It is obvious that the more weight you carry, the harder your joints will work but most people don't understand how much of a difference it makes.
Take walking for example. The impact of our feet hitting the ground in walking creates a force equal to around three times our body weight. All of your weight is transferred through a single leg (while the other is in the air stepping forward) and we take thousands of steps a day.
What about running? The increased impact with the ground raises the forces to around 5 times body weight. This is a significant amount. Every extra 20 pounds of weight you carry means an extra 100 pounds of force through your knee every step you take when running.
And jumping? Does it get worse?
Yes - Landing from a jump brings the force through the knees up to the order of seven times body weight.
When you look at numbers like these it is easy to understand why weight loss is one of the most effective treatments of osteoarthritis.