Obesity, overeating and hormones

What is obesity?

Obesity is a condition in which a person has Body Mass Index > 30. BMI is calculated as weight (in Kg) divided by height square (in meter). There are differences in categorizing overweight, whereas in Asia, BMI > 25 is already categorized as overweight, while in US and Europe, the value is BMI > 30. But all agreed that obese is BMI > 35. However, after BMI > 20, risk of having degenerative diseases is said to be increased arithmetically. Cardiovascular disease (CVD) and Type 2 diabetes are among the top problems for obese people. In a simple word, obese is a mother of all diseases.

Primary cause of obesity: overeating

Overeating is predominantly accepted as source of obesity. In a simpler way, obesity can occur while a person having more energy intake than he needs to. The surplus of energy, primarily from food we eat, is stored beneath our skin as lipid.

Obesity and gene

The theory of genetic factor in obesity is developed owing to the finding of leptin and other dopaminergic hormones that regulate energy intake and their relationships with neuro-signaling. Genetically leptin-impaired person would be more likely to have obesity. However, a link between obesity and genes (Ob, FTO, MC4, NPC1, MAF, and PTER) is yet to be understood.

Feeling hungry and full: is it all about leptin?

Leptin, a 16 kda protein secreted by adipocyte (fat cells) to blood stream, is a hormone that regulates energy intake and body weight. If leptin level increased, a sense of fullness is triggered. However, memory of feeling full can be altered, resulting leptin-resistance. In simple words, the same amount of food that triggers fullness in the past is not enough to produce the same effect now. Leptin-resistance would increase food intake as the person requires more to feed their satiety of food. Leptin-resistance people are subjected to abnormality of chromosome-7.
An article in Nature stated that leptin may be responsible for, but it is not the sole player in gaining weight. Ghrelin (apetite hormone) and to a lesser extent insulin (blood-glucose hormone) share responsibility for obesity.

Other hormones that may related to obesity are serotonin, norepinephrine and dopamine. Serotonin has also been understood to have an inhibitory effect on eating behavior, despite its main role in depression. Abnormality in norepinephrine capacity may alter eating behavior. Dopamine, a precursor of epinephrine and norepinephrine, is a neurotransmitter that regulates feeling of fullness as food consumed.

Two ways of altered food indulgent
Dopaminergic activity as a result of leptin level in blood stream is captured in hypothalamus and amigdala, which then trigger sense of hungry and full. This level is said to be affected by memory (dopamine-related neuron) caused food addiction in a way similar to drug addiction.
Palatability is highly affected by appetite arousal substances in food namely fats, sugars and minerals/salt. In the end, those would increase food intake.

Tricks to avoid overeating and obesity

There is so much information on how people can control their weights. For example, having a balanced diet and excercise is by far the most popular solution. Caloric restriction or simply fasting, recently, emerges as an alternative to diet method despite having a lap band surgery.
Reducing weight and maintaining shape are not easy tasks, a report suggest only 1o% can overcome weight rebound after several years of successful diet. Long, long time ago, a wise person said: stop eating before feeling full and doing fasting regularly. Those two suggestions are most effective way that incorporate our spiritual, mental, and physical vigilance to stay in shape.


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