04 Dec, 2020
JERUSALEM WEATHER

Most people who are overweight manage to lose a few kilos but are dismayed by gaining them back. “Yo-yo diets” in which weight is lost and regained are very frustrating and unhealthful. Everyone is looking for that weight loss program that will shed those unwanted kilos and keep them off.

But what if you could undergo a functional MRI (fMRI) scan that would tell you whether a weight loss program was likely to be effective? Researchers at Ben-Gurion University (BGU) of the Negev in Beersheba have discovered for the first time a neural sub-network that corresponds to the gastric basal electric frequency and whose patterns of connectivity predict future weight loss.

Their findings were just published in the journal NeuroImage under the title “Neural correlates of future weight loss reveal a possible role for brain-gastric interactions.” The researchers said their results could advance the understanding of the causes of obesity and the mechanism of response to dieting.

Their conclusions support a prevalent neural theory of impaired weight regulation and over-sensitivity to palatable food cues — that people with an increased neural response to seeing and smelling food consistently overeat and gain weight.

The multidisciplinary team approached the problem from both brain and body aspects. 

“To our surprise, we discovered that while higher executive functions – as measured behaviorally – were dominant factors in weight loss, this was not reflected in patterns of brain connectivity,” explained Gidon Levakov, a graduate student who led the study from BGU’s department of brain and cognitive sciences. “Consequently, we found that weight loss is not merely a matter of willpower but is actually connected to much more basic visual and olfactory cues.”

The researchers identified a connection between weight loss and basal electric rhythm that rhythm governs the gastric waves connected with hunger and fullness. They also found that the brain’s pericalcarine sulcus – the anatomical location of the primary visual cortex that is the primary cortical region of the brain that receives, integrates and processes visual information relayed from the retina of the eye – was the most active node in this subnetwork.

The team assessed 92 people during an 18-month lifestyle weight-loss intervention, entitled DIRECT-PLUS and led by Prof. Iris Shai of BGU’s epidemiology department who is well-known for her long-term dietary intervention studies conducted at the Negev Nuclear Research Center in Dimona. The participants were selected based on large waist circumference, abnormal blood lipid levels and their age.

Before the intervention, the participants underwent a battery of brain imaging scans and behavioral executive function tests. The participants’ weight loss was measured after six months of dieting, in which, according to Shai, the maximum weight loss is generally achieved. he team found that the subnetwork of brain regions corresponded more closely to basic sensory and motor regions rather than higher, multi-modal regions.

“It appears that visual information may be an important factor triggering eating,” concluded principal investigator Prof. Galia Avidan of BGU’s departments of brain and cognitive sciences and psychology. “This is reasonable, given that vision is the primary sense in humans.”