Causes of Obesity

Obesity results when there is an imbalance between energy intake and energy expenditure. In other words, you consume more calories than you expend in your daily activities. Weight gained during certain critical periods of your life more commonly lead to an increased number (as opposed to increased size) of fat cells and make obesity more difficult to treat. These time periods are :

• Between 12 and 18 months of age.
• Between 12 and 16 years of age.
• Adulthood when a person gains in excess of 60% of their ideal body weight.
• Pregnancy.

During these periods, an excessive amount of weight gain causes an increased number of fat cells. Once a fat cell is formed, you generally cannot get rid of it. However, recent studies imply that use of certain medications can destroy fat cells and that a decrease in the number of fat cells can occur if you maintain a lower body weight for a prolonged period of time.

What causes one person to gain weight while another person maintains their weight ? There are differences in people, and several factors that contribute to these differences have been identified :

Age

As a general rule, as you grow older, your metabolic rate slows down and you do not require as many calories to maintain your weight. People frequently state that they eat the same and do the same activities as they did when they were 20 years old, but at 40, are gaining weight. This will happen. Metabolism slows down with advancing age.

Gender

Gender is also an important factor. Males have a higher resting metabolic rate than females, so males require more calories to maintain their body weight. This higher resting metabolic rate is primarily due to the increased lean body mass (mainly muscle tissue) males have compared to women. Additionally, when women enter menopause, their metabolic rates decrease significantly. That is part of the reason why many women start gaining weight after menopause.

Activity level

Active individuals require more calories than less active ones. Physical activity tends to diminish appetite in obese individuals while increasing the body's ability to preferentially metabolize fat as an energy source. It is believed that much of the increase in obesity in the last 25 years has resulted from the decreased level of physical activity in everyday life (such as emailing coworkers instead of walking over to their desks.

The above information thankfully comes from the weight.com at the following link.