There could be several factors which could be at play, when we try to determine as to why some people turn out to be heavier than others. Again the foot print of risks and potential of developing other medical complications is different for each patient of obesity. Science and technology are still to find that miracle cure that can quickly, permanently, and effectively rid obese patients of this disease in a healthy manner without any side effects. 

However, until such a wonder cure is found by the scientific, technical and medical community, it is up to the individual patient to resist to the temptations of excessive food and lethargy and to increase their metabolic rate to fight obesity, or else this disease can end up being a lifelong struggle for such patients.

Although there exist medical interventions that can get the patient rid of all the excess flab in a matter of a day through various kinds of weight-loss surgeries, it is still the health of the patient, their lifestyle and habits, that will eventually determine if the patient will survive such a surgery or will be able to maintain or improve upon the benefits extended by such a surgery. 

Therefore, the various medical interventions that exist at present are a mere temporary relief to the obese patient and not the final and permanent cure. Making the result last permanently is completely in the hands of the patient, and depends on the patient's own level of self-discipline and dedication. 

The temporary medical relief is a mere impetus to help the patient overcome the drastic physical, social, psychological, physiological and emotional side-effects of the disease. This way the patient is given the physical and psychological impetus to kick-start their process of recovery. Complete recovery however, is completely the patient's responsibility.

Gain in weight is the consequence of the body consuming more calories in the form of excessive food which does not get fully expended in carrying out the body's involuntary functions, represented by the metabolic rate, and in carrying out the normal physical level of activity of the person in concern. 

This in turn results in the excess and non-expended calories, getting converted and stored as layers of fat deposit for use during potential physical activity in the future. This is why exercising is important to burn these excess layers of fat deposits. This is also why maintaining a balanced diet is important to prevent the creation of fresh layers of fat deposits.

A person could turn obese owing to hereditary factors, hormonal imbalance, environmental factors, low metabolic rate, and addiction to eating, careless eating or emotional eating. Some people have a family history of having obese family members across the entire hierarchy of their family tree. Here genetic factors are responsible for obesity.

Some people may face hormonal imbalances, such as developing a thyroid problem, which results in obesity as a side effect. Some people's environmental factors such as their lifestyle, habits, sedentary way of living and outlook towards life, cause them to become obese inadvertently. Some people have or develop a low metabolic rate due to improper eating and sleeping habits.

And yet others may be simply addicted to food, or they may be careless about eating, such as eating in front of the television or computer, when you don't get to realize how much you have stuffed in already. Finally, some people may be emotional eaters. They may be eating for comfort or to alleviate depression temporarily by pleasuring their sense of taste etc.