Six people from across Britain, who are each living with obesity, travel the globe to learn the diverse reasons why people around the world are affected by obesity. Hosts in each country show them the traditional way of eating and forms of exercise in their culture and analyse their local obesity crises. The tourists learn the some alarming truths about the potential health effects of obesity and are weighed together at the end of each episode to find out if they've managed to achieve their individual weight-loss goals. They begin in Japan - one of the world's rare success stories, where obesity is almost non-existent. They discover that this has been achieved by extreme government intervention and a culture of shame, including peculiar fitness apps that scold people for their weight. Russell's thoughts turn to his father, who died from diabetes, and he decides to face his own fears and take on everything that is thrown at him, including stripping off for a Sento bath.