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Rewarding ourselves with food, or eating even when we aren’t hungry, is a major cause of obesity.

Bariatric surgery yields the best results over time for the morbidly obese

Individuals with morbid obesity often reward themselves with food. Recent research shows that dieting is good for changing eating habits and weight. However, bariatric surgery more advantages.

One cause of morbid obesity is that we eat even when we’re not hungry. We do this to satisfy other needs. Often, we want to achieve some kind of short-lived feeling of happiness by rewarding ourselves.

Scientists sometimes call this hedonic hunger.

But we already know that this drive to eat is not good for us, even when we find ourselves peering into the fridge late at night. This continues to be a problem once we have managed to reduce our body weight, because a hedonic appetite can contribute to regaining the weight we lost.

So how can we best counteract a hedonic appetite?

Dieting alone or bariatric surgery

“We wanted to see how hedonic hunger and food reward changed for patients on low-energy diets, and also whether bariatric surgery made any difference,” Marthe Isaksen Aukan says.

She is a PhD candidate at NTNU’s Department of Clinical and Molecular Medicine. The results have now been published in the journal Obesity. Aukan is first author.

Hedonic hunger

The researchers examined two different outcome variables on what they generally term hedonic appetite:

  • The influence of food, so-called hedonic hunger, refers to what we experience when our thoughts, feelings and the desire for food are influenced by signals or signs of palatable food, regardless of our physiological energy needs.
  • Reward, which refers to the impact of palatable food.

The researchers also talked about "liking" and "wanting". Liking refers to whether and how intensely you like a certain food, in a conscious state. Wanting involves the motivation to eat this tasty food, both consciously and unconsciously.

With and without surgery

Obesity is defined as having a body mass index (BMI) of over 30. The participants in this study had an average BMI of over 40 before they started dieting and in some cases also had surgery.

  • Some of the participants in the study managed to reduce their body weight solely with the help of a supervised low-energy diet that lasted more than ten weeks.
  • The other group were put on a low-energy diet two weeks before undergoing some form of bariatric surgery.

Both groups were successful in losing weight when they received help. The researchers found no difference in weight loss between the two groups after ten weeks.

The average weight loss for both groups was 16 per cent of their starting weight.

Both groups also ended up in a state of ketosis. Ketosis results from accumulating residual substances in the blood because fat reserves are broken down when the body receives little sugar. Ketosis reduces or prevents an increase in appetite.

However, the problems often surface in the post-dietary period. This is when you have to maintain your weight and need to get rid of bad habits.

So which group fared best overall?

Both reduced hedonic eating equally

“Participants’ hedonic appetite decreased in the time after dieting, both for those who had surgery and those who didn’t,” Aukan says. “This form of hunger lessened about the same amount for both groups."

It appears that getting professional help to change one's diet can reduce some of the food intake that is not due to physiological hunger.

This finding gives us important insight into how patients who lose weight manage to keep it off.

Aukan notes that it might be necessary for people to receive help for a time after their weight loss, when they are incorporating extensive changes in their dietary habits.

Why bariatric surgery?

Is there any point in having bariatric surgery? For some, the answer is yes because hedonic eating is only part of the problem with losing weight and keeping it off.

Bariatric surgery provides other benefits in terms of rewarding oneself with food and making the right dietary choices, Aukan explains.

The patients who only took the dietary route had little or no change in their food reward behaviour. This contrasted with participants who also underwent some form of bariatric surgery.

Those who had surgery reduced their food reward cravings in all food categories.

“We know that the vast majority of people who lose weight through diet alone are unable to maintain their target weight for very long. Bariatric surgery is the most effective treatment for obesity, and provides greater and longer-lasting weight success,” Aukan says.

Large individual variations

44 patients with morbid obesity completed the study. The researchers pointed out the importance of studying the connections between hedonic hunger, reward in the form of food, and long-term weight loss more closely, where both changes in lifestyle and bariatric surgery are parts of the treatment.

The researchers found wide individual variations and consequently suggested that bariatric surgery is not right for everyone. Options are continuing to open for medical treatment of obesity.

“But we have to find out how the factors are connected, and how we can use this information to provide the best possible and correct treatment for everyone,” Aukan says.


Aukan et al. Changes in hedonic hunger and food reward after a similar weight loss induced by a very low-energy diet or bariatric surgery, Obesity, vol. 30, 2022. DOI: 10.1002/oby.23535

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