Healthy eating: What is a correct food portion?
Nutrition scientists have devised a new way of measuring out food portions - using your hands, thumbs and fists rather than a set of scales.
The new guide from the British Nutrition Foundation has been created after studying portion sizes around the world and what is available in UK supermarkets.
It is thought that better portion control could lead to people being healthier - taking pressure off the NHS. It could also save customers money and it would be better for the environment as less food would be wasted.
The BBC's Health Reporter Laura Foster explains some of the key portion measures that often catch people out.
You can see full details on the guide here.