Serving sizes have increased dramatically in recent decades. It’s happened so subtly that many of us simply don't realise, but it’s having a serious impact on our health and our planet. So, how can we reverse it? Emily Thomas learns how food manufacturers and clever marketers have nudged us into buying ever larger portions, leveraging ultra cheap ingredients and our own psychology. We hear that the phenomenon is so pervasive it’s also crept into the home, where many of us have lost any concept of what an appropriate portion is. Given the increasing awareness of the poor health and environmental outcomes linked to overconsumption, we find out what regulators and companies are doing to shrink portions back to a more sustainable size, and ask whether the real answer might lie in a fundamental shift in the way we all value food. Producer: Simon Tulett If you would like to get in touch with the show please email thefoodchain@bbc.co.uk (Picture: A woman drinking from a giant coffee cup. Credit: Getty/BBC) Contributors: Pierre Chandon, professor of marketing and director of the INSEAD Sorbonne University Behavioural Lab, Paris; Theresa Marteau, director of the behaviour and health research unit at Cambridge University; Denise Chen, chief sustainability officer at Melco Resorts & Entertainment, Hong Kong.