Why Intermittent Fasting Works with Dr Jason Fung #285
Dr. Jason Fung, a kidney specialist and intermittent fasting expert, discusses how constant eating and refined foods elevate insulin, leading to weight gain and health issues. He advocates for scheduled eating, whole foods, and intermittent fasting to optimize health.
Deep Dive Analysis
16 Topic Outline
Modern Eating Habits and the Problem with Constant Snacking
Common Mistakes and Misconceptions in Intermittent Fasting
The Fed State vs. Fasted State and Calorie Storage
Hormones Over Calories: The Role of Insulin in Health
Misinterpreting the Energy Balance Equation for Weight Loss
Why Calorie Counting Often Fails for Weight Loss
Food Choices to Minimize Insulin Spikes
The Impact of Sugar (Fructose) vs. Starchy Carbs
The Role of Monotony and Variety in Eating Habits
Food Order and Acidic Foods to Reduce Glucose/Insulin Response
Practical Steps for Starting Intermittent Fasting
Physiological Benefits of Fasting Beyond Weight Loss
Fasting and Medications: Important Considerations for Diabetics
Addressing Myths: Fasting for Women and Eating Disorders
Optimal HbA1c Levels and Health Safeguarding
Core Principles for Better Health and Lower Insulin
7 Key Concepts
Fed State
This is the state your body is in when you are eating, characterized by high insulin levels. In this state, your body is signaled to store incoming calories, primarily as body fat, for future use.
Fasted State
This is the state your body enters when you are not eating, characterized by low insulin levels. In this state, your body is signaled to draw energy from its stored calories, such as body fat, to fuel its functions.
Hyperinsulinemia / Insulin Resistance
These are two sides of the same coin, referring to chronically elevated insulin levels in the blood. This state is problematic because it constantly signals the body to store calories, contributing to conditions like heart disease, type 2 diabetes, kidney disease, nerve problems, amputations, and cancer.
Energy Balance Equation Misinterpretation
While the equation (body fat = calories in - calories out) is always true, it's often misinterpreted to mean that simply eating fewer calories guarantees body fat loss. In reality, reducing calorie intake can also lead to a decrease in 'calories out' (metabolic rate), meaning body fat may remain unchanged or even rebound.
Glycemic Index
This index measures how much a carbohydrate-containing food tends to spike insulin and glucose levels. Unprocessed carbohydrates generally cause a much lower spike compared to highly refined or processed foods, even if they contain similar amounts of carbohydrates.
Autophagy
This is a natural process that occurs during fasting where the body breaks down and recycles old, unnecessary, or damaged cellular components and proteins. It's a cleaning-out process that can lead to benefits like skin tightening, rather than just muscle loss.
Amylopectin C
A type of carbohydrate found in foods like beans, which is harder to digest compared to other forms of amylopectin. This slower digestion leads to much lower blood glucose and insulin levels, making these carbohydrates less likely to contribute to weight gain.
8 Questions Answered
Constant eating keeps the body in a 'fed state' with high insulin levels, signaling continuous calorie storage and preventing the body from accessing its fat stores for energy. This modern habit, unlike historical eating patterns, contributes to weight gain and various health problems.
Focusing solely on calories in ignores the body's ability to reduce 'calories out' (metabolic rate) when calorie intake is restricted. This means that eating fewer calories doesn't guarantee fat loss, as the body can adapt by burning less energy, leading to frustration and diet failure.
Chronically elevated insulin (hyperinsulinemia or insulin resistance) impacts a huge number of conditions beyond diabetes, including heart disease, kidney disease, nerve problems, amputations, and cancer. Maintaining balanced insulin levels is crucial for optimal health, energy, and disease prevention.
Foods with the same calorie count can have vastly different hormonal effects. For example, white bread causes a high insulin spike, signaling immediate calorie storage, while eggs have little insulin effect, making energy available for use and promoting satiety. It's the hormonal response, not just calories, that dictates what the body does with the energy.
Eating protein and fat first, then waiting a short period before consuming carbohydrates, can significantly reduce the insulin and glucose spike by about 50% compared to eating carbs first. This strategy helps the body store less energy and keeps you fuller for longer.
A common myth is that fasting burns muscle. While there is a period of protein breakdown (gluconeogenesis) during fasting, it primarily involves breaking down excess protein from skin or connective tissue, not muscle, especially if muscles are being used. The body is designed to use stored fat for energy before muscle.
Intermittent fasting is generally safe and effective for women, though they may respond differently than men, often with slower and more stable weight loss. While sex hormones play a role in fat distribution, there's no inherent danger to women fasting, and results depend on individual physiology and diet quality.
While eating disorders are serious, available research suggests that fasting does not necessarily trigger or worsen anorexia or bulimia. However, careful consideration of individual circumstances is crucial; fasting is a tool that must be used skillfully and is not appropriate for individuals who are underweight or have active eating disorders.
14 Actionable Insights
1. Prioritize Whole, Unprocessed Foods
Focus on eating whole, unprocessed foods, regardless of their macronutrient content, as this is considered the most important dietary principle for health. This approach helps avoid the negative effects of highly processed items.
2. Reduce Sugar Intake
Minimize your consumption of sugar, especially fructose, as it is metabolized differently by the liver, leading to fatty liver, insulin resistance, and is more obesogenic than glucose.
3. Eliminate Refined Carbohydrates
Cut out refined carbohydrates from your diet, as they cause significantly higher insulin spikes compared to unprocessed carbohydrates, contributing to health issues.
4. Stop Constant Snacking
Cease frequent snacking throughout the day, as constant eating prevents your body from accessing and burning stored fat, which is crucial for weight loss and overall health.
5. Schedule Your Eating Times
Deliberately schedule specific times for your meals and only eat during those planned windows, making ’not eating’ your default state to prevent unscheduled and often unhealthy food consumption.
6. Begin Intermittent Fasting (14-16 Hours)
Start intermittent fasting by establishing an 8-10 hour eating window (e.g., 8-9 AM to 6 PM) and fasting for the remaining 14-16 hours, as this is an easy and safe way to allow your body to use stored energy.
7. Avoid Overeating Post-Fast
Do not view fasting as permission to overeat or consume unhealthy foods during your eating window, as it’s crucial to combine fasting with healthy, nutritious, whole foods for effective results.
8. Combine Fasting with Healthy Diet
Integrate periods of fasting with a diet of healthy, nutritious, whole foods, recognizing that both what you eat and when you eat are equally important for achieving health and weight goals.
9. Consume Acidic Foods with Carbs
Pair acidic foods like vinegar, lemon juice, or fermented foods with carbohydrates to significantly lower their glycemic and insulin response. Acids deactivate salivary amylase, reducing starch breakdown.
10. Eat Carbohydrates Last in Meals
Shift the order of your food intake by consuming protein and fat first, and carbohydrates last, within a meal to reduce the insulin response and promote satiety.
11. Drink Non-Caloric Beverages While Fasting
During fasting periods, stick to non-caloric drinks such as water, teas (including herbal), and coffee, as these have minimal hormonal impact and support the fasting state. A small amount of cream in coffee is generally acceptable.
12. Consult Doctor for Diabetes Medication
If you are taking medication for type 2 diabetes or other blood sugar-lowering drugs, always consult your healthcare professional before starting any fasting regimen, as it can dangerously lower blood glucose levels.
13. Maintain Muscle Through Exercise
Understand that muscle loss is primarily due to lack of use, not fasting; therefore, engage in regular exercise to preserve and build muscle mass, especially during periods of weight loss.
14. Incorporate Monotonous Meals
Consider eating more monotonous meals, as the reduced hedonic (pleasure-giving) effect of repetitive food choices can help you eat only until satiety, preventing overconsumption.
6 Key Quotes
The energy balance equation is always true, but people always misinterpret it to mean that just eating fewer calories leads to body fat loss. It does not.
Dr. Jason Fung
When you're eating, you're storing calories. When you're not eating, you're using calories. That's, that's all it is.
Dr. Jason Fung
Food is so much more than calories. Food is information. Food has an impact on inflammation. It has an impact on genetic expression. It does so much. It's, it signals so many things in the body, which we really undervalue when we just say how many calories is in that.
Dr. Rangan Chatterjee
Some foods are more fattening than other foods, which is, of course, an idea that your grandmother would have thought, blindly obvious, right? Like, who gets fat eating broccoli? Like, zero people in the whole world. Who gets fat eating cookies? Many, many, many people, right?
Dr. Jason Fung
The human body is run by hormones. That is the chemical messengers that tell our body what to do. And this idea that it comes down to something so simplistic like calories. Calories is such a terrible notion because it's not terrible. It's just misused because it's a unit from physics, not physiology.
Dr. Jason Fung
Do you really think that our body is just so stupid that we would store calories as glucose and body fat, but the minute that you don't eat anything, you're going to burn muscle? Like, do you think that we survived as a species to become the dominant species on earth because our body is so intrinsically stupid?
Dr. Jason Fung
2 Protocols
Starting Intermittent Fasting
Dr. Jason Fung- Aim for an 8-10 hour eating window, for example, eating between 8-9 AM and finishing by 6 PM.
- Cut out snacks between meals.
- Eliminate late-night eating.
- Allow the remaining 14-16 hours to be a fasting period.
Optimizing Food Consumption for Lower Insulin Response
Dr. Jason Fung- Prioritize eating whole, unprocessed foods.
- Reduce intake of sugar and refined carbohydrates.
- Consume protein and fat components of a meal first.
- Eat carbohydrate-containing foods last in the meal.
- Consider adding acidic elements like vinegar or lemon juice with carbohydrate-rich foods.