Yes, apple peels are an excellent fiber source for your overweight dog's diet. Fiber serves many purposes, but managing your dog's weight is the most imperative. Fiber fills your dog up without adding calories or fat. So, it's an excellent way to keep them feeling full without adding too much extra weight. Apple peels are perfect for this because they're low in calories and high in fiber. If you're concerned about your dog's weight, use apple peels instead of treats, but don't let them replace a balanced diet.