Obesity is strongly associated with osteoarthritis, and in particular a dose dependent relationship has been found to exist between BMI and risk of developing osteoarthritis of the knees. Excessive osteoarthritis of otherwise healthy joints is known to contribute towards osteoarthritis, but obesity is also a risk factor for developing osteoarthritis in non-weight-bearing joints, and current research indicates a more complex relationship exists between osteoarthritis and obesity than can be explained by biomechanical stress alone.

Cancer is the name for a group of diseases in which cells in a specific part of the body divide and grow abnormally to form clusters known as tumors. All body tissues are formed from cells whose behavior is governed by genes. Under normal circumstances, cells reproduce and die at an equal rate, but if the gene responsible for controlling this aspect of cell behavior changes or mutates then the cell can begin to replicate uncontrollably. Whilst the link between cancer and obesity has been the focus of significant research for some time, no single causal pathway has been identified and at present it is not clear whether obesity is responsible for causing the gene mutations that can initiate cancer, or if it somehow promotes cancer progression such that the disease is detected at an earlier age than would otherwise be typical