WEIGHT LOSS: WHAT IS MORE IMPORTANT, NUTRITION OR ACTIVITY?
To produce a negative shift of the energy balance equation to promote weight loss either:
- less energy has to be consumed
- more energy has to be expended.
Evidence would suggest that the best approach is to combine the two. Those who are physically inactive and are unable to increase their activity levels significantly, perhaps because of physical disability, will struggle to effect long-term weight loss. However, those who merely become more active are usually disappointed by their slow rate of weight loss (perhaps as little as 0.5 kg per month). Increased physical activity promotes the retention of lean muscle mass, which, in itself, is beneficial but that might not lead to a very significant reduction in body fat mass.
An individual can only decrease his or her dietary intake by so much and a daily calorie deficit in excess of 500-600 calories might produce symptoms of nausea, headache and light-headedness. In addition, any decrease in calorific intake over and above this level could result in poorer overall levels of nutrition, with micronutrient loss leading to vitamin and mineral deficiency. It would therefore appear that, for the majority of overweight people, the most sensible approach towards weight loss and producing a negative shift in energy balance equation is to incorporate both decreased dietary intake and increased physical activity.