The Exam Room by the Physicians Committee Why Ultra-Processed Foods Can Sabotage Your Weight Loss | Dr. Jim Loomis
Dec 18, 2025
Dr. Jim Loomis, medical director at Barnard Medical Center and co-host of Doc & Chef, dives into the hidden dangers of ultra-processed foods in the quest for weight loss. He explains how these foods disrupt appetite hormones and promote fat storage, making weight control a challenge. Discover the significance of fiber, nutrients, and the thermic effect of food in managing weight. Dr. Loomis also shares practical tips for choosing whole plant foods and breaking free from harmful eating habits.
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Processing Strips Satiety Signals
- Ultra-processed foods remove fiber and key nutrients, which breaks the gut-brain feedback that signals fullness.
- That stripped package causes rapid absorption, insulin spikes, and more fat storage compared with whole foods.
Calories Depend On Food Packaging
- Calories behave differently depending on the food "package" they come in, not just their biochemical content.
- An apple slows digestion and raises thermic effect, while juice spikes sugar despite equal calories.
UPFs Hijack Hunger Hormone Signals
- Ultra-processed foods short-circuit GLP-1 mediated signals that slow gastric emptying and curb hunger.
- That disconnection explains why people can eat large quantities of ultra-processed snacks without feeling satisfied.