Title: Individual responses to weight reducing exercise programmes

 

Key words: obesity, weight reduction, compliance, inactivity, exercise, regimes, energy intake, energy output, weight loss, energy expenditure, appetite, satiety, hunger, anorexia, fitness, energy efficiency, low-intensity exercise, high-intensity exercise, fatty acid, mobilisation, energy-dense, refined, organic, endurance, lipid profile, complex carbohydrates, food intolerance, gut dysbiosis, genetic factors, psychological factors, introspection, depression, programmes, physical activity, physical fitness, quality of life

 

Date: Oct 2006

 

Category:

 

Nutrimed Module:

 

Type: Article

 

Author: Morgan, G

 

Individual responses to weight reducing exercise programmes

Obesity, which in the UK has doubled in the last 20 years (Garrow 2001), is now a major public health concern and is increasingly occupying the minds of dieticians, nutritionists, educationists and the medical profession. Weight reduction, a challenge for all concerned, is frequently bedevilled by patient compliance and an unpredictable response of the individual to the habitual combined treatment programme of diet and exercise. The variability of this response is considered in this review.

 

It is widely agreed that the increasing inactivity associated with the present day lifestyle is largely responsible for the present epidemic of obesity (Health Education Authority 1995). Diminishing energy intakes over the last 30 years have been more than met by declining energy output and a concomitant rise in obesity. For those engaging in exercise regimes, physiological and psychological factors come into play which determines the eventual response to the any weight reduction programme.

 

Exercise per se has a complex relationship with weight loss which is modulated through appetite, satiety and energy expenditure. Surprisingly, in the short-term there appears to be no close coupling between exercise and energy intake. In the immediate post-exercise period hunger is suppressed, leading to what has been called ‘exercise-induced anorexia’ (King NA 1994). The uncoupling of appetite and energy intake has been observed for periods of at least 3 days (King NA 1998), implying that over time exercise should lead to weight loss. Fitness gains and greater energy efficiency attest to the fact that a new equilibrium is established in the long-term and weight loss is able to be maintained (King AC 1991). The following points need to be made in order to explain the variable response often seen with such programmes:

 

1. The type of exercise programme.

Studies have shown that prolonged low-intensity exercise is more effective than shorter high-intensity exercise in promoting weight loss (Wareham 1998) and that such programmes only make a modest contribution to weight loss (Garrow and Summerbell 1995, National Institutes of Health 1998). Increased fatty acid mobilisation with endurance exercise is the likely mechanism (Sum 1994, Ballor 1994). 

 

2. Dietary changes associated with exercise.

Depending on the health consciousness of the subject, increased consumption of organic over high energy-dense refined foods promotes a more normal lipid profile and weight loss. These changes would be favoured by a switch to a diet rich in complex carbohydrates and low in fats, a diet more often adopted by those engaged in endurance type exercise. In addition fatty food taken after exercise counteracts the beneficial energy effects of exercise (Tremblay 1994), a relapse less likely to occur during the exercise-induced anorexia period of those engaged in this type of exercise. Restructuring of mealtimes around an exercise programme would in certain individuals be expected to likewise impact on appetite and energy consumption.

 

3. Food intolerances.

Food intolerances, which may be associated with gut dysbiosis, is relatively common in obesity and can lead to obesity which is refractory to all treatments unless identified (Anthony et al. 1997).

 

4. Genetic factors.

Population studies have shown that genetic influences contribute 24-70% towards obesity (National Institutes of Health 1998). There is obviously a close interaction with physical, environmental and psychological factors which, together, would have a determining effect on weight loss in the individual case.

 

5. Psychological factors.

A disciplined approach to both diet and exercise needs to be adopted if long-term results are to be achieved. Individuals vary in their ability to adhere to such programmes. Personality and psychological traits are the major factor in determining whether a weight reduction programme is successful or not. The above facts should be looked at in context. Increased physical fitness invariably leads to a sense of well being which increases the quality of life of the individual. Lessening of introspection and any associated depression may in themselves increase physical activity and lead to weight reduction. Such programmes are hard to maintain and even if unsuccessful in terms of weight loss such supplementary gains should nonetheless be valued in their own right.

 

References

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