Hereditary factors also play a part in a person's physical build. Obese parents are more likely to produce obese off-spring. It's also believed that obese people are more productive than others.

All of these other possible causes of obesity were highlighted in The International Journal of Obesity.

It would seem that more research needs to be undertaken before these additional factors can be proven to be major contributors towards obesity, but early indications lean towards this.

However in the absence of any conclusive proof, obesity sufferers should continue to regard a poor diet, and lack of exercise as being the two major causes of weight gain and obesity.

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When looking at the change in obesity levels in the US since 1970, then some of the increase in the proportion of adults classed as obese could be due to statistical changes over that period.

Middle aged European adults, all Afro-American adults, and all Hispanic adults have a markedly higher obesity level than young European adults. So when between 1970 and 2000 the proportion of Hispanic adults in the total US population increased from 5% to 13%, then statistically, the total proportion of obese adults increases.

And with the mean age of mothers at birth increasing since the 1960's, then it means that new born babies have a far greater chance of being obese than a person born 50 years ago.

This nexus between the age of a mother at birth, and the chance of the new born becoming obese is well known amongst sheep where the older a ewe is when it gives birth, the more likely is the lamb to have extra fat.

The decline in tobacco consumption over the last 30 years mirrors the increase in the number of over-weight and obese people during that time.

Another important factor that makes a contribution to overweight and obesity is the age of our mothers when we were born.

Studies have shown that the odds on a new born developing obesity later in life increases about 14% for every 5 years that the mother ages in child birth.

There are also medications on the market that have been shown to cause the retention of fluid, and hence increase BMI. A person taking a drug for the first time will experience a gain in weight, particularly if the drug is for diabetes, blood pressure, depression, an allergy, or contraception. One study of the effect of oral contraceptives on weight was estimated to show an average weight gain over a two year period of about 5kg (11.2 lbs)1

One of the most common and understood ways of gaining weight is to stop smoking. Nicotine is well known as a very strong and powerful appetite suppressant. So by ceasing to put the nicotine drug into a person's body, appetite becomes normal, the person feels hungrier, and therefore eats more.

It's been estimated that one in four men who have experienced weight gain in a recent 12 year period have done so because they gave up smoking. The comparable figure for women is about one in six.

The first suggested cause of obesity is lack of sleep. There is evidence in the western world that since the 1960s, the amount of sleep that the average adult gets has declined by about 90 minutes. The opinion is that bad sleeping habits have as much effect on a person's weight as does a poor choice of diet.

Another suggested cause is man-made poisons that have entered the human food chain. DDT, which is known to increase the fat tissue in mice, is also known to upset the human hormone system.

Natural hormonal change is known to increase puppy fat in children, and also is responsible for post-menopausal weight gain in women. Although the gain in weight from these factors may be relatively small, it can present difficulties for affected people wishing to reduce it.

Whilst the medical and nutritional professions regard overeating, together with a poor diet, and a lack of regular exercises as major causes of a weight gain problem and obesity, there are many minor factors that can be contributors.

The major causes and risks associated with excessive weight gain and obesity are....

The John Hopkins School of Health (US) recently completed a 3 year study into the health of Native Americans. The study found that there are many other factors besides diet and exercise that contribute towards the problem of a person gaining and retaining excessive weight.

Other Causes of Obesity