How We Eat Now (Pt. 1)

Welcome to the first installment to “How We Eat Now”, a four-part series looking at the basics of today’s most popular diets. 

 

Part 1: Intermittent Fasting

 
 

what is it?

While intermittent fasting (IF) may be treated like the new kid on the block, it is far from it. Humans have been fasting (intentionally or otherwise) since the beginning of time, and remains an important practice in many cultures today. IF is an umbrella term for different styles of time-restricted feeding (i.e. alternating between fed and fasted states). 

Types of IF

  • Feeding window
    • Eat for a period of time and fast for the rest
      • Example: Eat over 8 hours (12 pm to 8 pm), and fast for the remaining 16 hours
  • Alternate-day fasting
    • Varying periods of eating and fasting/restricting calories
      • Example: Eating over 12 hours and fast for 36 hours, or eat over 24 hours and fast for 24 hours  
  • Eat-stop-eat
    • Severely restrict calories for 24 hours either regularly (e.g. two days per week, this is known as a 5:2), or at random times 
  • Random meal skipping
    • Skip random meals through the week 

Why do it?

When we were hunters and gatherers in the pre-modern eras, food was often scarce. It was not unusual for our predecessors to go from periods of feast to periods of famine. Fasting at regular intervals (a la IF) mimics the feast/famine cycle. When you look at our physiology, it becomes more evident that being in a fasting state promotes the breakdown of fat (lipolysis). 

 
 
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The Body's Natural Fasting Cycle

Although you may not be aware of it, you already have a regular 8-hour fast built into your day… that is, unless, you have a chronic case of the midnight munchies. Between your last meal of the day until the time you break fast, there are many physiological processes that occur to either store or burn fat. 

Immediately after dinner you enter a state known as the “well-fed” state. Several hours after that, your body transitions into the “early fasting” state, and it stays there until you eat a healthy breakfast first thing in the am. 

 

 
 
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1. Well-fed state: 

  • Sugar and protein (broken down into amino acids) enter the bloodstream from the intestines, and dietary lipids enter via the lymphatic system.
  • Beta cells in the pancreas secrete insulin, which stimulates the storage of fuels (i.e. fat and sugar) and protein synthesis.

 

2. Early-fasting state: 

  • As blood glucose levels begin to drop, there is a decrease in secretion of insulin, triggering a rise in glucagon secretion. 
  • Glucagon is secreted by the alpha-cells in the pancreas. 
  • Glucagon signals a starved state and causes the release of glycogen stores. 
  • When there is low blood-sugar, the muscles and liver use fatty acids as energy 

 

3. Re-fed state

  • Fat is processed normally (i.e. stored in adipose tissue)
  • The liver replenishes it’s glycogen supplies with the rising blood-sugar, and processes the extra glucose for fatty acid synthesis 
 
 
 

Benefits of IF

If you love food as much as I do, then the thought of intentional fasting may seem like sacrilege. Depriving yourself of food cannot be a good thing, right? Well, the stars (and scientific literature) seem to point in the opposite direction. There are actually quite a few benefits to fasting including: 

  • Weight loss
  • Improved insulin sensitivity 
  • Decreased blood pressure 
  • Improved neuro-protection
  • Improved blood lipid profile

But is it all sunshine and rainbows?

Not exactly. While research seems to support the inclusion of intermittent fasting to a healthy lifestyle (READ: a lifestyle including healthy eating and exercise), a closer look needs to be taken at the type of studies being done. To date, the majority of studies showing benefit have been done on mice/rodents, so the findings cannot be superimposed on to humans. Moreover, the studies that HAVE been done haven’t been as conclusive (some show that there is a benefit, while others do not). Without a large body of double-blind, RCT studies (randomized controlled trials - the gold standard of scientific research), it is difficult to say with certainty that IF is something that we should all do

So.. what you’re saying is…

Health and human physiology is not black and white. Intermittent fasting may be really beneficial to some people, but not work at all in others. It all depends on your individual circumstances. While I cannot say for certain that IF is the way to go, there is enough evidence to show that reducing overall calorie intake in combination with regular exercise and a healthy, whole foods-rich diet is conducive to good health. 

That being said, if you have poor glycemic control, are underweight, pregnant, under 18, or have a history of disordered eating, do not start this type of eating plan before having a proper consultation with a licensed healthcare practitioner. 

 

Disclaimer: This article is for educational purposes only and is not meant to diagnose, prescribe, or treat. Always consult your primary care physician for advice on your wellness goals.