Personalized diets

Reading time: 3 minutes


BY Hanny Roskamp | PHOTOGRAPHY Marije Kuiper

November 2018

New research aims to show how diets can be personalized. This can help against a range of obesity-related diseases.

People react differently to foods. We are all different; it’s as simple as that. Not everybody is equally resilient, and not everybody recovers equally fast from an excess of fat and sugar. That might sound obvious but scientists have only recently begun to understand how it is possible and, especially, how it works.

In 2015, Israeli researchers Segal published research that showed how sushi and ice cream created a massive glucose peak in some people and a much lower one in others. They also discovered that this reaction can be predicted by analysing the bacteria in their guts (intestinal flora).

Predicting reactions to nutrition

This was a complex study, in which the blood sugar levels of hundreds of test subjects were measured as they reacted to a lot of different foodstuffs. All the data were then correlated with the composition of their intestinal flora. Fast computers can spot patterns in a mountain of data of this kind. And that provided information that allows glucose reactions to food to be predicted for individuals by testing a faecal sample.

Test subjects had their body fat distribution measured with a DEXA scan.

Lydia Afman, associate professor of Human Molecular Nutrition, studies the reactions of individuals to food. And she too has noticed that these reactions can vary enormously. After a big dose of sugar (a ‘sugar challenge’), some people’s blood sugar shoots up, while in others it stays within manageable limits.

If the blood sugar stays reasonably stable, the hormone insulin (whose functions include sending sugar to the muscles and fatty tissues) can work well. If the blood sugar gets out of hand, the functioning of insulin is disturbed and that is a sign that the person could get type 2 diabetes in the future.

‘It is becoming clearer and clearer that what’s good for me is not necessarily good for you’

In general, people who are overweight more often have a disturbed sugar metabolism, and a greater risk of type 2 diabetes. Nevertheless, in her research, Afman saw overweight people whose blood sugars didn’t go up excessively when they took part in a sugar and fat challenge. “So it is becoming increasingly clear that what’s good for me isn’t necessarily good for you. Each body reacts differently, and there isn’t just one trend.”

The test subjects had blood tests before, while and after drinking a shake. The butter and sugar lumps show how much sugar and fat the shake contained. On the right is a meter than measures glucose continuously.


Lydia Afman PhD


Associate professor of Human Molecular Nutrition at Wageningen University & Research

Resilience research

Research on personalized diets that help bodies get their resilience back and recover


Lydia Afman works on this research with scientists from the Top Institute Food & Nutrition (TiFN)

Lydia Afman thinks the Israeli study has not uncovered the whole story. That is why she is working on a follow-up study. “I think their study was great: it opened up new territory, and as a result we can take it a step further. In the next two years, we are going to work with the University of Maastricht on a study based on the idea that the composition of a diet for optimal health differs per person. Participants will follow dietary advice for a period. In some cases, this will focus mainly on healthy fats, and in others on proteins and nutritional fibre. People can still sign up for the study (which is conducted in Dutch).”

‘An ice cream causes a massive glucose peak for one person and a far lower one for another’

Her research is highly relevant today. It looks at overweight and obesity, problems that more and more people are suffering from: more than 50 percent of the Dutch population. What is more, overweight can precede more serious ailments such as cardiovascular disease, cancer and type 2 diabetes.

Preventing premature death

In future, Afman hopes her research will produce specific guidelines for people with overweight. Personalized ones, at that. “Does the person react positively to healthy fats, or to proteins and nutritional fibre? Once we know that, we can give people tailor-made dietary advice. Hopefully that will motivate them to stick to it, and then we can prevent them falling ill and dying prematurely.”

Lydia Afman: “Each body reacts differently to sugar and fat, and there isn’t just one trend.”

The study shows how resilient the body is. In other words, how far off balance it gets, and how quickly it recovers from a blow which knocks it off balance. “If the body has an excessively high glucose response, and does not recover fast from a sugar challenge, this can be a predictor of problems in the long term, such as type 2 diabetes. But that doesn’t happen very easily.

“The body is remarkably resilient; Even when a person has type 2 diabetes, with the right lifestyle it is sometimes possible for them to return to full health. So ultimately, our research is about the resilience of the body too.”

More resilience stories:

Nothing so resilient as a microbiome

‘Nature is extraordinarily