

      : Insulin levels fall. The breakdown of liver glycogen releases

      glucose for energy. Glycogen stores last for roughly twenty-four hours.

      3. Gluconeogenesis (twenty-four hours to two days): The liver manu-

      factures new glucose from amino acids and glycerol. In people who

      do not have diabetes, glucose levels fall but stay within the normal

      range.

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      THE OBESITY CODE COOKBOOK

      4. Ketosis (one to three days after fasting starts): The storage form of

      fat, triglycerides, is broken into the glycerol backbone and three fatty

      acid chains. Glycerol is used for gluconeogenesis. Fatty acids may

      be used directly for energy by many tissues in the body, but not the

      brain. Ketone bodies, capable of crossing the blood-brain barrier, are

      produced from fatty acids for use by the brain. Ketones can supply up

      to 75 percent of the energy used by the brain.

      5. Protein conservation phase (after five days): High levels of growth

      hormone maintain muscle mass and lean tissues. The energy

      required to maintain basal metabolism is almost entirely produced

      by available free fatty acids and ketones.