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Best predictor of sustained weight-loss? Prefrontal cortex activation

Fig­ure 3. Weight Loss at Month 1 Cor­re­lat­ed with Changes in BOLD in Regions Asso­ci­at­ed with Cog­ni­tive Con­trol. Cred­it: Selin Neselil­er et al

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New research sug­gests that high­er-lev­el brain func­tions have a major role in los­ing weight. In a study among 24 par­tic­i­pants at a weight-loss clin­ic, those who achieved great­est suc­cess in terms of weight loss demon­strat­ed more activ­i­ty in the brain regions of the lat­er­al pre­frontal cor­tex asso­ci­at­ed with self-con­trol.

What we found is that in humans, the con­trol of body weight is depen­dent large­ly on the areas of the brain involved in self-con­trol and self-reg­u­la­tion,” says Alain Dagher of the Mon­tre­al Neu­ro­log­i­cal Insti­tute and Hos­pi­tal in Cana­da. “That area of the brain has the abil­i­ty to take into account long-term infor­ma­tion, such as the desire to be healthy, in order to con­trol imme­di­ate desires.”

To assess the roles hor­mones and self-con­trol have in achiev­ing weight loss, the researchers stud­ied 24 sub­jects from a weight-loss clin­ic. Pri­or to start­ing a stan­dard 1,200 kcal/day weight-loss diet, all par­tic­i­pants received a func­tion­al MRI study (fMRI) of the brain, which assessed regions includ­ing the lat­er­al pre­frontal cor­tex, which is linked with self-reg­u­la­tion, and the ven­tral medi­al pre­frontal cor­tex, a brain area involved in moti­va­tion, desire, and val­ue.

Sub­jects were shown pic­tures of appe­tiz­ing foods as well as con­trol pic­tures of scenery. The researchers com­pared the brain activ­i­ty response to the food pic­tures, par­tic­u­lar­ly the high-calo­rie food pic­tures, for each sub­ject at base­line, one month, and three months. “When we show pic­tures of appe­tiz­ing foods, the ven­tral medi­al pre­frontal cor­tex area becomes more active on fMRI,” Dagher says.

Dur­ing the study, researchers not­ed that at one month and three months, the sig­nal from the ven­tral pre­frontal cor­tex went down, and it declined the most in peo­ple who were more suc­cess­ful at los­ing weight. Addi­tion­al­ly, the lat­er­al pre­frontal cor­tex sig­nal involved in self-con­trol increased through­out the study.

In the fMRI, the self-con­trol area increased its activ­i­ty and the val­ue area decreased its activ­i­ty,” says Dagher. “And the amount of change was pre­dic­tive of suc­cess­ful weight loss.” While all par­tic­i­pants lost weight, those who achieved the great­est weight loss had fMRI lev­els indi­cat­ing a bet­ter abil­i­ty to self-con­trol. And, at the end of the 3-month study, the hor­mones ghre­lin and lep­tin were start­ing to return to base­line, sug­gest­ing that a new set point was achieved.

These results sug­gest that weight loss treat­ments that increase self-con­trol, such as cog­ni­tive behav­ioral ther­a­py, may be help­ful, par­tic­u­lar­ly when stress is involved in lead­ing to overeat­ing,” he says. “Stress dis­rupts the lat­er­al pre­frontal cor­tex con­trol mech­a­nism, but you may be able train peo­ple to seek a dif­fer­ent strat­e­gy.”

The Study:

Neu­rocog­ni­tive and Hor­mon­al Cor­re­lates of Vol­un­tary Weight Loss in Humans (Cell Metab­o­lism)

Sum­ma­ry: Insuf­fi­cient respons­es to hypocaloric diets have been attrib­uted to hor­mon­al adap­ta­tions that over­ride self-con­trol of food intake. We test­ed this hypoth­e­sis by mea­sur­ing cir­cu­lat­ing ener­gy-bal­ance hor­mones and brain func­tion­al mag­net­ic res­o­nance imag­ing reac­tiv­i­ty to food cues in 24 overweight/obese par­tic­i­pants before, and 1 and 3 months after start­ing a calo­rie restric­tion diet. Increased activ­i­ty and func­tion­al con­nec­tiv­i­ty in pre­frontal regions at month 1 cor­re­lat­ed with weight loss at months 1 and 3. Weight loss was also cor­re­lat­ed with increased plas­ma ghre­lin and decreased lep­tin, and these changes were asso­ci­at­ed with food cue reac­tiv­i­ty in reward-relat­ed brain regions. How­ev­er, the reduc­tion in lep­tin did not coun­ter­act weight loss; indeed, it was cor­re­lat­ed with fur­ther weight loss at month 3. Acti­va­tion in pre­frontal regions asso­ci­at­ed with self-con­trol could con­tribute to suc­cess­ful weight loss and main­te­nance. This work sup­ports the role of high­er-lev­el cog­ni­tive brain func­tion in body-weight reg­u­la­tion in humans.

The Study in Context:

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