Top Neuroscientist: The Hidden Forces Making You Regain Weight (+ How To Beat Them)

March 25, 2026

AI Summary

5 min read

In a study of over 4,500 people, Dr. Susan Pierce Thompson’s data showed no difference in weight loss ability based on age—whether someone was in their twenties or their seventies. That finding contradicts a widespread belief that menopause or aging makes weight loss impossible. But the reason, she explains, is that the difficulty older women face with weight loss is largely driven by insulin resistance, which is exacerbated by eating refined sugar and flour. Remove those from the diet, and the playing field levels. This is one of many counterintuitive claims in a conversation that centers on a sobering premise: your brain is wired to regain weight, and it will fight you for years—possibly indefinitely—after you lose it.

Why the Brain Fights Weight Loss

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What you'll learn

1 (00:00) **The Brain's Weight Regain Wiring** - Introduction to the core problem: your brain evolved to regain lost weight, making long-term maintenance biologically hard
2 (06:30) **GLP-1s: Hope, Limitations, and Off-Ramp Strategy** - Discussion of whether you can go off GLP-1s without regaining weight, and what would need to change
3 (10:23) **Why Refined Sugar and Flour Hijack Your Brain** - The metabolic and neurological difference between whole foods and refined carbohydrates
4 (15:03) **Cravings, Extinction, and the Three-Week Hump** - How long it takes for cravings to disappear and what makes the process harder
5 (19:55) **Dr. Thompson's Personal Story: From Crack Addiction to Food Addiction** - How her history of severe addiction informs her approach to weight management
6 (37:24) **Three Deep Identity Shifts for Long-Term Weight Maintenance** - The psychological work required to keep weight off, regardless of how you lost it
7 (41:33) **Willpower: Why It Fails and How to Work Around It** - The neuroscience of willpower depletion and the solution of automaticity

+ Full timestamped outline available in the app

Show Notes

Your brain is designed to regain weight you’ve lost. It is not a failure on your part—it is literally how your brain is wired. But it turns out, there are ways to outsmart it. This is the missing piece of weight loss that no one is talking about. In this episode, we get into why so many people struggle with losing weight and keeping it off longterm. The good news is, once you understand the science at play, there are tools you can use to finally break free, to rewire your brain so that you don’t need to white knuckle your way through life, and you can get the results you want and FEEL the way you want.

My expert guest is Susan Peirce Thompson, a neuroscientist, professor, best-selling author, and the founder of Bright Line Eating.

Wherever you’re starting, whatever you’re dealing with, this episode is going to give you hope and new information you won’t hear anywhere else.

🎧 What you’ll learn:

• Why your brain is so resistant to losing weight and exactly what you can do about it

• Why so many people regain weight after going off GLP-1s (and what you can do differently if you want to maintain your weight loss)

• How to break through weight loss plateaus

• The reason you get cravings and how to make them stop

• 5 science backed ways to increase your willpower

• Why you might want to STOP exercising if you want to lose weight

Check out the previous episode of The Liz Moody Podcast discussed today:

This Celeb-Beloved Therapy Offers A Radical New Way To Heal With Dr. Richard Schwartz

Check out the resources mentioned in today’s episode:

• https://www.foodaddictionquiz.com

• https://www.jointhemaintenancemovement.com

For more from Susan Peirce Thompson, Ph.D.:

• Website: https://www.susanpeircethompson.com/

• Book, Maintain: https://www.jointhemaintenancemovement.com/#Order

• Instagram: https://www.instagram.com/brightlineeating

Ready to uplevel every part of your life? Order Liz’s book 100 Ways to Change Your Life: The Science of Leveling Up Health, Happiness, Relationships & Success now!

Connect with Liz on Instagram @lizmoody or online at www.lizmoody.com. Subscribe to the substack by visiting https://lizmoody.substack.com/welcome.Buy our cute sweatshi