Davo if you want to give it a go on the chopped rats by all means go for it, but thats just a messy ride all on it's own. Irish the reason is not powerfeeding as much as it is adequate choices in temps. Monitors need a range of 120 -110 depending on species and habitat. Desert and savannah monitors like ackies and or niles (comparing an odatria vs a larger species) both thrive on cool temps and very hot hot hot dry temps (africa and aus) where as a species like indicus or doreanus will need a more constant temp around 110 at the hottest point (under the basking light) to ambients from 90 to the low 70's at the cages coolest points. Ackies like cooler temps and they will use more often than we think. In my ackie cage i have a basking of 135 and ambients in the high 60's I use one bulb for a 6 foot trough and directly under the bulb the temps are at 135 (directly underneath) to around the high to low 90's around the immediate area and as you get to the other parts of the cage it will drop to the 80's then 70's then finally high 60's. I have ackie burrows going from one end to the other. This approach is used only with my desert monitors. Ackies, gouldii complex, the tristis complex and when I had albigs (south african whitethroats). I would never try this approach with my prasinus or my kimberly rocks for that matter. I use more arboreal setups that maintain ambient temps in the high 70's and use a lower wattage bulb to attain the 110 basking spot. So if i was to go and look at all these obese niles savs salvators albigs and even ackies ( which I have) it all boils down to the way keepers are keeping these animals. Their temps are probably bad, humidity is bad, the animal is stressed lack of hides substrate depths etc.... these are all factors that stress the animal out. The animals will continue to eat no matter how much you offer it providing that it has halfway decent conditions IE heat lamp etc....., but these animals need variety in order to properly digest these foods. They still pass food and will be hungry. But the animal will still store unnecessary fat, because of a lack of better options. It like if I went to Mac Donald's everyday and ate. I would still be hungry the next day, but I wouldnt be able to pass the fat storage due to my improper conditions. This is of course if I were to not exercise and not be in the right state of mind. We have to remember that we have to provide for these animals in a box what nature provides them in vast territories. Keepers need to be more aware that varanids are far more advanced and highly intelligent for being reptiles. They need to be challenged and stimulated daily in order for them to be in the right state of mind. For those varanid keepers here sit down in front of your enclosure and let your monitor tell you what is wrong with it. Much the same way we sit in front of our tanks to figure out a problem with our fish.