Fasting biases brain reward systems towards high‐calorie foods

Abstract

Nutritional state (e.g. fasted vs. fed) and different food stimuli (e.g. high-calorie vs. low-calorie, or appetizing vs. bland foods) are both recognized to change activity in brain reward systems. Using functional magnetic resonance imaging, we have studied the interaction between nutritional state and different food stimuli on brain food reward systems. We examined how blood oxygen level-dependent activity within a priori regions of interest varied while viewing pictures of high-calorie and low-calorie foods. Pictures of non-food household objects were included as control stimuli. During scanning, subjects rated the appeal of each picture. Twenty non-obese healthy adults [body mass index 22.1 +/- 0.5 kg/m(2) (mean +/- SEM), age range 19-35 years, 10 male] were scanned on two separate mornings between 11:00 and 12:00 h, once after eating a filling breakfast ('fed': 1.6 +/- 0.1 h since breakfast), and once after an overnight fast but skipping breakfast ('fasted': 15.9 +/- 0.3 h since supper) in a randomized cross-over design. Fasting selectively increased activation to pictures of high-calorie over low-calorie foods in the ventral striatum, amygdala, anterior insula, and medial and lateral orbitofrontal cortex (OFC). Furthermore, fasting enhanced the subjective appeal of high-calorie more than low-calorie foods, and the change in appeal bias towards high-calorie foods was positively correlated with medial and lateral OFC activation. These results demonstrate an interaction between homeostatic and hedonic aspects of feeding behaviour, with fasting biasing brain reward systems towards high-calorie foods.

Imaging methodologies and applications for nutrition research: what can functional MRI offer?

“…In addition, manipulating food motivation by varying energy content of food images is associated with f MRI activation in hypothalamus, ventral stratium, cerebellum and frontal middle gyrus to high-energy food images compared with low-energy images (66,(69)(70)(71) .…”

Brain Activation by Visual Food-Related Stimuli and Correlations with Metabolic and Hormonal Parameters: A fMRI Study

“…The sample size was only moderate, although sample sizes of 12-15 are customary in fMRI studies. Lately it has been shown to be of importance to categorize the visual food stimuli in low versus high calorie stimuli as this could influence the results especially during the fasting state [47]. Also, recently published data have implicated adiponectin in regulating food intake and energy expenditure [48,49].…”

Potential benefits of satiety to the consumer: scientific considerations

“…Acute food deprivation increases the reinforcing value of food (127,128) , the subjective appeal of high-energy density foods and the activation of brain reward systems in response to pictures of these (43) . Sustained, hypoenergetic diets generally produce increased reports of hunger (94,110,114,129,130) and changes in hunger in response to dieting can predict successful/unsuccessful weight maintenance (131) .…”

“…Pleasant feelings, or at least satisfaction or good mood, perhaps induced by pleasant memories of the meal (see below), may follow for 1 h or more after such a meal, provided that over-satiation has been avoided. In referring to satisfaction, pleasure and enjoyment, we are acknowledging that eating food is, normally, fundamentally rewarding to the brain (43) . It is recognised that there is an ongoing debate as to whether purely hedonic sensory pleasure ('liking') can be meaningfully separated from expressions of reward-based motivation ('wanting') (44 -46) .…”