The part obesity plays in the development of osteoarthritis would appear straight forward. Excess body weight loads up the joints and this extra pressure leads to pain and joint failure. Yet obesity being a risk factor for hand osteoarthritis has been known for many years. As we do not walk on our hands, how is it that obesity can cause joint damage in a non weight bearing joint?

A recent publication in the <a href=”https://www.mja.com.au/journal/2016/204/2/not-just-loading-and-age-dynamics-osteoarthritis-obesity-and-inflammation” target=”_blank”>Medical Journal of Australia</a> highlights findings that increased body fat is associated with early through to late osteoarthritis. It goes on to explain that body fat is not an inert structure but rather a highly metabolically active tissue that produces lots of nasty chemicals and inflammatory molecules that have been shown to damage joints. This type of low grade obesity – induced inflammation is known as ‘metainflammation.’

These findings challenge the idea that osteoarthritis is just a degenerative disease and that it is much more complex than just wear and tear.

Studies looking at obesity found an effect of obesity as a risk factor for knee osteoarthritis. We measure obesity with body mass index (BMI) or your weight but in many medical fields such as diabetes, and cardiovascular disease there was a move to separate body composition because two people can have the same BMI but one person can largely have muscle and the other a majority of fat.

When looking at body composition, the studies found that osteoarthritis was being driven by the amount of fat a person was carrying.

It is also important to keep in mind that metainflammation can occur with a weight gain as little as 4 or 5 kilos. Increasing weight will then contribute increased mechanical load on the joints which are now experiencing low grade inflammation.

Currently the medical profession tends to see older patients present with osteoarthritis by which time joint damage has already occurred. These findings highlight the importance of preventing weight gain much earlier in life; which is more achievable than trying to lose excess weight later in life.