Excess weight is the subject of the seventeenth Rotterdam Lecture. The person giving this year’s lecture is none other than Liesbeth van Rossum, Rotterdam specialist. Her book “VET Belangrijk” came out in mid-April. It was a bestseller within a week and the first edition sold out. The book is currently being translated into German, French, Spanish, English and Chinese – among other languages; it’s going round the whole world. “It’s nice to know that the book will come out and be read in many countries, but what really makes it worthwhile for me is the fact that it will enable us to help more people. Mariëtte Boon, co-author, and I are on a real mission with this book. All these figures on excess weight hide real people, who are often extremely unhappy.”

On every street corner in Rotterdam there is a hamburger joint, a pizzeria, a chips shop or other fast-food outlet where you can get nice greasy food. But isn’t this also the case in other cities? Then why are such a large number of Rotterdam’s residents so fat?

“The 2018 figures of Statistics Netherlands show that over half of Dutch people are now overweight, and 15 percent are obese. On average, the percentages in Rotterdam are slightly higher. However, this is also increasingly becoming a problem in the countryside. It’s often thought that this has to do with money, but that’s not the case. Socio-cultural factors also play a role. If you’re in a football team whose players always have a beer after a match, you’re not likely to ask for a glass of water. When Jamie Oliver started to cook free healthy meals in English schools, mothers would pass their children hamburgers through the school gates. The general attitude was: ‘My child’s not going to eat that horrible salad. That would be cruel.’ It therefore doesn’t always have to do with money, but also with socio-cultural factors.”

It’s no coincidence that Alderman Sven de Langen introduced the speaker and her topic. He has declared war on the large number of fast food restaurants in Rotterdam. How important is this step?

“Very important! We’re all keen to reduce obesity and excess weight and we need to take some action. We’re now fighting a never-ending battle. To end the battle, we first need to take preventative measures. If we were not continuously exposed to too much unhealthy food, and if the people around us would encourage us to exercise so that, for example, we would be more likely to take the stairs instead of the lift, or cycle to work, we would be taking important steps.”

“Prevention alone is not enough. Seriously overweight people should also get assistance in the form of a combined lifestyle intervention: healthy food, exercise according to the healthy exercise norm and, in particular, assistance with these behavioural changes. The latter is essential since it is still too often thought that everyone can manage this on their own, which is often not the case. There are many mechanisms that make us choose our food subconsciously. If you eat a treacle tart at 3 p.m. every day for three days in a row, your body will crave a treacle tart on the fourth. It doesn’t take long to become pre-programmed in this way, but it takes a very long time to give up such habits. The changes should really take place in the brain. This assistance takes about two years.”


The book shows that fat is not only an important issue, but also a complex one. It goes way beyond healthy food and regular exercise, though that’s what you hear everywhere.

“I think that’s why the epidemic persists. Due to a lack of knowledge. The fact that we all think: just exercise more, eat less, problem solved. If it were that easy, it wouldn’t be such a problem. If someone is already seriously overweight, so much in his/her body will already have changed so that, for a start, all kinds of substances make it difficult to lose weight. There are also other solutions for this. Prevention is of course also important. Most Dutch people don’t follow the 5-a-Day rule or satisfy the national exercise norm. We can really make some gains here, but we also see that excess weight and even obesity occur in people who lead a healthy lifestyle. There are usually other underlying causes.”

‘Geef internationale studenten niet de schuld van verengelsing’

In an attempt to lose weight, many go on a crash diet…

“I see a lot of people who want to do something about their weight and go on a crash diet. This doesn’t help in the long term, and people get very disappointed. They lose weight at first, but their hunger hormones eventually increase and their satiation hormones decrease. This increases their appetite while their fat combustion decreases (because of their crash diet). They will then have to work even harder to stay at least the same weight. Such a diet is a life sentence, so to speak; they have to fight reduced fat combustion all their life.”

The book includes a lot of personal stories of people who are fat for a variety of reasons, from a congenital insatiable hunger to lack of sleep and extreme stress. Shame plays a role in all these stories. Why did you want to emphasise this?

“We see a lot of unhappy people in our surgery. Most of the new patients I see are in tears, simply because we look at the problem in the widest possible context. Normally you’re just told: ‘You’re overweight, you’d better go on a diet.’ The people who come here will already have tried this. There’s often more involved and when you look very closely, you’ll see the underlying causes for many people. Think of weight-inducing medication, hormonal changes, lack of sleep and stress, for example. It’s often a combination of factors.

“Shame often stops people dealing with excess weight. When an obese person puts on a track suit and goes out in the street to exercise, he or she is not likely to receive compliments. As a society, we’re therefore not very helpful. Thin is the norm. Obesity-based discrimination is the last form of socially accepted discrimination.”

To what extent are stress and excess weight related?

“A great deal. When you feel stressed, your body produces more cortisol, which increases your appetite for snacks and more visceral fat. We know that over half the people with obesity have an increased cortisol level. We are currently studying whether this combination starts off with a high level of cortisol which then leads to obesity or vice versa. It’s a chicken and egg situation. What came first: stress or excess weight? We hope to be able to review this research in a year’s time.”

What’s the biggest challenge when it comes to excess weight?

“To share more knowledge about the problem. This could be achieved through education in schools or by passing on knowledge to doctors. Because we all think too simply, we keep going round in circles and don’t get it right. You can sometimes do something about sleep, stress or medication, and if you want to change your behaviour, you need to take steps here. However, we also need to make sure people understand how temptation works. When you see or think about a treacle tart, your hunger hormone is activated and you produce more saliva. Your insulin and blood sugar levels decrease and you get a craving for something sweet. If you’re aware of this, you won’t give in to temptation so easily. It often happens quite subconsciously.”

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