Even at its peak, the customers of Eagle Boys Pizza were among the least loyal in the fast food game and ready to permanently abandon the chain, new data shows.

In the year to March, nearly 5 million Australians over 14 years of age visited or ordered from a pizza chain in the past month, up very slightly on the figure five years ago, according to research firm Roy Morgan.

Over the past half decade, the top chain Domino's Pizza was able to boost customer numbers by 28 per cent to 2.2 million - an extra half a million.