LAST Friday's report ("Exercise or diet: Which will help you lose weight?") suggested that dieting plays a much larger role in weight loss than exercise and that the impact of exercise on obesity is minimal.
London cardiologist Aseem Malhotra was also quoted claiming that "an obese person does not need to do one iota of exercise to lose weight". "He just needs to eat less."
These claims are inaccurate and can be misleading to the general public.
Body weight (fatness) is determined largely by the balance between energy expenditure, through physical activities and daily functions, and energy intake through eating, mainly in the forms of carbohydrate and fat.
We gain weight when energy expenditure is lesser than energy intake, and conversely, we lose weight when energy expenditure is higher than energy intake.
Therefore, weight loss can be achieved by increasing physical activity, decreasing food intake, or by a combination of both modalities.
This fundamental physiology of weight management recognises both dieting and exercise as effective modalities for weight loss, without favouring one over the other.
The American Heart Association and the American College of Sports Medicine recognise exercise as an effective modality for promoting metabolic health, including weight loss.
To achieve weight loss, these organisations recommend 60 to 90 minutes of moderate intensity physical activity on most days of the week to accumulate more than 300 minutes of exercise weekly.
The recommended duration can be accumulated with shorter bouts (more than 10 minutes) of activities over the day and the activities may include brisk walking, leisure cycling and sports, group exercise classes, and manual household or occupational tasks that cause a moderate pant.
Dietary intake should also be moderated to complement the increase in activity level.
The degree of weight loss achieved with dieting and/or exercising is likely to vary among individuals because of differences in other factors regulating fat storage in the body, for example, genetic predisposition, hormonal balance, and micro-organisms in the intestines.
That, however, should not trivialise the importance of regular exercise or good dietary habits because they also lead to other health benefits besides weight loss, such as higher cardio-respiratory fitness, lower risk of metabolic disease and preservation of bone density and muscle mass with age.
Current scientific evidence promotes both exercise and good dietary habits as important modalities for promoting cardio-metabolic health and weight management.
Fabian Lim Chin Leong (Associate Professor)
