MOST dieters vastly underestimate how many calories they are eating -- according to their GPs.
Data from 10,000 slimmers and 200 doctors found 87pc of GPs believe dieters are in the dark about how much they actually eat.
Meanwhile, more than nine out of 10 people (92pc) see their dieting attempts end in failure, with 18pc ending up weighing more than when they started.
Only around one in three (32pc) take more exercise when trying to lose weight, while only 23pc check food labels before buying.
Most (91pc) never weigh out food or control their portion size.
Overall, 90pc of GPs said people needed to change their eating habits and that losing excess pounds can be as hard as quitting smoking.
Two-thirds (66pc) regard overeating as a form of addiction, while 73pc of GPs said fad diets do not work, despite 51pc of Britons having tried them.
Nutritionist Dr Chris Fenn said: "People need to adopt a personalised approach to weight loss tailored to their own situation, challenges and strengths.
"They need to understand the causes of their weight gain and the barriers to weight loss, including their relationship with food.
"People are often ill-prepared to lose weight and underestimate what is required."
The survey was commissioned by Shape.Smart, which makes diet products.