I have a family member struggling with the medical condition obesity.
Sorry to here that. What can be done to help them?
Well to help with obesity, you can make changes to your diet. You can exercise more.
What exactly is obesity?
Obesity is when there is excess body fat that is results in a negative effect on ones health.
Is this a common thing.  I see a lot of fat people around but not sure if it is medical.
Its somewhat common. The most common casues of obesity is a combination of lack of physical activity, excessive food intake, and genetics.
By the way I'm fat too.  Should I see a doctor about this obesity thing?
You should try exercise and dieting first. Obesity is somewhat preventable through a combination of personal choice and social change.