Fish and chip shops should standardise the size of their portions to help combat obesity, according to an industry body.
Such a move would also help boost profits, Seafish has said in its annual report.
The organisation commissioned a survey which shows that the size of a medium fish can vary by over 500% across the UK.
In some shops a regular fish can be as small as 97g, while in others they are a whopping 562g.
Chip portions vary by almost 700%.
The report said: "Fifteen per cent of consumers think that chip portions are too big and 44% of them even end up throwing some of their chips away.
"Making portion sizes more predictable and offering customers more portion size options could make businesses more competitive."
Whitby's award-winning Quayside Fish Restaurant offers two sizes of fish: small (5oz or 142g) and regular (9oz or 255g).
Manager Adam Sheldon told Sky News: "Some chip shops give bigger portions to appear competitive but that often leads to waste.
"We notice that a lot of people, particularly lunchtime customers or locals who eat fish and chips more regularly, enjoy the option of smaller portions."
Nutritionist Deborah Naylor said consumers are more health and diet aware, and want more accurate information about the food they eat.
"Standardised portions and nutritional information would mean people could plan their diets more easily," she said.
"Consumers rightly want to know more about the amount of calories and fats in food, to allow them to make more informed decisions."
The survey backs up her theory.
It shows that over 50% would like to know the fat content of their meal, and more than 60% would like to see nutritional information displayed per portion size.