The durability of your toilet seat is quite dependent on the level of care taken to maintain its integrity as an overweight toilet seat. Therefore, the time period before you change your heavy-duty toilet seat is determined by how much care you take. A well-maintained oversized toilet seat would last for more than a decade. However, if your toilet is characterized by a lot of shifting, heavy plunking or poor cleaning then you may need to replace your toilet seat after a period of five years or less. This is a common characteristic for commercial based toilet seats for fat people.