BIOLOGY Volume 1 - A Guide to General Biology - 2004

8. HETEROTROPHIC NUTRITION

8.9. Malnutrition

8.9.2. Obesity

Today, obesity is the most common nutritional disorder in Britain, many European countries, and North America. Surveys of the adult population in Britain conducted in 1991 showed that 13% of men and 15% of women were overweight. Individuals are classified as obese if their body weight exceeds the average for their height and build by more than 20% (Fig. 8.28). A more accurate assessment is made by measuring The ratio of body fat to total body mass. In young men, fat accounts for about 12% of their normal body weight, whereas in young women it is about 26%. If this figure exceeds 20% for men and 30% for women, the individual is considered obese.

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Fig. 8.28. Patient with obesity.

Obesity develops when energy intake (from food) exceeds Energy Expenditure. Excess dietary fat, CARBOHYDRATES, protein, or alcohol are converted by the body into fat reserves. This does not necessarily mean that an obese person eats a lot. Studies have shown that many overweight individuals eat no more than lean people. Other factors can play a significant role, notably insufficient physical activity. There are, of course, exceptions; one individual weighing 365 kg was known to consume 15 chickens in a single sitting. However, the excess food intake leading to obesity can be relatively small. Nevertheless, small, regular surpluses accumulate over time and result in obesity. Beyond sheer quantity, the quality of food can also have a distinct effect. High-energy foods rich in carbohydrates and fats are much more likely to promote obesity.

Obesity tends to run in families, suggesting that there may be a genetic predisposition to the condition. In some cases, obesity is caused by physiological disorders resulting from abnormal hypothalamic function or underactivity of The Thyroid Gland.

Obese individuals are at a higher risk of developing cardiovascular diseases, as they typically have elevated Blood Cholesterol levels and higher blood pressure. Consequently, such individuals are prone to coronary atherosclerosis, leading to frequent Heart attacks in middle age, as well as varicose Veins.

The additional strain on the Skeleton leads to various mechanical complications, including flat feet, osteoarthritis, and spinal disorders. Movement becomes restricted, difficult, often slow and clumsy, which in turn increases the risk of accidents. Obese people also suffer from a higher incidence of diabetes and certain types of Cancer (such as Liver cancer).

Obesity also creates emotional problems. Children may become targets of teasing and bullying, while adults often experience persistent distress when comparing themselves to the slender models constantly promoted in advertising.

Unsurprisingly, obesity reduces life expectancy. Insurance companies have calculated that being 10 kg overweight at the age of 45 reduces a man's life expectancy by 25%. This risk is somewhat lower in women.

To prevent or treat obesity, it is necessary to reduce dietary energy intake so that energy expenditure exceeds intake. These Dietary Guidelines must be maintained even after normal body weight is restored. Additionally, patients require counseling to help them understand The Nature of the problem and commit to a lower-calorie diet, along with recommendations for structured exercise programs.