But they have left many of them so overweight they can hardly get around.
About 50 Macaca mulatta monkeys at Ohama park in Sakai, Osaka Prefecture have been so overfed by tourists they are now massively overweight.
A local report in April said that about 30 per cent of the animals are so huge they struggle to get around their 420-square-meter enclosure.
Officials have been forced to put them on a strict diet.
A healthy Macaca mulatta monkey weighs about 20lbs, but one of these chunkies is over 4st.