The drive to eat is primal, but it lessens
with age. A recent review has examined the change in appetite as we get older,
and the possible bad effects that may result.
Both men and women experience an increase in body
mass and body fat from the 40s onwards – we call it “middle age
spread”.
This happens at a
time when many studies have shown that food intake is decreasing. The
“spread” must be due, therefore, to a decrease in physical activity,
an alteration in the rate we burn food (metabolic rate), or a change in the way
fat is stored. Keeping active is the best way to combat this problem.
After fasting
overnight, older people are less hungry than younger people, and feel full
with less food. This is probably due to delayed emptying of the stomach. The
decrease in food intake with age is mainly due to lessened fat intake; whatever
drives appetite reduces interest in fatty foods while maintaining interest in
other foods.
Appreciation of the
pleasurable qualities of food (e.g. taste, aroma, texture, temperature)
declines with age. This causes elderly people to select more variable diets, in
order to compensate for lessening powers of taste and smell. In particular,
older persons require more salt and bitter tastes to satisfy them, while taste
for sweets are less affected.
Decrease of appetite with age can have serious consequences. A condition
known as protein-energy malnutrition has been reported to occur in up to 15% of
community-dwelling older persons, 65% of hospitalized older patients, and 85%
of the institutionalized elderly. Unfortunately, this condition is rarely
recognized and is often not treated.
Protein-energy malnutrition is associated
with prolonged hospitalization and even mortality. Associated conditions
include immune deficiency, pressure ulcers, anemia, falls, cognitive deficits
and delirium.
Apart from
age-related loss of appetite, there are many other causes of weight loss in the
elderly which may lead to malnutrition: social (poverty, functional impairment,
isolation, abuse etc), psychologic (dementia, depression, bereavement,
alcoholism) and numerous medical conditions, including medications. Many of
these can be addressed with subsequent improvement in the nutritional state,
but there remains the question of how to specifically treat malnutrition.
Energy supplements are
beneficial in undernourished elderly persons – they result in weight gain,
fewer falls, lessened complications after hip fractures, and decreased death
rates in hospital. It must be emphasized, however, that there is no evidence
that energy supplements help healthy elderly individuals, despite the claims of
manufacturers.
Commercial liquid
energy supplements, mixed with whole (4% fat) milk to reduce cost, can be taken
by mouth. Where necessary, intravenous feeding with energy supplements is used
to treat severe malnutrition.
Although several types of drugs have been tested for their ability to
improve appetite in the elderly, none has become firmly established, as the
side effects are too pronounced. The risk associated with the loss of appetite
in aging is that it may occur along with a social or medical condition,
resulting in protein-energy malnutrition.
Consequently people, as they get older,
should be in the regular care of a physician who is alert to the possibility of
conditions which may combine with the normal reduction in appetite to
precipitate malnutrition, and who will take the necessary actions to prevent
this.
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