The effects of exercise on the neuronal response to food cues

Abstract

Increased physical activity is associated with successful long-term weight loss maintenance due to mechanisms likely more complex than simply increased energy expenditure. The impact of physical activity on the central regulation of food intake may be an important mechanism of this effect. The objective of this study was to examine the effects of exercise training and acute exercise on the neuronal response to food cues as well as eating behaviors. fMRI was performed in the fasted state at baseline and again after a 6month progressive exercise intervention (supervised, 5 days/wk) both with and without an acute exercise bout in 12 overweight/obese (5 women, 7 men; BMI 33±4 kg/m2) healthy adults. fMRI data were acquired while subjects were presented with visual stimuli of foods of high hedonic value as compared to neutral control objects. Questionnaires on eating behaviors, ratings of appeal and desire for foods, and ratings of appetite (hunger, satiety, prospective intake) using visual analog scales were also performed at baseline and again after the 6-month exercise intervention. While only a trend was observed for a reduction in body weight (102±5 to 99±6 kg, p=0.09), a significant reduction in fat mass was observed (36.4±2.8 to 33.7±3.2 kg, p=0.04), although as expected changes in fat mass were variable (−10.0 to +3.7 kg). Chronic exercise was associated with a reduction in the neuronal response to food, primarily in the posterior attention network and insula. A significant positive correlation between change in fat/body mass and change in insula response to food cues with chronic exercise was observed. An acute exercise bout attenuated the effects of chronic exercise. The exercise intervention, however, did not impact any of the measures of appetitive behavior. In summary, despite no effects on behavioral measures of appetite, chronic exercise training was associated with attenuation in the response to visual food cues in brain regions known to be important in food intake regulation. The insula, in particular, appears to play an important role in potential exercise-induced weight loss and weight loss maintenance.

Exercise and Weight Loss: What Is the Evidence of Sex Differences?

“…We found that aerobic exercise, compared to the rest condition, reduced the neuronal response in food reward (i.e., insula, orbitofrontal cortex, putamen, rolandic operculum) and visual attention (i.e., inferior and middle occipital gyrus) brain regions. This is consistent with a recent study [61] showing that chronic exercise (40-60 minutes/day for 6 months) lowered the neuronal response in the insula (food reward region) in overweight/obese individuals. Thus, these data suggest that both acute and chronic aerobic exercise reduces neuronal responses in food reward and visual attention brain regions, consistent with reducing the pleasure and palatability of food, incentive motivation to eat, and anticipation and consumption of food In exploratory analyses (unpublished observation), we recently assessed exercise-induced changes in neuronal responses in men and women analyzed separately.…”

Elevated energy intake is correlated with hyperresponsivity in attentional, gustatory, and reward brain regions while anticipating palatable food receipt

“…In support of the current results, increases in fat mass over a 6-mo period were associated with increases in responsivity to palatable food images in visual processing/attention and gustatory regions relative to baseline (39). In addition, behavioral data indicated that individuals randomly assigned to consume energydense foods for 2-3-wk periods showed an increased willingness to work (ie, incentive for those foods) (40,41).…”

Acute and Chronic Effects of Exercise on Appetite, Energy Intake and Appetite-Related Hormones: the Modulating Effect of Adiposity, Sex and Habitual Physical Activity

“…Some studies have shown that subjective appetite in the fasted state is increased after exercise training [40][41][42], whereas others have reported no change [43][44][45] or even a reduction in appetite [46]. Furthermore, exercise training has been shown in some studies to have negligible effects on energy or macronutrient consumption [9,43,47,48], while others have demonstrated that energy intake is reduced [49] and protein intake is elevated [45] after training.…”