Flexible dieters are more successful dieters: weight regain and the tendency to think in black and white terms

Maintenance of a healthy body weight is challenging for many people. Diet success rates are generally low and it has been shown that 50% of the weight loss is usually regained after one year. 

A factor that has been associated with overeating and weight regain is thinking in black and white terms; a personality trait that is called dichotomous thinking. People often hold divided beliefs about food (healthy or unhealthy), their diets (on track or out of track), but also about their weight (acceptable or unacceptable) and these beliefs may lead them to overeating when they have the feeling that they have violated their diet.  

Katerina Palascha

For her Master thesis project, Katerina Palascha conducted a survey among 241 adults. She wrote a paper about the study and recently this paper was published  in Journal of Health Psychology. Quite an achievement!

The study revealed that the greater the self-initiated attempt to control food intake (dietary restraint) the higher the weight regain. However, it was the dichotomous thinking rather than dietary restraint that really predicted weight regain. This implies that when the attempt to control intake is accompanied by a rigid ‘black and white thinking’ style, people’s ability to control their food intake may be inhibited, thus leading to weight regain. In line with this finding, a study of Sairanen and colleagues showed that adopting a more flexible self-restrictive eating behaviour (as opposed to rigid self-restriction) could lead to a better weight loss maintenance and well-being.

Katerina's study again showed the importance of avoiding the 'what the hell' effect. Do not think: 'I have already ruined my diet for today, why not even indulge more..!'. Flexible dieters are more successful dieters.

The dining table should be more than just a place for eating

A study of Brian Wansink and myself as co-author was published recently. The study shows that the dining environment itself is associated with weight status. It was picked up by several newspapers, such as the Los Angeles Times ('Mealtime rituals might make a difference in obesity, researchers say') and the Daily Mail Online ('Telly tubbies: Eating dinner in front of the TV 'makes you fatter than sharing a meal with family at the table').

Read the Cornell University's Press Release:

'Beyond plate size and calorie and carbohydrate counts, the war against obesity may have a better front – the dinner table. Eating dinner with kin (and without the TV on) is linked to lower body mass, reports a Cornell behavioral economist in the journal Obesity.

Families that eat together frequently – and stay seated at the table until everyone’s finished – have children with lower weights and Body Mass Index (BMI). This is especially strong with boys. Strong, positive socialization skills that dinners foster possibly supplant the need to overeat, explain the researchers. Mothers and fathers who talk meaningfully with children about their day at the dinner table also have lower BMIs.

“The ritual of where one eats and how long one eats seems to be the largest driver,” said Brian Wansink, professor in Cornell’s Dyson School of Applied Economics and Management and director of the Cornell Food and Brand Lab. He co-authored the study with Ellen Van Kleef, assistant professor at Wagening University, the Netherlands.

But families that eat dinner while watching television can turn chubby, as the researchers linked that to higher BMIs. “In fact, eating anywhere other than the kitchen or dining room was related to higher BMIs in both parents and in children,” said Wansink.

“By focusing on family dining rituals, this research departs from the more food-centric approaches. Dinner starts with meal preparation, and while being involved in meal preparation was unrelated to the BMI of young boys, it was positively correlated with the index of young girls,” said Wansink.

“Family meals and their rituals might be an underappreciated battleground to fight obesity.”

The study, “Dinner Rituals that Correlate with Child and Adult BMI,” was published online in Obesity, Oct. 1, and was funded by the Cornell Food and Brand Lab.'

A nudge that did not work: a virtual supermarket study among children to promote healthier snacking

Nudging consumers towards healthier food choices is still a hot topic. Drawing on psychology and behavioural economics, nudges are simple intervention strategies to move consumers towards healthier choices. This is done without banning foods products or telling consumers what to eat or avoid.

There are quite a few examples of successful nudges that help consumers in making better food choices. For instance, if consumers were asked to downsize their side dish, they ended up eating less in the study of Schwartz and colleagues. Still, there is a lot of debate about the usefulness of nudging. Consumers need more than a nudge, is the argument put forward by Lucy Handley. Lord Krebs recently argued in the Guardian that nudging alone will not convince people to do important things like lose weight. They both might be right, but at the same time I think it very useful to collect empirical evidence on the effectiveness of nudging.

Last Summer, we carried out a nudge study among 113 primary school children (10-12 years old) to encourage them to go for a healthier snack. We were inspired by the proven marketing tactic to offer a free gift with purchase (think of McDonald's Happy Meal). Typically, children are confronted with these free gifts on energy dense snacks. But would it be effective to use this classic marketing tactic to encourage children to switch to something healthier? That was the key question in our virtual supermarket study on which Charlotte Petri graduated last August.

We asked children to do some groceries in the virtual supermarket and select their own snack and drink near the checkout counter. This simulated supermarket of Wageningen University looks like a real supermarket with various shelves which display three-dimensional images of a wide range of products. The children could walk through the aisles of the store and put products in their virtual shopping cart.

Participant chooses a snack in the virtual supermarket

Participants did not see the same snack shelf, however. One third of all participants were confronted with a shelf poster that promised them a free gift (a tattoo) when they would buy a product with a star. These 'star products' were all healthier options as indicated by the Dutch Nutrition Centre. Another group were similarly promised the same gift, but now the star was attached to relative unhealthy snacks. The third group was the control group who did not get to see any promise of a free gift.

Snack shelf with poster promising free tatto gift with healthy 'Star' purchase

Most children were very enthusiastic about 'shopping' in the virtual supermarket ('Where can I download this game?'). Less than half of all children selected a healthy snack and drink. They were, however, not influenced by the promised free gift, regardless of the type of product to which the star was attached. It could be that the gift was not attractive enough, although a pre-test indicated differently. Another explanation is that children might have been too focused on the shopping task. In other words, they were too 'busy 'walking' through the shop, impressed by the new experience.

About one fifth of all participants was overweight. This percentage is similar to the percentage Dutch children who is overweight. Although overweight children more often tended to go for unhealthy snacks, they were not more sensitive to the free gift than normal-weight children. Children chose snacks based on familiarity and preference. Health was less important in their choice.

Overall, although the nudge was not effective in its present form, we learned a lot about the possibilities of the virtual supermarket for choice experiments with children. Have a look at the video, in which a participant walks through the supermarket and makes her snack choice.

Watch 3-year-old Lukas grazing snacks all day: A confronting Dutch childhood obesity awareness campaign

'Also happy with this environment?' is the question posed by the Dutch Nutrition Center in their new campaign. The video of this campaign is definitely worth watching.

Many children have poor eating habits which may lead to overweight and obesity. Children are constantly bombarded with unhealthy, high-caloric snacks and meals. As a result, children nowadays live in a so-called 'toxic food environment', a term invented by obesity researcher Kelly Brownell. 

Successful obesity awareness campaigns require careful consideration of the target group and a key relevant message. On the one hand, they need to make parents aware of the seriousness of the problem. On the other hand, they need to provide useful information and not stigmatize or shame overweight children. This is not simple, as shown by a failed and controversial US childhood obesity campaign.

I particularly like the final scene of the video in which Lukas refuses the healthy meal cooked by his parents. It is a very familiar scene for many parents, including myself. Have a look yourself!

3 surprising insights on how food cravings relate to other desires in everyday life

What is harder to resist? Checking your Twitter or Facebook account at work or eating a delicious, but fattening snack when you try to watch your calories? Both are inner conflicts, best described as 'I really want to do this, but I should not'.

In many food studies it is assumed that people have conflicting feelings when being confronted with tempting foods. But is that really the case in everyday life? What type of cravings are felt most strongly? And if people do crave foods, how often are they trying to resist their desire?

Wilhelm Hofmann, Kathlees Vohs and Roy Baummeister recently tried to answer these questions in their Everyday Temptation Study. They gave BlackBerrys to 205 participants and contacted them on 7 random times per day for one week. When they were contacted, they had to indicate what type of desire they experienced within the last 30 minutes, how conflicted they felt about this desire, whether they tried to resist the desire and how successful they were in this. The study included all types of everyday desires, including the desire to eat, drink, have sex, sleep, spend money and use media (such as social media). Here are 3 insights that I found most surprising.

1)   Food is not the hardest desire to resist
People feel some desire about half the time they are awake. In hours, this is about eight hours a day. Almost half of those desires are conflicting at least somewhat with other goals in life.
Interestingly, food is not the hardest desire to resist. It is much more difficult to fight the desire for sleep and fun leisure activitities (such as checking Facebook). These two were considered to be the hardest to resist. Only 23% of all conflicting desires go against some health goals (for example healthy eating or exercise). The majority of reported inner conflicts were related to goals such as saving money, achievements at work or study, social appearance and efficient time use.

In other words, it is harder to resist impulses to spend money, participate in sports, use (social) media and smoke than it is to resist eating.

2)   We spend three hours a day resisting desires
The majority of desires in everyday life are not resisted. We have to eat anyway, so why trying to resist it? When people do try to resist them, they are quite successful in it; in 83% of all inner conflicts, they succeed to not give in. Still, in 17% of all occasions, people do give in. They particularly fail to resist checking e-mail, Facebook, Twitter of other social media when they do not want to do that.

3)   Stop resisting the numerous cravings throughout a day
Besides that we spend about three hours per day resisting desires, we also spend half an hour giving in to desires that we initially resisted. The more often you try to resist a desire, the less willpower is left at the end of the day and the more likely it is that you go for the 'forbidden' food. This confirms the 'muscle model' of willpower, which states that willpower is like a muscle that needs refuel.

So, do not replete your willpower, stop reading this blog post and go back to work.



What is harder to resist; Twitter and Facebook at work or the temptation of an unhealthy snack?

Hofmann W, Baumeister RF, Förster G, & Vohs KD (2012). Everyday temptations: an experience sampling study of desire, conflict, and self-control. Journal of personality and social psychology, 102 (6), 1318-35 PMID: 22149456

Dealing with Big Food: Slow public health response to large food companies' influence

Recently, the world population exceeded 7 billion people. One billion of them is hungry, while at the same time two billion are overweight. This shows we have a huge problem in meeting people's dietary needs. As what people eat is increasingly determined by a few multinational food and beverage companies, this month a new series of articles on the influence of these companies ('Big Food') will appear in PLOS Medicine Magazine. Highly recommendable!

David Stuckler and Marion Nestle start off with their essay on Big Food's problematic influence on the global food system. The authors cite research that shows that the ten largest food companies control over half of all food sales in the United States. Unfortunately, what they successfully sell consists primarily of processed foods enriched in sugar, salt and fat. Frequent consumption of these foods is associated with excess weight and chronic diseases.

The decades-long fight against tobacco has provided us with insights on typical tactics used by industry to undermine public health measures such as taxation and regulation, they state. Basically, that is because food companies aim to maximize profits and not health. They do not like interventions that threaten their profits.

Public health professionals are slow in responding to the threat of Big Food and the authors therefore urge for more strong and conscious choices about how to deal with Big Food's influence. Dealing with the food industry involves more than partnering or waiting for self-regulatory initiatives. It requires a critical approach, recognizing the conflicts of interests that play a key role.

Stuckler and Nestle conclude by stating 'without taking direct and concerted action to expose and regulate the vested interests of Big Food, epidemics of poverty, hunger, and obesity are likely to become more acute'.  A strong plea for action...

Is there hope for a thinner future?

There is not much progress made in combatting the overweight and obesity epidemic. That is a conclusion drawn in a recent paper of the prominent researchers Peter Herman and Janet Polivy: 'Self-regulation and the obesity epidemic' (Social Issues and Policy Review).  I found it an inspiring paper. Both authors are highly influential and experienced in the field of experimental psychology of eating behaviour and obesity. Because of their outstanding track record, I recommend reading their paper and think about it. Their take home message is not a positive one, however.   

Picture: Rudd Center Image Gallery



The basic premise of the article of Herman and Polivy is that researchers should be sceptical about interventions, both at the individual and societal level. They state that many researchers suggest that progress is being made or just around the corner. But actually, this is not true. Their review of the literature coupled with the decades of  professional experience made them conclude the following: ‘Scrutiny of the statistics, however, suggest that not much progress has been made so far in combatting the problem; in fact, it is probably easier to make the case that things are continuing to get worse’.

The best interventions at an individual level (e.g. clinical interventions) are expensive or impossible to implement on a community-wide basis. Although the authors agree with many scientists that interventions at a societal level (e.g. reshaping of the environment) are needed, they are not optimistic. Basically, many ideas for interventions will not work or even backfire, they argue.



Obesity is a very serious problem. Herman and Polivy stress that it not ok to implement unproven interventions. They warn that scientists should be cautious about applying solutions that turn out to be ineffective as the little trust that the public has in social scientists should not be destroyed.

What do you think? Is there really not much progress made? Is there hope for a thinner future?

The Oprah Paradox: why people with excellent self-discipline also have a hard time controlling their body weight

Willpower has typically been looked at as a trait that one has or has not. For decades, self-esteem was the concept that needed to be promoted while self-control was viewed as old-fashioned. But willpower is back in fashion as research has shown that it is a key positive factor predicting happiness and well-being.

I just finished reading the book 'Willpower' of Roy Baumeister and John Tierney (In Dutch: Wilskracht: De herontdekking van de grootste kracht van de mens). Roy Baumeister is a leading scientist in the field of willpower and self regulation and became widely known for the process of 'ego depletion'. Having too many choices will exhausten your self-control as we draw on the same source of willpower for various tasks, not just related tasks. That means that willpower is like a muscle which needs to be fuelled by sleep and food (glucose).

Wilskracht - Baumeister & Tierney

In chapter 10, Baumeister and Tierney discuss what they label the 'Oprah Paradox'. Oprah Winfrey must have had excellent self-discipline and willpower to achieve the success that she did. Nevertheless, even she has a hard time to consistently control her weight. The authors discuss this paradox by listing some reasons why dieters fail. In order not to eat, a dieter needs willpower. Willpower runs on glucose. So, to fuel willpower, a dieter needs to eat. In other words, dieters deprive themselves from what they need the most. Another big threat is that dieters often fall for the so-called 'what the hell effect'. A small slip in their diet will make them blow off the dieting rules entirely. Dieting is obviously not the solution. The authors argue for small manageble changes. Over time, these small changes will become habits and having good habits saves willpower.

Overall, this is a book absolutely worth reading as it clearly shows how important willpower is. In an entertaining way the authors offer advice on how to strengthen self-control and use willpower wisely. One of them is: never say never when it comes to dealing with tempting foods. It is better to tell yourself to eat a small portion later than forbid yourself to eat them at all. This postponement method allows the impulse to fade away and in this way encourages self-control.

My Top 3 of free apps that support you in sticking to your goals

We all know that it is very hard to stick to your goals. Here you find my Top 3 of free apps that help you stick to your New Year's resolutions.

1) The Eatery: Build on the honest real-time feedback of friends and strangers

My favorite one! Self-monitoring improves self-awareness of behaviour ('Am I really eating that much chocolate?'), but writing down everything you eat can also be quite boring and time-consuming. The Eatery promotes its free app with the slogan 'stop counting calories, start eating better'.

The idea is that you take a picture of everything that you plan to eat. Then you invite your friends to comment on the meals you are about to eat or just finished. Within a few minutes you will then receive a rating on a scale of 1 (very unhealthy) till 100 (extremely healthy). As you can see, my homemade oliebollen (Dutch treat) were not considered to be very healthy. I did not connect to Facebook, but still I received about 20 ratings per snapped food. So, by using crowdsourcing, other people evaluate the healthiness of your eating habits. 

This app is addictive and fun to do! However, I do not always agree with the crowd's healthiness ratings. I noticed that the crowd is also susceptible to biases such as health halos and the negative calorie illusion. Just put a salad next to your burger or state that it is fat-free, and the ratings go up substantially. And although you can indicate the portion size consumed, I have the impression that you do not include that information in your ratings of other people's food. But the idea is great and offers opportunities for interesting consumer studies.

2) Stickk: Make yourself accountable; pay when you do not reach your goals

Stickk is not an app, but a site that claims that your chances of success are higher when you put actual money on your goal. It is not obligatory, but you have the option to commit money to your goal and if you do not achieve it, Stickk will send the money to the person, charity or organisation that you indicated. The site is founded by Yale economists and based on two key principles of behavioural economics: (1) people do not always follow up what they intend to do and (2) incentives motivate people to do things. I did not commit money to my goal, so I guess that is the reason that it was not that motivating. I think I am going to commit myself again, but then with serious money....

3) My Weight App and MyNetDairy: track your weight loss progress
A recent study of Barbara Cunningham showed that people do not lose more weight when they track their diet using smart phones compared to the traditional pen and paper method. But still, if you have a smartphone, it is convenient to try an app.

These apps help you to track you weight day by day (My Weight App) and calories/exercise (MyNetDiary). I used the free versions, and they are easy to use. The progress bar of the My Weight app gives a view on how far you progressed with your weight loss.

Do increased serving bowl sizes influence how much we eat?

It is often stated that that the increasing size of food portions is a strong factor contributing to the incidence of overweight and obesity. Numerous studies have shown it again and again: larger portion sizes, serving devices and packages lead people to eat more, often without them realizing it. In particular, individual serving devices such as plates, spoons and bowl have been shown to influence food intake. However, what has not been shown is whether the most central focus of the dinner table, the main serving bowl, has a similar magnifying effect. When one is eating at home and eating out in buffet restaurants, food is often available in serving bowls from which individual portions are distributed.

This month, the paper 'Serving bowl biases the amount of food served' I wrote together with Mitsuru Shimizu and Brian Wansink came out in the Journal of Nutrition Education and Behavior. This paper reports our study in which we wanted to determine how serving bowls filled with food for many persons influence serving behaviour and consumption. We expected that the larger the size of a multiple-serving bowl, the more people will serve and consume. In the study, 68 participants were randomly assigned to a group serving pasta from a large-sized bowl (almost 7 litre capacity) or a medium-sized bowl (almost 4 litre capacity). When given a large bowl, diners served 77% more pasta compared with the diners serving from the medium-sized bowl. They ate more, even though the food was not rated tastier or otherwise notable different.


Bowl size matters, so fill your largest bowl with salad



We wondered about the reasons for our findings. It could be that more 'social' reasons inhibit an individual from taking too much food from a smaller common bowl. Perhaps people use the size of serving bowl filled with food for multiple persons as an indication of how much they can best serve themselves. It could even seem greedy to take more food from a smaller bowl.

In any case, small increases in food intake may lead to substantial additional caloric intake over a longer time period and even weight gain. Just like larger package sizes, large serving devices seem to suggest to people that large portions are appropriate to consume.

These findings again highlight the role that external cues play in food consumption and show the importance of considering serving bowl size in nutrition education. Maybe our findings can be used to turn bad habits around; just put your salad in bigger bowls.

The six reasons why overweight is a wicked problem

No quick fixes and simple solutions. That is the case with the current overweight and obesity epidemic. You can read this important message in the recently published book 'Tegenwicht. Feiten en fabels over overgewicht', written by Jaap Seidell and Jutka Halbertstadt. The translation of this Dutch title would be something like 'Counterweight. Facts and myths about overweight'.

I really liked reading this book, because it describes in easy-to-read and understandable language the current state of the scientific knowledge on overweight and obesity. What struck me most was that science has not yet come that far in understanding how various factors interact in creating the overweight problem and providing effective solutions. A key reason for that, Seidell argues, is that overweight is a wicked problem. This term was first mentioned in relation to the highly complex problems of social planning, but it can also be applied to overweight and obesity.

Basically, there are six reasons why overweight is a wicked problem:

Reason 1: You know what the problem is, when you have the solution. Since it is hard to define what exactly the problem is, it is difficult to find a solution. This definitely applies to overweight. For example, experts often disagree what the major causes are of overweight: lack of physical activity or overeating? Bad genes or bad eating habits?

Reason 2: The solution process does not have a clear end-point. As Seidell wonders; it is not exactly clear what the purpose is of preventing overweight: halting the rising trends or reducing the number of people with overweight to zero?

Reason 3: Solutions are not right or wrong. All involved stakeholders (such as food companies, authorities, consumers, health professionals) have an opinion about the problem and often disagree. For example, last week we had the No Diet Day (or 'Anti-Diet-day' in the Netherlands). Although the day aims at body weight acceptance, it led to debates about the usefulness of particular diets and the risks of overweight. 

Reason 4: Each wicked problem is unique and new. The involved actors and concrete situations are different. The causes and potential solutions are similarly not the same for different groups of overweight individuals.

Reason 5:  There is no room to experiment. It is impossible to check beforehand whether a particular solution will be effective. Essentially, it is often a matter of critically informed trial and error.

Reason 6: There is no clear set of solutions and there can be many solutions or only one. Solutions are hard to find. As a result, Seidell argues that the overweight and obesity problem requires a holistic solution. For example, schools, food industry, health authorities and consumers should work together in exploring solutions that seem promising. After all, there is a lot at stake: overweight is not just a medical problem, but also a social one. 

Trish Groves likewise argues in the British Medical Journal that obesity seems to be the classic example of a wicked problem. Consequently, we need more innovative and collaborative approaches. I completely agree. Acknowledging that overweight is a wicked problem might help getting a more realistic overview of the problem instead of over-simplistic and one-sided analyses and claims for solutions. It also shows that as researchers we should look across the boundaries of traditional research fields and become more creative in contributing to the search for solutions.