OBESITY

typically low in the obese ● Effective in reducing mild clinical depression and anxiety which are common in obese people ● Improved self-esteem and general psychological well-being (6) ● Influences resting metabolic rate by preventing loss of muscle mass

Figure 2: Relationship of BMI to mortality and chronic lower back pain, than their non-obese counterparts.

Causes of obesity The overriding contributor to obesity is that energy (food) intake exceeds energy expenditure (influenced by physical activity and metabolic rate) over a prolonged period of time. Recent decades have seen a reduction in fat and total energy intake (3) but at the same time western lifestyle, influenced by increased motorised transport and labour saving devices, is encouraging us to be less active now than ever before. The sharp rise in the prevalence of obesity can be largely attributed to decreased physical activity levels rather than increased food consumption.

National surveys have consistently reported that 70% of men and 80% of women fall below their age appropriate activity levels (4). Similar studies have also provided strong evidence showing that obese indi- viduals participated in less physical activi- ty than their non-obese counterparts, fur- ther suggesting that inactivity is an impor- tant contributor to the development of obesity.

Research has shown that obese active peo- ple are at a much reduced overall risk for mortality and morbidity than those who are obese and inactive (5). Studies also demonstrate a dose response relationship where a reduction in risk of mortality and morbidity is associated with increasing activity levels.

Benefits of exercise In addition to influencing energy expendi- ture there are numerous other health bene- fits of physical activity for the overweight and obese individual (6): ● Favourably modifying blood lipids ● Reduction in blood pressure even in the absence of weight loss ● Effective management and prevention of NIDDM ● Improved functional capacity which is

14 SportEX

Physical activity and weight management A study reviewing the long-term effects of weight loss pro- grammes found that the average sustained weight loss was 4kg in four diet-only programmes, 4.9kg in five exercise-only pro- grammes and 7.2kg in three diet and exercise programmes (7). Exercise together with healthy eating is therefore critical to weight management in terms of both prevention and treatment as well as ongoing management. It should be noted however that exercise is likely to play a more critical role in weight loss for the overweight and mildly obese individuals than the severely obese as they may find difficulty in achieving sufficient levels of exer- cise to substantially influence energy expenditure.

Increases in lifestyle activity and reductions in sedentary pursuits also play a vital role in an overall weight management programme. All the evidence clearly demonstrates that long-term activity habits are associated with weight change patterns. Those who remain active and reduce their time spent in sedentary pursuits are most successful in maintaining a healthy weight throughout life.

The achievement of energy balance through energy expenditure is critical in obese people. In order to achieve this it is important to look at how activity fits into the individual’s daily lifestyle.

Figure 4 illustrates the contrasting patterns of energy expenditure between sedentary individuals, those who seek opportunity for exercise in their daily routine and those who typically perform a bout of vigorous exercise during their leisure time to make up for an otherwise sedentary routine. Even though activity of low intensity is slower in expending energy, it is likely to occur more often, resulting in greater total energy expenditure. Taken over weeks and months, this active lifestyle will make the largest contribution to energy balance. Therefore to maximise energy expenditure, the obese individual should increase incidental and routine daily movement.

Getting people active For weight loss to occur with obese people it is important to aim towards an addition- al 30 minutes of activity every day on top of their current daily routine. It should also be noted that for the very overweight per- son who achieves the recommended level of activity, an even greater total energy expenditure will be achieved due to the increased load involved in moving their