Why do you crave dessert after dinner? Why are you hungry again an hour after eating? And why does weight sometimes seem to accelerate even when you're watching calories?

In Episode 3 of this series on ultra-processed and hyper-palatable foods, Dr. Brendan McCarthy breaks down the biology behind cravings, hunger, and weight gain. This episode connects the dots between food engineering, blood sugar spikes, insulin, and the brain’s reward system—showing why this isn’t a willpower problem, but a biological response to the foods we’re eating.

Dr. McCarthy, Chief Medical Officer at Protea Medical Center in Tempe, Arizona, explains how modern ultra-processed foods are designed to override normal satiety signals, destabilize blood sugar, and drive continued consumption. Over time, this can create hormonal changes that make weight gain easier and weight loss harder.

In this episode you’ll learn:

This series focuses on precision nutrition and endocrinology, helping you understand the real biological mechanisms behind metabolism, hunger, and weight regulation.

If you’ve ever wondered why controlling food intake feels so difficult despite your best efforts, this episode will help you understand what your body is actually responding to.

Citations: Episode 3 — Mechanism-Anchored Evidence Summary This episode explores how ultra-processed foods, liver metabolism, adipose tissue, hormones, and brain signaling interact to drive cravings, fat storage, and weight gain. Key mechanisms and supporting references include: Hepatic First-Pass Metabolism: Carbohydrates enter the liver via portal circulation, controlling post-meal fuel distribution (Samuel & Shulman, 2016). Fructose and Lipogenesis: Fructose bypasses key glycolytic regulation, fueling hepatic fat synthesis (Softic et al., 2020). De Novo Lipogenesis: Excess carbs activate SREBP-1c and ChREBP, producing triglycerides in the liver (Donnelly et al., 2005). VLDL Export: Hepatic triglycerides are packaged into VLDL and sent to adipose tissue (Adiels et al., 2008). Adipose Storage: Lipoprotein lipase delivers circulating triglycerides to fat cells (Kersten, 2014). Insulin Resistance: Hepatic lipid accumulation impairs insulin signaling (Samuel et al., 2004). Hyperinsulinemia & Fat Storage: Insulin promotes triglyceride storage and suppresses lipolysis (Czech, 2017). Aromatase & Estrone: Expanded adipose increases aromatase activity, raising estrone levels (Simpson et al., 1999; Key et al., 2002). Inflammation: Enlarged fat cells release cytokines, worsening insulin resistance (Hotamisligil, 2006). Ultra-Processed Foods & Overeating: Highly palatable foods drive excess calorie intake (Hall et al., 2019). Reward Signaling: Dopamine pathways reinforce eating behaviors (Volkow et al., 2013). Satiety Disruption: Low fiber and processed structure bypass satiety hormones like GLP-1 and PYY (Slavin & Green, 2007). Synthesis: Ultra-processed foods → rapid hepatic load → lipogenesis → triglyceride export → adipose expansion → estrone increase → inflammation & insulin resistance → cravings and repeated consumption. This creates a self-reinforcing metabolic cycle linking diet, liver, adipose tissue, hormones, and behavior.

Dr. Brendan McCarthy is the founder and Chief Medical Officer of Protea Medical Center in Arizona. With over two decades of experience, he’s helped thousands of patients navigate hormonal imbalances using bioidentical HRT, nutrition, and root-cause medicine. He’s also taught and mentored other physicians on integrative approaches to hormone therapy, weight loss, fertility, and more. If you’re ready to take your health seriously, this podcast is a great place to start.

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📘 Read Dr. McCarthy’s Book: Jump Off the Mood Swing – A Sane Woman’s Guide to Her Crazy Hormones https://www.amazon.com/Jump-Off-Mood-Swing-Hormones/dp/0999649604

📲 Follow Dr. McCarthy:

Instagram: @drbrendanmccarthy

TikTok: @drbrendanmccarthy

Website: www.protealife.com

💬 Got a question or topic for a future episode? Let us know in the comments!