There are many factors affecting the food decisions we make. Some are more complex than others, and often it has less to do with conscious decision making on our part and more to do with the food environment in which we find ourselves.
The current food environment in most Western cultures is often described as ‘obesogenic’, meaning ‘obesity-promoting’. This refers to the constant availability and accessibility of very energy dense (lots of calories per gram of food), palatable and hedonically satisfying foods that are persistently marketed to us in such a way as to grab our attention and make us want to buy and eat them. Within this environment, studies have shown that the number of fast food restaurants in a neighbourhood is significantly associated with an individual’s risk of overweight, obesity and stroke – so simply living nearer more outlets means you are more likely to eat there (and suffer the health consequences).
"Within this environment, studies have shown that the number of fast food restaurants in a neighbourhood is significantly associated with an individual’s risk of overweight, obesity and stroke – so simply living nearer more outlets means you are more likely to eat there (and suffer the health consequences). "
Our age can also be a factor. Children are heavily targeted by fast food marketers, using children’s toys and promotional tie-ins with children’s films, as well as establishing play areas at restaurants also mean the number of fast food meals eaten by children has risen. Adolescents are often found to eat the most fast food, sometimes consuming over 60% of their average daily energy requirement in one sitting, an effect that has been seen to be particularly exaggerated in those with overweight.
In addition, as the prevalence of obesity has risen, so has the amount of food and drink consumed outside of the home (such as fast food).
Snack foods and fast food are typically hedonically highly gratifying, as they are energy dense, high in dietary fat and/or sugar and salt, and low in dietary fibre. If alcohol is added into the mix, then we eat more of these types of foods.
Alcohol not only stimulates appetite but also is a potent disinhibitor of many behaviours, including eating, so those who regularly consume alcohol may also find that they eat more fast food than those who drink less.
I don't believe that fast food IS so tasty! This question assumes that we are born with natural taste preferences and that fast food naturally fits these. I think that we learn our taste preferences through exposure to different foods (we like what we are familiar with), through watching others (we like what others eat) and through association (we like whichever foods we associate with nice things such as smiling parents, good times or feeling happy). To some, fast foods may be tasty because they have learned to like high salt, high fat or high sugar foods. But to others who have not learned this fast foods taste plastic, artificial, salty, oily, greasy or just plain 'grim'. So the question makes many assumptions that I just don't think are justified!