The obesity crisis is largely down to environmental factors, not a lack of self-control from the overweight, according to the Government's top adviser on the problem.
Susan Jebb, professor of diet and population health at the University of Oxford, believes that it is not overweight people's fault that some find it so hard to eat less.
The impact of an individual's genes, as well as the wide availability of unhealthy snacks, can make it more difficult to cut down on food than most people realise, she told The Times.
Speaking ahead of her appearance at The Times Cheltenham Science Festival this summer, Professor Jebb, the senior obesity adviser to Public Health England and the National Institute for Health and Care Excellence, gave her opinions of the causes of the nation's weight problem.
"Obesity has increased so greatly over the last few decades. That's not a national collapse in willpower. It's something about our environment that has changed," she said.
"You need in some cases a superhuman effort to reduce your food intake. Is that their fault? I don't think it is."
Her comments come after scientists warned last week that roughly a fifth of the human race will be obese by 2025.
In a recent study of Body Mass Index trends, published in The Lancet medical journal, the UK had the third highest average BMI in Europe for women (27kg/m2) and the 10th highest for men (24.4kg/m2).
Discussing the biological factors in tackling weight loss, Professor Jebb said: "If you're the kind of person (for whom) it takes a lot of food to make you feel full, of course you're going to have a harder time controlling your food intake.
"Some people (with normal weight) have a view that people could eat differently, but there's good biological evidence that . . . it's much harder."