Podcast Summary: Habits and Hustle - Episode 418: Dr. Jason Fung: Why Calories Are Not the Key to Weight Loss

Introduction

In Episode 418 of the Habits and Hustle podcast titled "Why Calories Are Not the Key to Weight Loss," host Jennifer Cohen engages in a deep and insightful discussion with Dr. Jason Fung, a renowned nephrologist and expert in intermittent fasting and low-carbohydrate diets. The episode, released on January 24, 2025, challenges traditional weight loss paradigms by emphasizing the critical role of hormones over mere calorie counting in achieving and maintaining a healthy weight.

Challenging the Calories In vs. Calories Out Paradigm

Jennifer Cohen opens the conversation by questioning the long-held belief that weight loss is solely a matter of balancing calories consumed with calories expended. She states:

"We've always heard, and me coming from the business background of health and fitness, that really it's about the calories you bring in versus calories out. And you're saying if you want to lose weight, that is actually, that's actually not correct information. It doesn't work as simplistic as that."
[01:51]

Dr. Fung immediately addresses the oversimplification inherent in the calories-in/calories-out (CICO) model. He explains that this approach fails to account for the complexity of the body's metabolic processes and hormonal responses to different types of food. Dr. Fung emphasizes that:

"It's not just the energy, it's what your body does with that energy. Right. So if you take 100 calories of cookies versus 100 calories of broccoli... the body can choose what to do with that energy, right?"
[02:12]

The Role of Hormones in Weight Regulation

Dr. Fung delves into the hormonal mechanisms that govern how the body processes different nutrients. He highlights insulin as a pivotal hormone that dictates whether energy is stored as fat or utilized for bodily functions. He articulates:

"Insulin is a hormone that promotes storage of those calories. So if you simply take foods that have a very high insulin stimulating effect, your body is going to want to store that because that's what you've told it to do."
[06:09]

Jennifer Cohen probes further into how hormonal changes, particularly those associated with aging, affect weight gain and fat distribution:

"Is that why when people are in their middle age or over 40, they tend to have more body fat?... they're still not losing that body fat."
[06:29]

Dr. Fung responds by correlating hormonal shifts with metabolic changes that occur with age, which can lead to increased fat storage despite reduced caloric intake:

"It really depends on the hormones within your body... the hormonal response to those foods is completely different."
[06:43]

Beyond Calories: The Quality of Food Matters

One of the key takeaways from the conversation is that not all calories are created equal. Dr. Fung challenges the notion that 100 calories of cookies are equivalent to 100 calories of broccoli, arguing that the body's hormonal response to these foods varies significantly:

"Calories in calories out is completely unphysiologic. There's no system within our body that simply monitors the calories in, calories out."
[07:50]

He further illustrates this by comparing calorie sources, stating:

"If you eat a block of wood, it has 100 calories, but it doesn't matter. Your body doesn't absorb it. It just goes right through you."
[08:10]

This underscores the importance of food composition in metabolic health, advocating for a diet that considers hormonal impacts rather than merely caloric content.

Insulin Dynamics: Carbs vs. Protein

Jennifer Cohen raises an important point regarding insulin spikes caused by different macronutrients, including protein:

"I think I heard you say on someone's podcast or even in your book, maybe that protein can even spike your insulin, which is something that I've never heard anybody say before. Is that like, how is that possible?"
[10:45]

Dr. Fung confirms that while protein does trigger insulin release, it simultaneously increases glucagon, a hormone that counteracts insulin's fat-storing effects. He explains:

"Insulin goes up, but then other hormones go up, like glucagon, it doesn't tend to have any effect on blood glucose as opposed to carbohydrates."
[10:50]

He further elaborates on the satiety effects of protein, noting that:

"If you eat protein, you're going to stimulate peptide YY, which is a satiety hormone and it's going to make you not want to eat."
[11:15]

This hormonal interplay ensures that high-protein foods are not inherently fattening, as they promote fullness and regulate appetite, contrasting sharply with the effects of processed carbohydrates and sugars.

Metabolic Adaptations and Weight Maintenance

The discussion also touches on how the body adjusts energy expenditure in response to caloric intake. Dr. Fung points out that:

"If you take less in, you're reducing your calories in, you don't necessarily reduce body fat. What could also happen is that if calorie what comes in goes down, what comes out, that's energy expenditure can also go down and your body fat can stay the same."
[03:30]

This highlights the body's ability to adapt to lower caloric intake by decreasing energy expenditure, making weight loss more challenging when solely focusing on calories.

Conclusion: The Importance of Hormonal Balance Over Caloric Restriction

Dr. Jason Fung concludes by reinforcing the idea that effective weight loss is rooted in understanding and managing hormonal responses rather than obsessively counting calories. He asserts:

"There's no way of measuring how many calories in. The only way our body knows is what to do with it is the hormones. And that's really what you have to focus on."
[09:50]

Jennifer Cohen summarizes the key insights, emphasizing the need to prioritize food quality and hormonal health to achieve sustainable weight loss and overall well-being.

Key Takeaways

1. Calories Are Not the Sole Determinant of Weight Loss: The hormonal response to different foods plays a crucial role in whether consumed calories are stored as fat or utilized for energy.

2. Insulin's Central Role: Insulin regulates fat storage. Foods that spike insulin levels, such as processed carbohydrates and sugars, are more likely to contribute to fat accumulation.

3. The Quality of Calories Matters: Whole foods like vegetables and proteins elicit different hormonal responses compared to processed foods, making them more conducive to weight loss and satiety.

4. Metabolic Adaptations Complicate Weight Loss: The body can adjust its energy expenditure based on caloric intake, often hindering weight loss if only calorie reduction is attempted.

5. Protein's Dual Effect on Insulin: While protein can increase insulin levels, it also elevates glucagon and satiety hormones, mitigating its impact on fat storage.

6. Hormonal Balance Over Caloric Counting: Sustainable weight loss and health are better achieved by focusing on hormonal regulation through food choices rather than merely counting calories.

Notable Quotes

• "Calories in calories out is completely unphysiologic. There's no system within our body that simply monitors the calories in, calories out."
  — Dr. Jason Fung [07:50]

• "Insulin is a hormone that promotes storage of those calories. So if you simply take foods that have a very high insulin stimulating effect, your body is going to want to store that because that's what you've told it to do."
  — Dr. Jason Fung [06:09]

• "If you take a block of wood, it has 100 calories, but it doesn't matter. Your body doesn't absorb it. It just goes right through you."
  — Dr. Jason Fung [08:10]

• "You have to look beyond the calories and you really have to look at what the information contained within that food is as to what your body's going to do with it."
  — Dr. Jason Fung [07:20]

Final Thoughts

Episode 418 of Habits and Hustle provides a compelling argument against the traditional calorie-centric approach to weight loss, advocating instead for a nuanced understanding of hormonal impacts. Dr. Jason Fung's insights encourage listeners to rethink their dietary strategies, emphasizing hormone regulation and food quality as essential components of a healthy and sustainable weight loss journey.