Dr. Jason Fung: Fasting as a Therapeutic Option for Weight Loss

Maintaining weight

Dr. Jason Fung is a nephrologist and expert in the use of intermittent fasting and low carbohydrate diets for the treatment of Type 2 diabetes. I’ve listened to over half a dozen of his webcasts and have always been impressed by his professionalism, as well as his evidence-based non-drug approach to treating diabetes. This presentation, delivered at the CrossFit Health Conference in 2018, shares how he has shifted his medical practices with alternative treatment methods as the traditional medical recommendation of drugs and dialysis did not produce the desired outcomes for his patients. His presentation objectives included:

  1. Understanding why long-term weight loss is so difficult;
  2. Introducing the concept of therapeutic fasting; and
  3. Highlighting some myths and misunderstandings associated with the fasting process.
  • The modern eating pattern as Dr. Fung categorized it emerged in 1977 with the development of the Dietary Guidelines for Americans (the US Food Pyramid). This changed the eating frequency from three meals a day to eating six or more times a day, increasing the median eating period to 14 hours and 45 minutes. In that example, I would start eating at 8am and not finish until 10:45 pm (which is after I’m in bed!) This frequent eating keeps insulin levels high all the time and over long durations, insulin will tell the body to store food energy as fat. Not coincidentally, the incidence of obesity and Type 2 diabetes have reached epidemic proportions and unfortunately, most of the treatments have been drug interventions. 
  • The common approach of ‘eat less, move more’ has not shown to have a long-term success rate according to a new study in The New England Journal of Medicine. The first problem is slowing metabolism – if you cut calories, metabolic rate also drops. The second problem is hunger – ghrelin is the hunger hormone that will tell the body to constantly eat to make up for the decrease in calories.
  • Intermittent fasting, on the other hand, allows insulin levels to drop, which puts us in burning mode rather than storing mode. Simply put, when insulin goes up, you store fat; when insulin goes down, you burn fat.
  • With fasting, ghrelin spikes initially but it goes back to baseline after the period has passed. The body will then take the food energy needed from your body fat. For multiple-day fasts, for instance, ghrelin goes up and down but the hunger disappears over time and then ghrelin actually dips to an even lower level, further curbing hunger.  
  • Studies have also shown that women have a much bigger spike in ghrelin but over time, they also reap more weight loss benefit from fasting.
  • In order to lose weight, you need to control the metabolic rate and control hunger. With fasting, your hunger hormone is actually lowered and metabolism stays stable. With chronic calorie restriction and frequent eating, your hunger hormone will increase and metabolism will decrease.
  • Several studies in the Obesity journal showed that you will not burn muscle from fasting but in fact, lean mass is maintained. Your body is intelligent and knows to burn body fat in a fasted state first – it doesn’t burn protein first.
  • Fasting is less about the type of diet – of course, eating well matters. Stay away from foods that circumvent the satiety mechanism like refined grains, sugars and processed junk. If you stick to eat whole foods within the time period, your body will tell you when you’ve become satiated. You don’t need to count calories – listen to your body. 
  • There is not a large amount of data yet on fasting and brain function but it is shown to improve cognitive function. In the bestselling book ‘Unbroken’, the author writes about the prisoners of war who have astonishing mental clarity due to starvation (i.e., reading a book for memory, learning a new language in three weeks).
  • This mental clarity is one of the reasons why intermittent fasting has taken off in Silicon Valley. In the hyper-competitive world of start-ups, the players in the business are all fasting to get an edge. Fasting heightens the senses and you feel better and sharper as it increases noradrenaline and sympathetic tone.
  • More studies need to be conducted on how fasting can prevent Alzheimer’s – the theory is that fasting initiates autophagy of the protein plaques that clogs the Alzheimer brain and also improves mitochondrial health through mitochondrial biogenesis and turnover.
  • One of the questions from the audience was around the benefit of carb loading, restriction (carb cycling) – Fung wasn’t sure that it worked but his guidance was to focus on not stimulating insulin and to not worry about counting the macro nutrients. 
  • Fung explains that diabetes is a nutritional disease but no one is promoting it because there is no money in it.  So in his treatment of patients, he is giving you the power to take back your own health, because “you’re not gonna get it from anywhere else”. 

You can check out his full presentation on YouTube:

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