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The primary reason that people in our society are unhappy with their weight is due to appearence. Fortunatly, people also are aware of the health hazards that are related to obesity. An excess of body fat occurs when people intake more food energy than they spend on a consistant basis. Obesity itself has many interrelated causes.
Fat Cell Development:
Much of the excess energy that is consumed but not expended is stored in fat cells. Both the number and the size of the fat cells is what reflects the amount of fat on an individuals body. During growth, fat cells increase in number. When energy intake excedes expenditure, fat cells can also increase in size. These cells can also divide upon reaching their maximum size. So when an individual's fat cells increase in size and or number, obesity occurs. These same fat cells will shrink in size but not in number with weight loss. This is why a person who has lost weight can regain it rapidly.
Genetics:
An important component to determining a person's body weight and composition has to do with genetics. If both parents are obese, chances are greater that their children will also be obese. It is also genetics that may determine the tendency to gain more weight than others. The way energy is spent is also partly genetics. Similarities within families is much easier to compare than based on sex, age, and body composition alone.
Metabolism:
Enzyme lipoprotien lipase(LPL)is what promotes fat storage in both fat and muscle cells. People with high LPL activity store fat well therefore, obese people have high LPL activity. (New England Journal of Medicine 322 (1990):1053-1059) This also means that even a small energy intake will have a more profound impact on obese people rather than on lean people. Women produce abundant amounts of LPL in their breasts, hips and thighs, men produce LPl in the abdomen. This explaines why men readily gain and store obese fat in the middle, while women generally gain in the lower areas.
Overeating:
Although it is not necessarily accurate, the obvious explination for obesity is overeating of overweight people. Miscalculation and reporting often leads to eating more than the individual believes. This in turn also may include that the individual is not quite as active as they believe themselves to be either. Obese people who keep track of their food intake in attempts to lose wait but fail to do so often end up in "denial". Denial being that they begin to blame genetic and metobolic factors rather than recognizing and taking full responsibility for their behaviours.
Inactivity:
Some individuals may be obese not because they overeat but because they are inactive or spend too little energy. People must be physically active if they are to eat enough food to deliver all of the required nutrients without an unhealthy weight gain. Technology has prompted a decrease in the amount of physical activity today. Underactivity is probably one of the most important contributing factor in obesity.
Inactivity alone fails to explain away the causes of obesity. Fat cell development, genetics, metabolism and overating are important factors as well. Some causes are under people's control and some are out of control. After all, no two people are alike. A healthy lifestyle and awareness are the best things an individual can do in order to keep their own lives in control.
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