Weight loss should be gradual and crash diets should be avoided, writes Dr Giles Warrington
For many people, apart from wanting to improve general health and wellbeing, the primary goal of engaging in a programme of regular physical activity is to lose weight. As you become older there is a natural pattern towards increased weight and elevated body fat levels. Current data suggests that about half of the adult Irish population is overweight.
Any attempt to maintain a healthy weight is influenced by a number of complex interactions including socio-cultural, psychological, genetic and lifestyle factors making the determination of the primary causes of weight gain, overweight and obesity highly individual.
Despite this, there is little doubt that energy expenditure associated with regular physical activity has the potential to play an important role in energy balance and subsequent weight control. What is critical to long-term weight maintenance, following weight loss, is the ability of individuals to adopt habitual physical activity practices.
A number of important considerations need to be taken into account when designing and prescribing physical activity programmes for weight loss and subsequent weight maintenance. These are based around the FITT principles:
F - frequency - how often?
I - intensity of exercise - how hard?
T - time or duration of the activity - how long?
T - type - the type or mode of training (eg endurance, strength, etc)
Each of these elements may be varied independently leading to a different overall training outcome for each individual. The types of activity adopted can vary from everyday activities such as walking and gardening to specific exercise such as jogging, cycling or swimming.
More recently, the use of resistance training as a useful weapon in the weight control armoury has gained wide acceptance. It is thought that such training leads to increased muscle mass, resulting in elevated resting energy expenditure.
Additionally, the associated strength gains may mean that overweight individuals are more able to perform everyday living tasks and other types of physical activity leading to further energy expenditure.
Current public health guidelines for physical activity recommend that adults should engage in "moderate" aerobic (endurance) activity for a minimum of 30 minutes for five days weekly. This equates a minimum of 150 minutes per week of physical activity, over and above that expended during everyday living.
Alternatively, you can participate in "vigorous" intensity activity for a minimum of 20 minutes on three days each week. While these guidelines will enhance general health and well-being, evidence suggests that engaging in exercise greater than these minimum standards may be required for weight loss and prolonged weight management.
Therefore, to maintain weight and prevent unhealthy weight gain it may be necessary to engage in exercise which exceeds the current minimum recommended amounts to the point where individual energy balance is achieved.
To prevent unhealthy weight gain, physical activity levels should be extended to approximately 45 to 60 minutes of moderate to vigorous exercise on most days while sustaining body weight following a period of significant initial weight loss may require 60 to 90 minutes of daily activity.
To gradually progress an overweight and previously sedentary adult to 300 minutes of exercise each week (which equates to expending around 2,000 kcal) may provide a significant challenge and may require the adoption of a number of behavioural and motivational initiatives by public health strategists, health promotion specialists and trainers.
The good news is that optimum body weight does not need to be attained for health benefits to be gained as evidence suggests that even modest reductions in body weight in the region of 5-10 per cent can significantly improve health so long as the weight loss is maintained in the long-term.
Although exercise alone has been shown to have a positive effect on weight regulation, the current scientific evidence overwhelmingly suggests that the combination of dietary modification and exercise is the most effective method of weight loss.
It appears that those who combine physical activity with dietary control maintain weight loss more effectively.
While consideration should be given to energy intake and food choices as well as other factors which may affect body weight, adherence to physical activity regimes has been shown to be one of the key predictors of weight regulation in the long-term.
Critical to any sustainable weight control programme is the need for a long-term maintenance strategy, without which weight regain is the likely outcome. To achieve this goal weight loss should be gradual and crash diets avoided as with the latter body weight is invariably regained and increased over time.
Appropriate weight loss strategies would attain a negative energy balance of 500-1,000 kcal per day achieved through a combination of increased energy expenditure and reduction in calorie intake.
This would result in a weekly weight loss in the region of 0.5-1kg.
• Dr Giles Warrington is a sport and exercise physioloigst and lecturer in the School of Health and Human Performance at Dublin City University