Obesity can seem straightforward to explain. If a person consumes more calories than they need, they gain weight. But the real explanation is not that simple. And it is about more than weight.

Obesity is a complex chronic disease, and losing weight is not just a question of eating less and moving more. In fact, obesity can be influenced by genetics, physiology, environment, job and education, and what is going on in the brain.

Understanding these factors is critical, because obesity is associated with other diseases, including type 2 diabetes, heart disease and certain types of cancer. Not to mention the stigma and bias millions suffer every day.

But with the right care, people with obesity can achieve sustained weight loss that really makes a difference to their health.

Today we know that obesity is a serious chronic disease, not simply a matter of effort. 

Together with our partners, we are committed to driving change in how the world sees, prevents and treats obesity. As leaders within the science of obesity, we are working to make obesity a healthcare priority, defeat stigma and support better access to evidence-based care.

Obesity is influenced by many factors both inside and outside of the body. A person could be born with a tendency to put on weight. Just as someone is born with a particular eye colour.

There is also the physiological aspect. When a person eats, hormone signals from the stomach and gut are translated into feelings of reduced hunger and increased satiety. This controls a person's food intake.

During weight loss, the level of hormones can change in an attempt to regain the lost weight. As a result, studies show that only about one third of people successfully maintain their lost weight.

Many aspects of a person's general well-being, environment and lifestyle can also cause weight gain. Where a person lives and the culture that surrounds them can also influence the risk of developing obesity.

So, although many people with obesity believe they should be able to manage their weight on their own, it is not that easy. 

To understand obesity, we must understand what is going on in our brains. It seems our bodies are hard-wired to hang on to those extra calories, probably because for thousands of years, it was a basic survival mechanism.

Therefore, people living with obesity struggle to lose weight. Their bodies programming works to get them back to their original starting weight. In the brain, it's as if there is a switch that tweaks a person’s energy expenditure until they have regained the lost kilos.

We are trying to pinpoint where exactly in the brain such a switch could be located and exploring whether it is something we could address with a medicine. So that one day, we might be able to help people with obesity to ‘reset’ their weight to a new, healthier starting point.

If we succeed, we could help millions of people living with obesity.