More than a quarter of obese and overweight people do not want to lose weight, a survey says.
Many people could not identify their weight category
The Cancer Research UK poll also found many more were unaware of the benefits of a healthy lifestyle and that being overweight increased cancer risk.
The poll of 4,000 people came as the charity and Weight Concern published 10 weight management tips.
They include keeping regular meal times, walking 10,000 steps a day and snacking healthily.
WEIGHT MANAGEMENT TIPS
Keep to your meal routine
Choose reduced fat versions of food
Walk 10,000 steps - equivalent of 60 to 90 minutes - each day
Pack a healthy snack
Check fat and sugar content of foods
Caution with your portions
Break up your sitting time by standing up 10 minutes each hour
Drink water and sugar-free squashes and be aware alcohol is high in calories
Don't eat food quickly
Eat at least five portions of fruit and veg a day
More than half of the 4,000 people polled were overweight or obese, but 26% of them said they did not want to lose weight.
Some 87% of obese and 32% of overweight people were unable to identify their weight category.
And nearly three-quarters said they did not know there was a link between cancer and weight and nearly half did not believe eating healthily could reduce cancer risk.
Obesity is linked with an increased risk of bowel, kidney, oesophageal and stomach cancers, as well as cancer of the womb and breast cancer in post-menopausal women.
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "It is worrying to think that people are in denial about their weight.
"People who carry extra weight face significant health risks including cancer.
"Obesity is one of the biggest known preventable causes of cancer for those who don't smoke.
"These results show too many of those at greatest risk are choosing to ignore their weight."
Weight Concern executive director Caroline Swain said the lack of concern about obesity was worrying.
"Education and support are a vital component in tackling the alarming rise in obesity in this country."