Obesity is linked to heart disease, diabetes and cancer.
Obesity is linked to heart disease, diabetes and cancer
Obesity is fast becoming the one of the West's most serious health problems.
The number of people who are obese is rising rapidly throughout the world, making obesity one of the fastest developing public health problems. The World Health Organisation has described the problem of obesity as a "worldwide epidemic". It is estimated that around 250 million people worldwide are obese, about 7% of the adult population
Obesity develops gradually over a period of time as weight is gained. Weight gain occurs when the amount of energy (calories) consumed as food and drink exceeds the energy which is used for exercise and other metabolic processes of the body. This is known as positive energy balance. The excess energy is stored principally as fat. Each kilogram of fat stores approximately 9000kcal. This fat can only be lost when the body requires more energy than is available from food and thus draws upon its energy stores. This is known as negative energy balance.
Energy balance is tightly regulated in most people and does not usually require conscious control. A change in life circumstances that alters either the diet (and thus energy intake) or activity (and thus energy expenditure) can lead to weight gain or loss. It is often difficult to identify these changes as only a small imbalance can lead gradually, but perceptibly, to changes in body weight and fatness
Factors which increase the likelihood of obesity
There are a number of factors which seem to predispose an individual to obesity. It is clear that obesity runs in families, is more common in some ethnic groups and is seen more frequently in developed countries where there is an inverse relationship between socioeconomic status and obesity. These observations provide some clues as to why some individuals become obese.
Genetics
Obesity tends to run in families. Children with two obese parents have about a 70% risk of becoming obese compared to less than 20% in children with two lean parents. This could be explained by environmental factors since families usually share the same diet, lifestyle and cultural influences. These habits tend to persist into later life. However, studies of adopted children have revealed weight patterns similar to those of their natural rather than their adopted parents and so obesity does have some genetic basis. However the degree to which obesity is genetically determined is still under discussion. Detailed studies of genetic transmission, including studies of mono- and dizygotic twins, have placed the influence of genetic factors from as low as 5% to more than 50%.
Over 50% of adults in the UK now weigh more than the medically recommended level.
The prevalence of obesity (severely overweight) has doubled in the past decade and now affects more than 15% of the adult population.
Obesity raises the risk of a whole range of physical diseases - including coronary heart disease, hypertension, diabetes, degenerative joint diseases, and some cancers.
A fat cell does not function alone, it requires help from a complex enzyme system. Enzymes facilitate the transport of fat in and out of the fat cell. The enzymes that help ...
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Over 50% of adults in the UK now weigh more than the medically recommended level.
The prevalence of obesity (severely overweight) has doubled in the past decade and now affects more than 15% of the adult population.
Obesity raises the risk of a whole range of physical diseases - including coronary heart disease, hypertension, diabetes, degenerative joint diseases, and some cancers.
A fat cell does not function alone, it requires help from a complex enzyme system. Enzymes facilitate the transport of fat in and out of the fat cell. The enzymes that help store fat are called the lipogenic enzymes, and the enzymes that help release fat are the lipolytic enzymes.
Men and women have roughly the same number of fat cells but the difference is the enzyme systems and the size of the fat cells. Women have more lipogenic enzymes for the storage of fat, and the more you can store, the bigger the fat cell. Men have more lipolytic enzymes for the release of fat, and therefore have smaller fat cells.
Why do people get fat?
The reasons for this are quite complex and it's not possible to give one definite answer. Some people, probably only about 5% of those who are obese (the technical term for people who are between 20 and 25% over their 'normal' body weight) have body imbalances, usually caused by damage to the hypothalamus, the part of the brain which controls hunger. In most people, however, it is due to them more food than they actually need. We all need to gain energy from the food that we eat for the activities we carry out. If we take in more energy than we expend over a long period of time, we will gain weight, as the excess energy is stored as fat. To lose weight involves taking in less energy than we expend: the best way to do this is to eat a healthy, balanced diet, and to take plenty of exercise.
It should come as no surprise that obesity is only really a problem in 'developed' countries where people have a high standard of living. In the USA, for example, between 50 and 70 million people are obese and about 65% of 50-60 year old women and 38-48 year old men are 10% heavier than they should be.
Fats keep the body warm.
They also protect organs like the liver and kidneys.
When we run marathons or take part in endurance events, our body uses fats as an emergency energy source once all our carbohydrates have been used up.
Fats are found in bacon, fatty meats like sausages, butter, margarine, cooking oil and salad cream, most cheeses, milk, nuts and sweets and chocolate.
There are two types of fat:
? Saturated fats: These are found in animal products such as meat, cheese, milk and cream.
The cholesterol in these fats can clog arteries and lead to high blood pressure and heart disease.
? Polyunsaturates are found in fish oils and products made from vegetable seeds such as sunflower and corn.
Keeping body fat under control can be very difficult for a lot of people, and fortunes are made devising new "diets" because more people are overweight in this country than ever before. There is also a fear of fat that is causing some people, women and girls especially, to stay dangerously underweight. The only way to stay an appropriate weight is to keep a balance between food intake and the calories we burn.
What two chemicals make up lipids and what happens if the lipids stored
Lipids are a large and varied group of organic compounds. Like carbohydrates, they contain carbon, hydrogen and oxygen, although the proportion of oxygen is much less in lipids. They are insoluble in water but dissolve readily in organic solvts such as acetone, alcohols and others.
Lipids are of two types; fats and oils. There is no basic difference between these two, fats are simply solid at room temperatures (10-20 degrees celsius) whereas oils are liquids. The chemistry of lipids is very varied but they are esters of fatty acids and an alcohol, of which glycerol is by far the most abundant. Glycerol has three hydroxy (-OH) groups and each may combine with a separate fatty acid, forming a triglyceride. This is a condensation reaction, and so hydrolysis of the triglyceride will again give glycerol and three fatty acids.
As most naturally occurring lipids contain the same alcohol, namely glycerol, it is the nature of the fatty acids which determines the characteristics of any paticular fat. All fatty acids contain a carboxyl group (-COOH). The remainder of the molecule is a hydrocarbon chain of varying length. This chain may possess one or more double bonds, in which case is it unstaurated, and if it has no double bonds then it is unsaturated.
Lipids have many functions: they are an energy source and can be broken down to yield double the energy of carbohydrates. For this reason they make excellent energy stores. They also act as insulators as they conduct heat very slowly and so can help retain body heat. Lipids also provide protection, as a packing material around delicate organs, and can function as a waterproof layer.
Centre for Health and Social Research (1999). Community Development Approaches in Primary Health Care - Options for Obesity Management. A report commissioned by HEBS/NBS/SCPGMDE, Edinburgh.
A study (1) of US adults from 1988 through 1991 found 33% to be obese (defined as more than 20% overweight), 25% higher than in the years 1976 through 1980.
Recent guidelines (2) recommend 30 minutes per day of moderate exercise on most or, preferably, all days. To lose weight, it's best to exercise 7 days a week if possible.
This, of course, may not be so easy. One big factor in exercising regularly is an accessible workout. Walking is not only accessible but one of the best activities for losing weight and gaining fitness. The ultimate goal is 60 minutes of walking or other comfortable exercise each day. But start with whatever you can comfortably achieve, even if it's only 1 minute. Begin at a leisurely pace.
Psychological effects. Brownell (9) has also speculated that the psychological impact of exercise is a key mechanism for weight control. Patients who exercise regularly are likely to be less depressed, have higher self-esteem, and have an improved body image (9). Regular exercise may also reduce stress and anxiety--elements that represent a high-risk situation for many dieters (17). An active lifestyle seems to be one of many factors that converge to help people manage their weight.
. Brownell KD: Exercise in the treatment of obesity, in Brownell KD, Fairburn CG (eds): Eating Disorders and Obesity: A Comprehensive Handbook. New York City, Guilford Press, 1995, pp 473-478
2. 17Kayman S, Bruvold W, Stern JS: Maintenance and relapse after weight loss in women: behavioral aspects. Am J Clin Nutr 1990;52(5):800-807
Exercise and Weight: Current Evidence
Simply having patients increase their level of exercise without restricting calorie intake is a relatively ineffective way to lose weight. When combined with a healthy diet, however, increased aerobic and strength exercise may result in optimal changes in body composition by contributing to a negative energy balance and preserving lean body mass.
Exercise, an Active Lifestyle, and Obesity Making the Exercise Prescription Work
Ross E. Andersen, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 10 - OCTOBER 1, 1999
Over the past decade, the prevalence of obesity has increased at an alarming rate in the United States and in other developed countries around the world. In fact, the World Health Organization has acknowledged that there is a "global epidemic of obesity."
What Can Physicians Do About Obesity?
Ross E. Andersen, PhD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 28 - NO. 10 - OCTOBER 2000
References
. Blackburn GL, Duyer J, Flanders WD, et al: Report of the American Institute of Nutrition (AIN) Steering Committee on Healthy Weight. J Nutr 1994;124(11): 2240-2243
2. Pate RR, Pratt M, Blair SN, et al: Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273(5):402-407
