WEIGHT REGULATION: WHAT CAUSES OBESITY?

At its simplest, obesity is caused by an excess of energy intake over energy expended.

Average daily energy requirements

The average adult male requires approximately 2500 kilocalories per day to maintain his body weight.

The average adult female requires approximately 2000 calories each day.

This simple 'energy balance equation' is inescapable and an understanding of it must form the basis of any approach to weight management. However, weight regulation appears to be much more complex than a simple problem of energy in versus energy out. Other, powerful, extraneous forces are at work and, to a great extent, an individual's future as a 'fat storer' might be predetermined by genetic inheritance. Some experts estimate that as much as 70% of a predisposition to obesity is genetic. However, those implicated genes might not necessarily convey an inevitability of future weight gain. Our genes are switched on or switched off by environmental influences. In addition to genetic and environmental influences there are neurological and physiological influences, biochemical factors and cultural and socioeconomic issues, all of which could have a bearing on an individual's predisposition and ultimate development of obesity.

Obesity has been recognized and written about for centuries and it is not obesity per se but the rapid escalation in prevalence over the past 30 years that is giving rise to growing concern about the health implications of obesity. To understand the best ways to reverse the trend towards obesity, we need to understand its causes.

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