The American Institute for Cancer Research (Aicr) says growing food portions are contributing to obesity in the United States.

While it says individuals bear the ultimate responsibility for what they eat, the AICR has chided food manufacturers and the restaurant industry for distorting what constitutes an appropriate meal size.

It noted portions have increased significantly, citing as an example the quadrupling of a single order of chips from their 1955 size.

AICR research found 30% of people surveyed base the amount they consume on how much they are served and concludes that bigger portions encourage overeating by as much as 56% over usual habits in men and 31% in women.