1 Physical activity and dieting
There is a clear relationship between regular participation in physical activity and healthy measures of body composition and body fat. However, the number of people participating in adequate levels of physical activity remains relatively low. For example, in England just 60% of adults participate in the recommended 150 minutes of moderate physical activity each week (Sport England, 2016a) and only around 40% of men and 30% of women participate in sport, at moderate intensity, for at least 30 minutes on one or more days a week (Sport England, 2016b).
According to Weinberg and Gould (2015) the main reasons given by adults for not participating in physical activity are lack of time, lack of motivation, lack of energy and health-related issues. If we can overcome these barriers, participation in physical activity can provide several key benefits for our health (see Figure 2), such as maintaining a healthy weight and reducing the risk of diseases such as Type II Diabetes (Department of Health, 2011).
Physical activity influences appetite and leads to improved overall fitness levels. In turn, higher fitness levels mean you gain advantages that benefit your weight control, due to the increased use of body fat as an energy source and the preservation of lean muscle mass. One of the major physiological advantages of exercise is that levels of fat in the blood are reduced. In the first activity, you will examine the influence of exercise on weight control compared with dieting.
Activity 1 Physical activity and weight control
In this reading activity, you will learn about the influence of exercise on weight control compared with dieting.
Read from ‘Activity and weight control’ up to, but not including, ‘Exercise and appetite’ on pages 320–322 from Chapter 13 of the book Fitness and Health by Sharkey and Gaskill (2013).
As you read, answer the following questions:
- What is the key message about the effectiveness of diet and exercise for weight control?
- What are the exercise recommendations for effective weight control?
- Why might exercise be more effective for weight control than dieting alone?
- The key message conveyed by the authors is that, for weight control, neither exercise nor diet alone result in the same level of long-term success as exercise combined with diet.
- The energy used during activity is related to several factors, including the duration and intensity of exercise. For effective weight control, Sharkey and Gaskill (2013) recommend moderate rather than high intensity exercise because more calories are used before exhaustion is reached. Others suggest that the total energy expenditure (duration and intensity) is most important. Sharkey and Gaskill (2013) also emphasise that greater fitness allows more activity and therefore more effective weight control; hence exercise frequency may be more important than intensity.
- Sharkey and Gaskill (2013) conclude that exercise and dieting combined is more effective than dieting alone. They refer to several studies which show that physical activity should be a key component of successful weight control programmes. This is because restricting calorie intake alone, by dieting, leads to a loss of lean tissue (muscle mass) and body water in addition to fat. They emphasise that when the body loses lean tissue it becomes less able to burn calories due to the decreased metabolic rate, and so when energy intake increases again, fat is regained more easily than prior to the calorie-restricted diet. Weight loss with exercise allows the decline in body fat levels without the accompanying loss of lean tissue. Indeed, exercise will increase lean tissue and thus increase basal metabolic rate (BMR). There is also the effect of excess post-exercise oxygen consumption (EPOC), where calorie expenditure remains high for a short while after the period of exercise (the recovery period).
Having examined the importance of physical activity for weight control you will now look at the link between physical activity and appetite.