Hormone controls cravings for food

 

Cambridge scientists have observed that the hormone leptin is responsible for reducing hunger, increasing feeling of fullness and controlling our fondness for food.

Scrabble Word Finder

Scrabble Cheat

Led by Dr Sadaf Farooqi and Dr Paul Fletcher, the University of Cambridge team have discovered that the appetising properties of food have a strong effect on the same brain regions that are 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 factor behind our eating behaviour.

The rewarding or appetising properties of food play a major role the pleasantness of eating and can lead to overeating when they over-ride the biological cues that govern hunger and fullness.

According to the researchers, 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 to the Cambridge team, was 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.

Leptin and food desire

They suggested that leptin, one of the major hormones controlling weight, might be the key.

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 hunger was reduced and they became more choosey about food and they lost weight.

In this study, funded by the MRC and the Wellcome Trust, the patients were asked to look at a series of pictures while brain activity was recorded using Functional Magnetic Resonance Imaging (fMRI for short)).

The fMRI scanner showed the parts of the brain were activated or ‘lit up’ in reaction to different pictures.

The pattern of brain activation in response to pictures of food was compared to that seen with pictures of non-food items such as trees, cars, and boats.

Some of the foods were really appetising (chocolate cake, strawberries, pizza) while others were rather bland (cauliflower, broccoli).

Dr Farooqi, University Department of Clinical Biochemistry, said: “More studies are needed to find out how these brain responses vary in people with weight problems in general. Research is needed to find out how leptin triggers other chemicals in the brain and how alteration of these pathways contributes to overeating and obesity.

“Such understanding will be a key step in the prevention and treatment of obesity. Importantly, the finding that the liking of food is biologically driven should encourage a more sympathetic attitude to people with weight problems.”

You’ve read it. Now review it.

Back to top

Back to top