I have helped countless pet parents get their pets' weight issues under control and every single case has taught me something new regarding the human-animal bond and the psychology of caring for a pet. While there is a large guilt component that needs to be overcome, in all cases love is the underlying cause of every weight issue I see. Not one pet who is overweight became so because they were mistreated or abused. They became overweight because the love their humans felt for them was shown through food. Giving a treat is instant gratification for both pet and parent and because pets so enjoy treats, often it's difficult to stop at one...or two...or well maybe just one more. The issue with this is obesity sets our pets up for ill health and shortened lives which can result in an often overwhelming sense of guilt. Our pets are entirely dependent on us for life and when we do them harm (and in the case of obesity, the harm in wholly unintentional), the feeling of guilt is proportionate to the amount of love we feel for them. Sometimes the hardest hurdle to overcome with weight issues in pets is getting acceptance from pet parents that there is an issue and I believe part of the reason for this is for them to acknowledge that their pet is overweight or obese is to acknowledge that they have caused harm but by allowing this guilt to take hold, the journey to a healthy weight will never start.
The first step in helping pets lose the weight is to acknowledge the love that contributed to the weight gain and refocus it towards making the changes in habits that love created.