Environmental, Behavioural and Social Factors
Environmental
Many lifestyle changes have occurred over the last 20 years and this has been paralleled by the rise in obesity. This has been attributed to a decline in levels of activity as well as a difference in diet, which is more important than the actual amount of food eaten.
Reduction in activity levels is considered to be the most important factor in the rapid rise in obesity levels. With reduced physical activity there is a rise in sedentary behaviour. For example, there is a reduction in school pupils participating in school sport and in pupils walking to school but a larger number watching TV and playing computer games.
The National Audit Office in the report “Tackling Obesity” (February, 2001) cites the following factors contributing to a reduction in the amount of physical activity undertaken:
- More cars owned and greater use of cars – Effect: Decrease in walking or cycling.
- 50 years ago there was much greater physical activity involved in daily living (the equivalent of “running a marathon every week”) - Effect: Less manual effort expended with the rise in use of modern domestic appliances and labour- saving devices such as washing machines, tumble- dryers, vacuum cleaners, dishwashers, and microwaves. In the workplace, the use of computers (and robots in some factories) and the rise in the number of sedentary jobs leading to the reduction in physical labour.
- The reduction in walking as a mode of transport for example, the “school run”. This is partly due to fears for personal safety and with certain ethnic groups this fear may be intensified. This can also be tied in with the increase in crime in urban areas preventing vulnerable members of society (such as the elderly and women) from venturing outdoors - Effect: Reduction in walking out of doors.
- In public places, the increased use of lifts, escalators and automatically opening/ closing doors - Effect: Discouraging physical activity.
- Less sport in some schools (as above), the reduction in children playing out of doors (children “being sent out to play”) - Effect: Less physical activity, less walking and cycling.
- Change in recreational pastimes from physically active pursuits to sedentary pastimes such as computer games, the internet and TV viewing - Effect: Reduction in physical activities in leisure time.
- Fear of racial harassment and cultural beliefs which may affect the level of exercise taken by some black and ethnic groups - Effect: Reduction in exercise levels taken by some members of society.
- In addition to reduced activity, which is a feature of modern life, there are other important factors predisposing to obesity:
Behavioural
Eating high fat, energy-dense foods and drinks:
- Fat provides 9 calories/ gram when metabolised
- Alcohol provides 7 calories per gram
- Carbohydrate provides 4 calories/ gram
- Protein provides 4 calories/ gram
The advertising and marketing of high-density processed and convenience foods with high sugar, salt and fat content has led to a much greater consumption of these foods and a decrease in consumption of milk, fruit, vegetables and unprocessed foods. Not only are high-fat foods not so satisfying (hence more are eaten), but also they have more than twice as many calories per gram as carbohydrates and proteins.
Nowadays, energy intake is significantly increased (though more food per se may not necessarily be eaten), with the consumption of sugary and high fat foods and drinks, especially in the form of snacking.
Cooking methods such as steaming (a method which enables micronutrients and substances such as potassium to be retained), are often no longer used. Processed and ready meals often contain much higher levels of sodium than usual. This may have effects which are not fully understood.
Eating habits are more disorganised with less formalised mealtimes and less recognition of the amount of food eaten.
Two other important factors are the consumption of alcohol, which provides considerable energy (7 calories per gram) and encourages appetite; and weight gain associated with the cessation of smoking, which can be as much as 2.8 kg in males and 3.8 kg in females.
However the health benefits derived from giving up smoking 20 cigarettes a day are still greater, unless the weight gain reaches or exceeds 11 kilograms.
Social
There is a marked social class difference in levels of obesity, with a strong prevalence of obesity in classes 4 and 5 as opposed to social class 1. This link is stronger in women, for reasons not fully understood. In 2001, 30% of women in routine occupations were classified as obese compared with 16% in higher managerial and professional occupations. (Social trends 34: Health Survey for England). The mechanisms are probably related to established habits of poor diet and exercise.
Factors, which are considered important, are maternal obesity and poor diet in pregnancy, lack of breastfeeding, poor weaning and topping up feeds to match with “bottle fed” percentile charts.
Amended April 2008
