Grocery shopping on an empty stomach might not be the best idea when trying to lose weight. Food becomes more attractive when we’re hungry and we seem particularly susceptible to the luring properties of high-energy dense food like pizza or chocolate. Hunger and satiety are important in controlling daily food intake and securing adequate amounts of energy and nutrients. These physiological states influence food consumption and the food choices we make. In Nudge-it we explore the underlying brain mechanisms of hunger and satiety, their effect on our food choices and how this might help us stick to dietary goals.
Remarkably, body weight in most human adults is fairly constant despite day-to-day variations in food intake. This is achieved by an active process called energy homeostasis, which matches energy intake to energy expenditure over longer periods of time. This process is mediated by specialised physiological systems in the brain, in particular the hypothalamus. The hypothalamus senses internal energy-balance signals to regulate appetite and food intake. Such signals include circulating hormones that are generated in tissues like the pancreas, fat cells and intestines, but also nutrient-related signals like blood glucose. Furthermore, for actual food intake, integration of information from other so called higher brain systems like sensory, reward, and cognitive networks are required.
To ensure the motivation to seek food, a reward system evolved that reinforces useful stimuli and behaviors and makes the consumption of food and especially high fat, energy-dense food more likely.
Considering these extensive control mechanisms of food intake, the steadily increasing number of overweight and obese people in our modern society seems surprising. A major contributor to the obesity epidemic is seen in the abundance of highly palatable and energy dense food in modern Westernized societies. This food environment is in contrast to the food scarce environment in which the physiological control mechanisms that control our body weight developed and seems to overwhelm these.
The influence of physiological states like hunger and satiety on decisions about what to eat and how much to eat is undeniable. The importance for dietary choices and compliance to dietary goals, however, and the underlying brain mechanisms in humans are not well understood. In Nudge-it, we aim to improve the temporal and spatial description of the relevant brain circuits in humans for a better understanding of these processes. This will be achieved by the application of advanced imaging techniques including electroencephalography and magnetoencephalography for a detailed description of the interaction of the involved brain networks across time.
For the investigation of brain activity with high spatial resolution even in deeper brain structures like the hypothalamus, functional magnetic resonance imaging will be used. Furthermore, near red infrared spectroscopy will be evaluated in real world experimental settings. The overarching goal is to combine and improve the most advanced human brain imaging technologies to decipher the brain circuits involved in food choice in order to develop brain based intervention strategies for health improvements.