The Boeing 777-300ER seats are approximately 17 to 18 inches wide, depending on the airline, making them comfortable for most people, but they may be too small for an obese person. The seats can be reclined and inclined during travel, but there isn't much room to move in each section.
When airline passengers are obese, it's possible that they may need to purchase two seats for the flight. The seats provided are designed for average-sized passengers within typical weight ranges. With some airlines moving toward 17-inch seats, those who are obese may want to purchase an extra seat for comfort during long-haul flights.