Why are fatty tumors so common in dogs

Why are older dogs so prone to fatty tumors? I (mistakenly) assumed that if my dog had less fat on his body, his tumors would disappear. He's always been quite trim, but he has 2 movable, grape-like lumps that the vet said are fatty tumors. What causes them, and are there any natural treatments to make them go away? I worry because the second one arrived shortly after the first, and if I don't know what's causing them, I can't prevent them. My dog is mixed breed, short-hair, 11 years old. Thanks!

PET DISEASE AND ALLERGIES: FATTY TUMORS

Background: Composed of mature fat cells and connective tissues, a lipoma is a benign growth commonly felt beneath the skin in dogs. These "fatty tumors" are quite common in middle-aged and older female dogs, although they affect both sexes. Generally, they do not pose a serious health risk to pets, although occasionally they can grow quite large and begin to cause problems.

A tumor is a lump of cells that does not obey the normal rules of cell growth. Normally, cells grow until chemical messengers in the body tell them to stop growing. Tumor cells do not listen to these messengers and continue to grow. There are two types of tumor. The first type is called benign, usually growing slowly and does not generally spread to other parts of the body. The other type of tumor is malignant, which push through nearby organs or may spread to other tissues. Most fatty tumors are benign. They are neither painful, nor will they cause serious problems unless they grow between muscles or are so large that they cause mechanical problems, such as difficulty walking. Though rare, fatty tumors may become malignant, in which case they need to be surgically removed. Hopefully, your pet's tumor does not match any of the above criteria. It is very important that you keep a close watch on your pet's tumor. Although your pet's tumor is not a problem at this point in time, it may become a problem later down the road. It is good to document the size of your pet's tumor using general terms to identify the size (pea size, egg size). Each month you should reevaluate the size of the tumor. If any changes occur, you should contact your veterinarian immediately.