A new study has raised fresh concerns about the level of obesity-related illness in the UK.
The research found nearly four million people weighing a "normal" amount could actually be in danger of suffering diseases linked to being overweight.
Nutrition expert Dr Margaret Ashwell looked at obesity data from the latest National Diet and Nutrition Survey and waist circumference measurements.
The study, which was conducted on behalf of Lloydspharmacy, found 3.6 million people with a "normal" body mass index (BMI) could still face problems such as diabetes and heart disease due to the way their fat is distributed.
BMI calculates the suitable weight of a person in relation to their height, but Dr Ashwell said people should not look at it as the only measure of general health.
"It is vitally important that any screening problem to help the public minimise health risks encompasses an assessment of fat distribution - preferably using waist circumference - as well as BMI," she said.
Andy Murdock, from Lloydspharmacy, added: "We already knew that there is an enormous problem with too many people being overweight in the UK, but this new research shows that the problem of related heart risks might be bigger than previously thought, and that some normal-weight people have health risks that are not obvious from their weight alone."