Presenter biographies: J to L

Dr Susan Jebb is a nutrition scientist and leads a research team at the Medical Research Council, Human Nutrition Research Unit , studying dietary factors in the origins and treatment of obesity and related metabolic diseases.

She is former head of the UK Association for the Study of Obesity and an honorary officer of the European Association for the Study of Obesity.

Susan also provides nutrition and obesity advice to the Government, as well as to industry and the media.

She was a consultant on the BBC Two series The Truth About Food.

Dr Jenkins is a part-time GP in Bristol, working in a large practice in the day and also as a director and GP for one of the city's GP out-of-hours services. She has a particular interest in diabetes, heart disease and the effect of lifestyle on health including obesity, parenting and travel.

She also works as a freelance medical journalist and broadcaster and is a flight doctor for an air ambulance/medical repatriation service.

Heather is a freelance writer covering health, lifestyle and social causes. She has worked in health education for more than 12 years, and now combines this with a career in journalism and social marketing.

Dr Lang is the external affairs officer for the UK Association for the Study of Obesity (ASO). She has with the Medical Research Council and ASO to provide nutrition and obesity information to the academic and consumer press.

She's a registered expert with the Science Media Centre and the Nutrition Society, and is a member of the British Dietetic Association.

Tony is an applied sports scientist and sports rehabilitation specialist.

He's a research associate at the centre for sport and exercise science at Sheffield Hallam University, and provides sports science and medicine support to the Lawn Tennis Association and the All England Netball Association.