Scientists have discovered that leptin, one of the key hormones responsible for reducing hunger and increasing the feeling of fullness, also controls our fondness for food.
A University of Cambridge team, headed by Dr Sadaf Farooqi and Dr Paul Fletcher, have discovered that the appetising properties of food have strong effects on the same key brain regions responsible for rewarding emotions and desires. Using brain imaging technology, they show that these areas of the brain light up when individuals deficient in leptin are shown images of food.
Hunger influences what and how much we eat, but is not the only determinant of our eating behaviour. Eating is a very pleasant experience and the rewarding or appetising properties of food play a major role and can lead to overeating when they over-ride the biological cues that govern hunger and fullness.
Understanding eating behaviour therefore means that we must take into account physiological and hormonal pathways and also the brain processes evoked by the sight, smell, taste, or even just the thought, of food. More challenging still is to develop an understanding of the ways in which these two sets of processes the physiological and the brain/neural interact to shape our patterns of eating.
The authors sought to find a connection between the pathways in the brain that know when you are hungry or full and the parts of the brain that are involved in how much you desire and enjoy food. They postulated that leptin, one of the major hormones controlling weight, might be the key.
The hormone leptin is made by fat cells and circulates in the bloodstream to reach the brain where it acts to reduce hunger and increase fullness. The authors studied patients with a rare genetic disorder resulting in a complete lack of leptin. These patients eat excessively, like all types of food (including really bland foods) and develop severe obesity. After treatment with leptin, their hunge
Contact: Genevieve Maul
University of Cambridge