Although it is a problem rooted in wider society, Dr. Stuart Flint, Associate Professor in the Psychology of Obesity at the University of Leeds, says negative attitudes around weight gain are pervasive in the NHS and they can affect the way patients are treated.

Writing a Comment article in The Lancet Diabetes and Endocrinology to mark World Obesity Day (March 4th), Dr. Flint argues: "A core value of the NHS is to provide a comprehensive service that is available to all.

"Despite this core value, many processes prevent it from being achieved.

"For instance, weight stigma and discrimination are common within healthcare settings and affects the quality of care that patients receive."

The All Party Parliamentary Group on Obesity has reported that only one in four people with obesity said they were being treated with dignity and respect by health professionals when they sought advice or treatment for their weight.

Ignorance about the scientific causes of weight gain is part of the problem. Dr. Flint says many people hold stereotypes where they believe individuals are responsible for their own weight gain because they are either lazy or greedy.

"Attributions of personal responsibility can lead to bias...with a person's health status perceived to be within an individual's control, which leads to fault and blame," he writes.

However research shows that obesity is "...a complex, multifaceted health condition that can be caused by, for instance, by genetics, epigenetics, biological, environmental, and societal factors."

Dr. Flint also compared the narrative around obesity with that for cancer in the NHS long term plan, highlighting that the language and framing of obesity may also contribute to weight stigma.

"The most striking difference is that the language used about cancer is positive, reflecting optimism and hope," he says. "When compared with obesity, the language is negative, reflecting pessimism, fear, and unpleasantness."

For example, people with cancer are discussed as survivors whereas obesity is seen as a burden.

Earlier this week, Dr. Flint launched a list of dos and don'ts to help MPs avoid loaded language when they discuss obesity.

The list suggests:

• Use object descriptions such as "weight" or "excess weight"
• Put people first—do not use 'obese people' but 'people with obesity'
• Be accurate in the description of the complex causes of weight gain
• Do not to imply there is a group of people who do not wish to manage their weight

The guidelines were drawn up in partnership with the charity Obesity UK and MPs on the All-Party Parliamentary Group on Obesity.

Mary Glindon, Labour MP for North Tyneside and chair of the All-Party Parliamentary Group, said: "Current efforts to reduce obesity simply aren't working.

"Weight stigma acts as a barrier to people with obesity seeking help and getting treatment.

"These guidelines will help MPs to lead the way in changing the way we speak about obesity, help to promote a wider understanding of the complexities of obesity, and help us move away from damaging stereotypes.

"Reducing obesity is not necessarily all about eating less and moving more."