LIESBETH VAN ROSSUM
Internist-endocrinologist van Rossum of Erasmus University Medical Centre and the European Society of Endocrinology explains the complexity of causes behind the obesity epidemic
Why do you think fat is misunderstood? Many people do not know it’s an organ communicating with your brain and other systems. This organ of fat can be sick, just like a liver or a heart can be sick. If you understand the function of fat, then you can understand why it’s bad to have too much or too little. Obesity is about sick fat mass. One of the painful things about this is that the lack of knowledge also leads to stigma. I see my patients suer a lot from discrimination based on weight.
How does obesity impact your body after losing weight?
After weight loss, some immune cells are still dierent. It’s like a scar in the immune system. It’s called metabolic memory and it’s when your body knows that you once had obesity, and after weight loss it will try to regain fat to reach your older, higher weight somehow.
How long does metabolic memory last?
There are studies that show only short-term disturbances of just a couple of weeks, then there have been studies showing that even more than a year after stopping a diet these hormones are still disturbed. We don’t know whether it’s ever restored, but there are indications that some of the systems are being disturbed long term.
Why do we choose unhealthy foods?
If you’re stressed, you’re much more prone to chase chocolate, although you know a salad will be better. We make many food decisions a day. About 20 minutes after eating, you start to produce satiety hormones and they give you a sense of fullness. Your hedonic system concerns other hormones. That makes room for dessert when you’re full. And that’s because your reward system releases feel-good hormones. The third system to decide your food choice is your cognitive system. That’s very conscious, but a lot of your food choice isn’t about self discipline, it’s about unconscious systems. There are many ultra-processed foods, so we are already prone to eating more chocolate, for example, then you see the advertisements about chocolates, and your biological systems do respond to that.
How do you think endocrine research can bene t the obesity epidemic?
I’m fascinated by all the hormones that are produced by fat cells and other organs that all inuence each other. All over the world there are new discoveries about the role of hormones being produced by fat mass and other organs that have inuence on fat mass. We need a lot more research to really understand all the processes, but what we do understand is that too much fat can be a hormonal disease. Hormones don’t always induce it, but the hormones, genes and lifestyle combination induces obesity. Often we try to treat all the hormonal systems fat mass disturbs, but we should treat the fat mass itself. We also know there are endocrinedisrupting chemicals in products like the coee cups we drink from, children’s toys, furniture and cosmetics. People with obesity are more vulnerable to them because these chemicals love fat. They can enter fat easily and stay there, and this may impair weight loss. The more we know about the complexity of fat, the more eective we can be at treatment at an individual level. And when we want to solve the whole epidemic, we need to work on prevention too. If you know how hard it is to lose weight, then you know how important it is to prevent people from becoming overweight and obese.