Significant weight loss improves metabolism, mood, and decision-making in individuals with obesity

Severe obesity not only predisposes individuals to a variety of health risks but also significantly alters their metabolic functions and psychological states. Historically, it was believed that individuals with severe obesity tended to display heightened impulsivity and a greater propensity for risk-taking. However, recent research conducted by scientists at the DZD partner German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE) has explored whether substantial weight loss could reverse these effects, enhancing both metabolic and psychological conditions and thereby improving decision-making processes. These findings have been elucidated in the publication ‘Clinical Nutrition‘.

Human behaviour is influenced by a myriad of factors including personality traits and internal physiological signals like glucose metabolism and mood states. In individuals with obesity, these internal signals are often disrupted, leading to unreliable decision-making foundations. Beatrix Keweloh, a doctoral researcher in the Department of Neuroscience of Decision and Nutrition, spearheaded an intervention study to investigate if these impairments could be reversed through significant weight loss. The study involved 62 participants, aged 18 to 75, all with severe obesity (BMI > 35 kg/m2). They underwent a rigorous 10-week diet limiting their daily caloric intake to 800 kilocalories.

Measurements of participants’ weight, body fat, mood (via a questionnaire), and risk-taking tendencies (using a computer-based test) were taken at both the start and conclusion of the diet. Results demonstrated a considerable decrease in BMI and HbA1c levels—markers of glucose metabolism—and notable improvements in mood. Additionally, there was a shift towards more risk-averse behaviours, suggesting a direct correlation between BMI and risk behaviour in individuals with obesity. “Our findings also indicated that the metabolic factor HbA1c becomes a predominant predictor of risk-taking behaviours post-weight loss,” commented Beatrix Keweloh.

The study further noted that post-weight loss, mood had a diminished impact on decision-making, with metabolic signals becoming the primary influencers of risk behaviour. “Weight loss positively impacts glucose metabolism and mood, and importantly, restores the regulatory function of glucose metabolism in decision-making processes,” Keweloh summarised.

The interplay between weight loss and the metabolic and psychological factors influencing risk-taking is intricate, with BMI playing a pivotal role. A reduced propensity for risk-taking correlates with a healthier lifestyle, crucial for both achieving and maintaining a healthy body weight. Consequently, interventions aimed at managing weight should incorporate both metabolic and psychological considerations to prevent relapses and foster metabolically driven decisions.

“This study is pioneering as it considers both metabolic and psychological aspects in overweight individuals,” stated Prof. Soyoung Q Park, head of the Department of Neuroscience of Decision and Nutrition. “It marks a significant contribution to the field, although it also highlights the necessity for further research to fully comprehend how energy balance and psychological factors influence our choices.”

Globally, the prevalence of obesity is escalating rapidly. According to a report in the British journal ‘Lancet’, over one billion individuals are affected worldwide, out of a global population of approximately eight billion. Data from the Federal Statistical Office reveal that in Germany alone, around 42 percent of women and 62 percent of men are considered to have either overweight or obesity. The World Health Organization (WHO) classifies individuals with a BMI over 25 as having overweight and over 30 as having obesity.

In studies assessing risk-taking tendencies, various methodologies are employed, such as computerised lottery tasks. In this particular study, a conventional lottery task was utilised where participants made choices between a guaranteed monetary amount and a variable amount, with a 50 percent chance of winning in each scenario.