In some but not all geographies dog owners in general have a propensity to provide more foods than exercise to their dog, and so their dog ends up being obese from around 8 years of age when the dog's metabolism naturally slows down and the dog's body requires and processes less food. The same is true for German Shepherd Dog owners, as we know from the data that dog owners input on our website (both in the Periodical subscription form, and in the GSD Online Health Assessment form).
The ramifications of Obesity in dogs are the same as for people: Arthritis, Diabetes, Pancreatitis, Kidney failure, heart disorder and defect, etc. For the German Shepherd, these consequent health disorders just materialize much quicker than for people, because a) the GSD's life span is so much shorter, and b) the GSD is a high metabolism high activity dog, and so degradation of individual cells and overall body is much quicker.
Speaking of it, be aware that when you do extreme sport with your German Shepherd, your dog will wear out markedly sooner. Not just sooner than (s)he otherwise would, but sooner than say a Terrier breed dog. Short-term fun at the cost of reduced quality of life at age. Therefore consciously choose what you really want for, and with, your German Shepherd - as long as you can't ask your dog what (s)he wants.
Insights like these make clear why it is foolish-squared when average ordinary allopathic veterinarians only treat the reported symptom, say Arthritis, Diabetes, Pancreatitis, Kidney failure, or whatever. - We'll leave out heart disorder and defect here because ordinary vets cannot differentiate between disease, disorder, and defect (you may want to test your own vet now), hence why they wrongly speak of heart disease.
When you only treat a symptom but not cure the cause, then you cannot cure the patient! Obvious, isn't it? While for you and your dog that's BAD, for the average ordinary allopathic veterinarian that's
GOOD GREAT: You'll have to come back with further health issues down the line, which allows such vets to charge you further bills year after year after year after year...
Back to overweight at age. Make sure that when you notice that your German Shepherd is slowing down, that you don't force your older dog to some exercise that (s)he seems unwilling to do (mild encouragement, no more). But also, reduce the food in line with the reduction in daily exercise (no more). Keep water provision plentiful though.
Completely avoid commercial treats, and the meals that you serve your dog ideally are homemade and high in veggies and fruits.
If only you follow the bit of advice above, your GSD will not end up overweight at age.
Note that every key point raised above you can find more comprehensively explained in other places on this website. The menu is your friend. Here, links have been omitted only to keep this decision tree straightforward.
PLEASE NOTE: Posting a fragment of your overall dog problem in the comments below is not going to help. Provide complete details if you really seek the right solution. Of course we have a page for that as well: Dog Problem Consultation.