Over grooming behaviour in cats
As a behaviourist it is very important to get to the motivation and emotion behind the behaviour because without changing the emotion the behaviour does not change.
A cat grooms for different reasons you may find that they groom the base of their tail or in-between their shoulder blades when they are feeling frustrated. You may find that a cat grooms when they have finished eating their food.
Excessive licking on a particular area can involve hair loss or even bleeding and scabs in that particular area. When it becomes compulsive it carries on occurring at a level that is not normal. Sometimes over grooming can be in response to some stressors in the environment – this could be something as simple as a cat walking past in the garden while your cat is eating.
Medical
If a cat is licking their abdomen it may be that they are suffering from a lower urinary tract infection so it is important to speak to your vet.
References
Trudi Atkinson. Practical Feline Behaviour : Understanding Cat Behaviour and Improving Welfare. CAB International, 2018.