Revealed - how the brain controls hunger

Although hunger is essential for survival, abnormal hunger can lead to obesity and eating disorders that are now reaching near-epidemic proportions around the world. The solution lies somewhere deep inside your brain. To unlock the mystery behind hunger pangs, researchers are creating a wiring diagram of the complex brain circuits that regulate the intense urge to munch in office or rush for refrigerator in night. 'Our goal is to understand how the brain controls hunger,' explained Bradford Lowell, an investigator with Massachusetts-based Beth Israel Deaconess Medical Center's (BIDMC) division of endocrinology, diabetes and metabolism.

Abnormal hunger can lead to obesity and eating disorders, but in order to understand what might be wrong - and how to treat it - you first need to know how it works, added Lowell, also professor of medicine at Harvard Medical School. The findings show that Agouti-peptide (AgRP) expressing neurons - a group of nerve cells in the brain's hypothalamus - are activated by caloric deficiency. When AgRP was either naturally or artificially stimulated in animal models, it caused mice to eat voraciously after conducting a relentless search for food. The hunger-inducing neurons that activate these AgRP neurons are located in the paraventricular nucleus - a brain region long thought to cause satiety, or feelings of fullness.

'This unexpected finding adds an important dimension to our understanding of what drives appetite,' said Lowell. To deal with this particularly complex brain region, the Lowell team is taking a step-by-step approach to find out how the messages indicating whether the body is in a state of feeding or fasting enter this system, said the study that appeared in the journal Nature. 'We are getting closer and closer to completing our wiring diagram. The nearer we come to understand how it all works, the better our chances of being able to treat obesity and eating disorders - the consequences of abnormal hunger,' explained Lowell.

With the rising rate of obesity the world over, we though it is time we tell you exactly what that excess bit of fat does to your body.

Causes your heart to malfunction

We all know that the heart is susceptible to blockages and arthrosclerosis. But do you know that fat has a huge role to play in the way your heart functions, the thickness of the muscles and its overall efficiency? When a person is obese, the fat present in the body, especially the fat around the belly, puts great pressure on the internal organs of a person. This fat pushes on the organs and pushes the diaphragm (a sheath that is present at the bottom on the lungs) upwards into the chest. This in turn puts pressure on the heart, literally pressing down on it.

Makes the muscles of your heart thicker and less efficient

Fat makes the heart work harder. It has to now pump blood through sclerotic arteries (accumulation of fat that makes the inside of blood vessels rough and pitted), a larger body and to failing organs that usually need more blood supply to function. All this extra work makes the muscles of the heart become thicker and tougher which can lead to severe complications like congestive heart failure, fatal heart attacks (due to arterial blocks), malfunctioning of one part of the heart muscle and perforations in the heart. (Read: Mega guide for losing weight the right way)

Crushes your lungs

If you are overweight you probably know what it means to be breathless while doing the most trivial of activities. What obesity does to your lungs is a phenomenal amount of damage. For one, the abdominal fat presses on the diaphragm, leaving lesser space for the lungs to expand. Literally crushing your lungs.

Makes your lungs overwork and can make you dizzy

The excess weight that the body has to carry makes your heart beat faster and your lungs overwork. With less space to expand it is no wonder that some obese people feel dizzy after working their body does not get enough oxygen.

Won't let you sleep

Another severe side-effect is obstructive sleep apnoea. This condition is brought about by the presence of excessive belly fat as well as the fat in and around the soft tissue of the neck. The fat in the belly presses down on the diaphragm, compressing the lungs and the fat around the neck presses down on the airway (windpipe) making it difficult to breath in a lying position. (Read: Sleep apnoea don't laugh away snoring problems)

Can make you dumber

We all value a sharp and smart person, but did you know that obesity can reduce your ability to think clearly and make good decisions? A study conducted by the Carnegie Mellon University, found that the brain of obese people works harder than people of a normal weight. It also found that the parts of the brain that were responsible for decision making and memory were hyperactive in obese people as compared to those of a person of normal weight. Moreover, because these people were more prone to inflammation and high blood pressure, it affects the communication system of the brain. This lack of communication is worse in areas that control impulsive behaviour. Read more

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