Qn. “Does age have an effect on one’s appetite? I have noted that my five-year-old niece has developed a huge appetite for food yet her 60-year-old dad has to constantly be pushed to eat well.”
Anybody who has teenagers at home will tell you that they eat a great deal and seem to eat all the time. So, the answer to your question is a most definite yes. One’s age is to a very large extent a determinant of how much one eats.
That said, a number of preliminary points need to be made. The first and perhaps most obvious is the fact that for most people, a balance between the amount of food eaten and the amount of energy expended by the body is often in equilibrium.
Put another way, one maintains a steady weight for as long as one eats the amount of food that is equivalent to the energy that he or she expends. If one eats more than one burns then one puts on weight.
In children, and more so in the rapidly growing adolescent, the challenge is two-fold and hence the need for much food.
On the one hand, the act of growing requires much energy because so many complex changes are taking place in the body during this time.
In addition, and again as parents of teenagers will confirm, the children grow bigger by the day (it seems) and require new shoes, trousers and skirts almost every term! In addition to the energy required to make growth take place, the teenager is putting on weight and must, therefore, eat more than his/her parents who are not growing!
Many teenagers are also very active and need much energy to run around.
For the elderly at the other extreme, their energy needs are very little since even their movements are much reduced and, therefore, burn much less energy. As one grows older, they need to eat less and less because they burn fewer calories as they spend much time watching the sunset.
Two things come to mind with this point now made.
The first is a matter that former US President Barack Obama recently raised in South Africa. At Nelson Mandela’s birthday celebration he stated categorically that he is surprised at how much money he has. He also said he knows that many of those present (mostly Africans) had more money than he has, and by extension more than they will ever need to enjoy a lifestyle that could be considered opulent. That view resonates well with your question in that one of the most rapidly growing epidemics in Africa is obesity among the middle-class children and adults.
It is an epidemic that is well mirrored by the primitive accumulation of money in Africa, sometimes through corrupt means. Such people are said to be “eating” public money and hence their obesity. So, and this was Obama’s real question, “How much money is enough?” by extension, how much food is enough? In a sense, and in partial answer to your question, enough food depends on your energy needs as you grow. Whereas a teenager requires much food to grow, his less active grandmother will grow fat and die of diabetes if she eats as much as the teenager.
The second matter that your question brings to the table is that of the biology of food intake, obesity and healthy eating habits.
There are, (not surprisingly) two conditions in this discussion. The first and less common in Africa is anorexia nervosa — a major crisis in the Western world. The second is obesity in both children and adults, which has been blamed on the twin problem of eating too much junk and not doing enough physical activity. There are programmes in both the UK and parts of America that are designed to ensure that all children have a minimum number of hours of physical activity every day at school.
There are, however, some people for whom genes seem to play a big role in weight gain. For such people, the struggle to lose weight becomes almost too hard and is not affected by anything we have suggested so far. For such people, it seems that certain hormones that tell the stomach it is full of food do not seem to work well. In the circumstances, the person eats huge amounts of food before one becomes aware of a full stomach.
Medical intervention by way of various surgical means can be lifesaving as it could prevent diabetes, hypertension and some joint problems. Some depressed people eat too much.
As you can see, how much one eats is determined by many factors, including age.