-How much we eat and its nutritional value is one factor potentially affecting human longevity.
Other factors include how much exercise we take, our genes, whether we smoke or drink a lot of alcohol, our occupation and interests, our personality and our social life.
However, eating too much or too little is bad for our health. It could make us more susceptible to chronic illness - and may even knock years off our lives.
If we are aiming to eat less we need to ensure we eat a healthy diet, to get enough vitamins, minerals and nutrients.