Do you eat to live or live to eat? We have a complicated relationship with food, influenced by cost, availability, even peer pressure.
But something we all share is appetite – our desire to eat. Increased appetite might have a physical or psychological dimension, but while hunger – our body's way of making us desire food when it needs feeding – is a part of appetite, it is not the only factor.
After all, we often eat when we're not hungry, or may skip a meal despite pangs of hunger, writes Professor Alex Johnstone, personal chair in nutrition at The Rowett Institute, Aberdeen University, in The Conversation.
Recent research has highlighted that the abundance of food cues – smells, sounds, advertising – in our environment is one of the main causes of over-consumption.
Our appetite is not fixed, it changes across our lifespan as we age. But as our choice of food will be an important factor to our health and well-being throughout our lives, it's important that we get into the right habits.
As Shakespeare might have put it, there are seven ages of appetite, and a better understanding of these phases would help us to develop new ways of tackling under-eating and over-consumption, and particularly the health effects such as obesity that follow.
There are growing calls for governments to protect young children from targeted junk food advertising, writes Professor Alex Johnstone of Aberdeen University
Watching television for three or more hours a day may increase a child's risk of developing type 2 diabetes, research suggested in July 2017.
Children who spend at least three hours in front of a screen are heavier and have greater insulin resistance, a study found. Both of these are risk factors for the condition.
Such youngsters also produce impaired amounts of the hormone leptin, the research adds. Leptin is involved in regulating appetite.
These results remained even after the study's participant's activity levels were taken into account, the study found.
Study author Dr Claire Nightingale from St George's, University of London, said: 'Our findings suggest that reducing screen time may be beneficial in reducing type 2 diabetes risk factors, in both boys and girls, from an early age.
'This is particularly relevant, given rising levels of type 2 diabetes, the early emergence of type 2 diabetes risk, and recent trends suggesting screen-related activities are increasing in childhood.'
The researchers analysed 4,495 children aged between nine and 10 years old.
The children were assessed for factors that influence their risk of developing diabetes.
Their body proportions, activity levels and the amount of time they spend in front of a screen - either watching television or using a computer - every day were also recorded.
First decade, 0-10
In early childhood, the body goes through rapid growth. Dietary behaviour built up in early life can extend to adulthood, leading a fat child to become a fat adult.
Fussiness or fear of food can contribute to meal time struggles for parents of young children, but a strategy of repeated tasting and learning in a positive environment can help children learn about unfamiliar but important foods, such as vegetables.
Children should experience some control, particularly in relation to portion size.
Being forced to 'clear the plate' by parents can lead youngsters to lose their ability to follow their own appetite and hunger cues, promoting overeating in later years.
There are growing calls for governments to protect young children from targeted junk food advertising – not just on television but in apps, social media and video blogs – since food advertising increases food consumption, contributing to becoming overweight.
Second decade, 10-20
In the teenage years, a growth in appetite and stature driven by hormones signals the arrival of puberty and the development from child into adult.
How a teenager approaches food during this critical period will shape their lifestyle choices in later years.
This means the dietary decisions adolescents make are intrinsically linked to the health of the future generations that they will be parents to.
Unfortunately, without guidance teenagers may adopt eating behaviours and food preferences associated with unhealthy consequences.
We need more studies to determine the most effective ways of tackling the rising burden of over and under-nutrition, particularly the link with poverty and social inequality.
Young women in general are more likely to suffer from nutritional deficiencies than young men because of their reproductive biology.
Teenage girls who become pregnant are also at greater risk since their body is supporting their own growth in competition with that of the growing foetus.
How a teenager approaches food during this critical period will shape their lifestyle choices in