In this episode of A Whole New Level, Dr. Eric Ravussin, PhD, explains the physiology of energy expenditure, metabolic adaptation, and why the body strongly defends its prior weight. Drawing on decades of research, including the Biggest Loser study, CALERIE, and work with metabolic chambers, Ravussin walks through what actually happens when we lose weight—and why willpower alone isn’t enough.

In this episode, we cover:

Why BMI is an incomplete measure of obesity
The difference between preclinical and clinical obesity
How energy expenditure really works (and why larger bodies burn more calories)
What metabolic adaptation is—and why it persists long after weight loss
Why exercise alone rarely leads to sustained weight loss
How GLP-1 drugs intersect with appetite, metabolism, and muscle mass

🎙 What Dr. Eric Ravussin & Mike Haney discuss:

[04:40] — Rethinking obesity diagnosis

[07:00] — Clinical vs. preclinical obesity

[11:38] — What ‘energy expenditure’ actually means

[15:42] — What metabolic adaptation really is

[17:56] — Why bigger bodies burn more calories

[26:16] — Lessons from the Biggest Loser study

[31:19] — What CALERIE taught us about calorie restriction

[40:02] — Why slow, modest weight loss matters

[45:10] — Weight loss vs. weight maintenance physiology

[53:08] — GLP-1 drugs: promise and limitations

[57:49] — Why you can’t exercise your way to weight loss

[1:01:33] — The biggest myth about obesity

Levels helps you see how food affects your health, empowering you with the tools needed to achieve health goals and improve healthspan. Levels Members gain access to the Levels app and continuous glucose monitors (CGMs), providing real-time feedback on how diet and lifestyle choices impact your metabolic health.

Look for new shows every month on A Whole New Level, where we have in-depth conversations with thought leaders about metabolic health.

🔗 Helpful links:

Watch the conversation: ⁠https://youtu.be/UaE0C_l7GMw

Find us on YouTube: ⁠⁠⁠⁠https://youtube.com/levelshealth?sub_confirmation=1⁠⁠⁠⁠

📲 More about Dr. Eric Ravussin: https://www.pbrc.edu/research-and-faculty/faculty/Ravussin-Eric-PhD.aspx

#290 - Why Weight Loss Is So Hard to Maintain—Metabolic Adaptation Explained | Dr. Eric Ravussin + Mike Haney