There's a big difference between foods that contain compounds that can physically affect your brain chemistry and foods that just make us feel good. Foods in the latter group are called comfort foods. While foods that produce physical happiness affect our physiology, comfort foods provide happiness on a psychological level. When you're down in the dumps, however, you probably won't care about the distinction, as long as you feel better.
Psychological studies have turned up evidence that the comfort foods we crave are actually artifacts from our pasts [source: Galisson]. We all have memories of happier times, and by eating foods that remind us of those times, we symbolically consume that past happiness. Comfort foods can also be linked to specific people in our lives: Eating a specific food that a loved one favored can produce happy thoughts by triggering fond memories or associations of that person [source: Wansink]. This makes comfort foods fairly unique to each individual. If your childhood birthday parties represented the pinnacle of happiness for you, you'd likely crave birthday cake or some variation of the dessert when you're blue.
Although comfort foods (or the events attached to them) vary from person to person, the foods we associate with comforting or happy emotions vary by gender. A 2005 Cornell University survey of 277 men and women found that females tend to seek comfort in sweet and sugary foods like ice cream, while males prefer savory comfort foods like steak and soup [source: Smith]. The study also found that men tend to use comfort foods as a reward, while women often feel guilty after indulging.
Interestingly enough, the females' guilt may signal an evolutionary leg up over males. Regular comfort eating as a response to stress -- especially chronic stress -- is considered an unhealthy behavior akin to smoking cigarettes. Why? Because comfort foods are often low on nutrition. One 2007 study found that when given both grapes and hot buttered, salty popcorn to eat while watching a sad movie, the participants ate far more popcorn [source: Lang].
Read the next page to learn about how some foods may help you fight against depression, and how eating less can also make you happy.