Weight loss influences risky decisions in obesity

A recent study found that people who are severely overweight (obese) might not only exhibit altered risk behaviours but also changes in their metabolism and psyche.

Scientists at the DZD partner German Institute of Human Nutrition Potsdam-Rehbrucke (DIfE) have now explored whether substantial weight reduction improves metabolic and psychological states, as well as decision-making ability. The findings were reported in the journal Clinical Nutrition.

It was previously assumed that severely obese people could possibly be more impulsive and show an increased willingness to take a risk.

A variety of elements influence our behaviour. On the one hand, it is a reflection of our personality, but it is also influenced by physiological signals like glucose metabolism and mood.

According to studies, these characteristics have a radically different effect on persons who are obese. In this instance, glucose metabolism and mood are affected, thus they no longer give signals that serve as a dependable basis for decision-making.

Beatrix Keweloh, a doctoral student in the Department of Neuroscience of Decision and Nutrition, and her team investigated in an intervention study whether this condition can be reversed by massive weight loss.

They recruited 62 test subjects aged between 18 and 75 with severe obesity (BMI > 35 kg/m2) and prescribed them an intensive 10-week diet with a daily energy intake of 800 kilocalories.

At the beginning and end of the intervention, the participants' weight and body fat were measured, their mood was recorded using a questionnaire and their willingness to take a risk was determined using a computer-based test.

Role of the long-term sugar level HbA1c: As expected, after the 10-week diet there was a significant reduction in the body mass index (BMI) and the HbA1c level as a marker for glucose metabolism, as well as a significant improvement in mood.

In addition, the scientists were able to demonstrate a positive change in behavior, as the weight loss led to risk-avoiding decisions. Accordingly, risk behavior in obesity appears to be highly dependent on the BMI.

"Our results have also shown that the metabolic factor HbA1c becomes the leading predictor of risk-taking after weight loss," says first author Beatrix Keweloh.

The study also showed that mood loses its influence on decision-making after weight loss. The participants' risk behavior was therefore more strongly influenced by metabolic signals than by emotional ones.

"We have shown that weight loss has a positive effect on glucose metabolism and mood and, in particular, that it is possible to restore the function of glucose metabolism as a control signal," summarizes Keweloh.