FAT LOSS: FIXED FACTORS

Age. Age differences are most obvious at four different stages—childhood, adolescence, middle age and elderly—but age also interacts with gender and other variables in influencing the effects of exercise for fat loss. There are big differences between childhood and early adolescence and early and late adulthood in a range of factors which have relevance for fat loss. Metabolic rate, for example, is much higher in childhood and is known to decrease at the rate of around 2 per cent per decade after age 20. This means that by age 70, the body is burning about 10 per cent less energy at rest than it was at age 20, largely due to changes in the fatilean mass ratio. When this is coupled with a decrease in ‘spontaneous physical activity’ (SPA), a decrease in the sensitivity of ? receptors on the fat cell surface modifying substrate utilisation, changes in body fat distribution and muscle content, and changes in thermogenesis, all favouring a higher fat metabolism in the young, the extra difficulty older people have in maintaining a low level of body fat is more understandable.

Decreases in aerobic capacity and muscle strength suggest that if fat losses are to be gained through physical activity in the older age groups, attention will need to be paid to the total amount of exercise (at a low-moderate intensity) and the level of incidental and spontaneous activity. Maintenance of muscle mass through resistance training may also be important in maintaining metabolic rate which is thought to be reduced due to the atrophy of type II muscle fibres with ageing.

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