This is a tough one. In the average human body there are probably hundreds of thousands of fat cells (but remember that most cells are tiny). But the actual figure will vary depending on the body fat content – so if a person is obese they may have a million or more fat cells. In obesity the fat cells are a lot bigger as well.
One interesting fact – the number of bacteria in your body and on your skin outnumber the entire number of cells in your body. But the bacteria are not usually harmful – they thrive of us and they help us to live a healthy life.