Eat breakfast like a king, lunch like a prince and dinner like a pauper!
or
Eat like a king in the morning, a prince at noon, and a peasant at dinner
The abovementioned proverb doesn't mention how, for example, eating like a king
is defined nor does it contain any reason why one should do it, but it is safe to assume that following it would be seen as healthier than any other distribution / relation of the amount eaten per mealtime, assuming that we eat three times a day.
Here are some sources to show that this is a notable claim:
- http://www.dailymail.co.uk/health/article-2282413/A-large-lunch-small-dinner-really-IS-key-keeping-trim.html
- http://www.huffingtonpost.co.uk/diana-moran/healthy-eating-advice-diana-moran_b_5379697.html
- In books: https://www.google.com/search?tbm=bks&hl=en&q=Eat+breakfast+like+a+king%2C+lunch+like+a+prince+and+dinner+like+a+pauper!&gws_rd=ssl
Is it healthier to eat a lot in the morning, less in the noon and little in the evening?
, but the proverb is definitely often understood that way. (Just search for one version of it and look at what people write about it.)