Obesity is a risk factor for osteoarthritis. Being overweight or obese can place extra pressure on joints and cartilage, causing them to wear away. People with more body fat may have higher blood levels of substances that cause inflammation in the joints, raising the risk for osteoarthritis. Overweight and obese people who lost a substantial amount of weight over a 48-month period showed significantly lower degeneration of their knee cartilage, according to a new study published online in the journal Radiology.