Harvard Doctor: Obesity, cancer, and the real cost of convenience food | Dr. Andy Chan

Ultra-processed foods now make up over half of what many of us eat - and the health consequences are only just coming into focus. In this episode, we reveal what’s really happening inside your body when you eat these foods daily. Our guest is Dr. Andy Chan, a Harvard professor and leading expert on gut health and cancer prevention. He heads the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital and has published over 400 scientific papers. Dr. Chan breaks down the hidden links between UPFs, inflammation, and diseases like obesity, diabetes, and colorectal cancer. You’ll hear why some foods that look healthy on the shelf may be doing long-term damage - and how the gut microbiome plays a crucial role in the process. This is the research big food companies don’t want you to hear. If you care about what you and your family are eating, don’t miss this conversation. Unwrap the truth about your food 👉 ⁠Get the ZOE app 🌱 Try our new plant based wholefood supplement - Daily 30+ Follow ZOE on Instagram . Timecodes 00:00 How much of our food is ultra-processed? 02:24 Can UPFs increase cancer risk in children? 04:48 Why our kids get sicker, earlier 07:12 How convenience took over our food choices 09:36 Are food companies engineering addiction? 12:00 UPFs and early onset cancer 14:24 Why calorie counting misses the point 16:48 Can a mother’s diet shape her child’s future health? 21:36 Is a poor diet as harmful as smoking in pregnancy? 26:24 Preservatives vs calories: what’s more harmful? 28:48 Brand new science: not all UPFs are equal 31:12 ZOE’s new processed food risk scale 38:24 Why UPF labels are misleading and confusing 40:48 A simple trick: how to spot UPFs on food labels 43:12 Should schools and offices be UPF-free zones? 45:36 How to shape your kids’ eating habits for life 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim Spector Free resources from ZOE Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks Mentioned in today's episode Trends in Adults’ Intake of Un-processed/Minimally Processed, and Ultra-processed foods at Home and Away from Home in the United States from 2003–2018 , 2025, The Journal of Nutrition Ultra-processed food intake in toddlerhood and mid-childhood in the UK: cross sectional and longitudinal perspectives , 2024, European Journal of Nutrition The Healthfulness of the US Packaged Food and Beverage Supply: A Cross-Sectional Study , 2019, Nutrients Ultraprocessed Food Consumption and Cardiometabolic Risk Factors in Children , 2024, JAMA Network Open Maternal consumption of ultra-processed foods and subsequent risk of offspring overweight or obesity: results from three prospective cohort studies , 2022, British Medical Journal Have feedback or a topic you'd like us to cover? Let us know here . Episode transcripts are available here .