Time of day. Each of us gets into routines that psychologically "tell" our bodies we need food at the same time each day. "Part of the reason you're hungry at noon is because that's the time you've eaten for the last 100 days," said Randy Seeley, a professor of psychiatry at the University of Cincinnati.
Sight. MRI brain scans show that visual perception of food matters a great deal. The cerebral patterns of people who see photos of foods they like and foods they dislike are "very different," according to Seeley."The body anticipates when food is about to enter the system,"he said. The mouth waters at the prospect of something delicious.
Variety. It's no lie that "variety is the spice of life." We naturally like to have many different stimulations during the course of a meal, which is why many of us "make room" for dessert. However, even a little fruit in a salad can sometimes do the trick to head off a craving for sugar, according to Ann Gaba, a registered dietitian at New York Presbyterian Hospital.
Smell. Our sense of smell provokes the secretion of insulin, which arouses hunger. According to Sharron Dalton, a nutrition professor at New York University,"Smell and sight alone activate the appetite cascade."
Alcohol. Drinking seems to stimulate more eating, perhaps because it degrades one’s judgment, though this hasn't been proven by scientific studies. "Most people who are on a diet will say it's a lot harder to push themselves away from the table if they've been drinking," Seeley noted.
Temperature. As it gets colder, people eat more. Knowing this, restaurants keep their establishments cool. "Your metabolism drops when it’s time to eat, and eating warms you up," said David Ludwig, a professor of pediatrics at Harvard. "Heat is a satiety signal."
Refined carbohydrates. When we eat refined carbs, such as white bread, we get hungry again relatively quickly. This is because these foods drive down blood sugar, and when our blood sugar is crashing, we're going to be a lot more interested in food in general, Ludwig said.