A team of psychologists have determined that stress eating is more of a yo-yo than a simple pattern; they say stress eaters show a dynamic pattern of eating behavior that could have benefits in non-stressful situations. 

Not everyone eats more under stress. Many people instead eat less, so it is assumed that stress eaters have a bad habit that they need to regulate. To find out, the psychologist recruited volunteers to participate in a study on "first impressions." The participants interacted with an unfamiliar partner by video before meeting them in person. After making their own videos, the participants received one of three messages in return: Some heard that their partner had decided not to meet with them after seeing the video, while others heard that their partner liked them and looked forward to meeting them. A third control group was told that the experiment had to be canceled for other reasons.

Then the participants went on to participate in a supposedly unrelated study involving a taste test for three flavors of ice cream. They were allowed to eat as much ice cream as they wanted.

The results showed that, when faced with negative feedback, self-identified stress eaters ate more ice cream than participants in the control group, while self-identified stress starvers ate less. Munchers ate, on average, about 120 more calories' worth of ice cream than did the skippers.

But the stress eaters in the experiment ate less in response to a positive situation while skippers actually showed the reverse pattern, eating more after a positive experience. The skippers consumed, on average, 74 calories' worth more than the munchers. 

"These findings challenge the simplistic view that stress eaters need to regulate their eating behavior to prevent weight gain," says lead researcher Gudrun Sproesser of the University of Konstanz, in Germany. "Both skippers and munchers have their 'soft spot' for food, they just show different compensatory eating patterns in response to positive and negative situations.

"We predicted that munchers and skippers differ in food intake after experiencing a positive situation. However, we were rather surprised that the data showed an almost mirror image in ice cream consumption when compared to the data from the social exclusion condition."

What does it mean? It's just a data point but it says that the patterns of calorie consumption and behavior could significantly influence body weight over time. Stress is likely not a huge driver of eating more or less, the eating is just a learned response. Every 'chick flick' made in Hollywood has a scene where a group of women eat a carton of ice cream after some negative event, yet they all weigh a hundred pounds. They are either reflecting social norms or shaping them. You rarely see people with patterns of stress eating who are normal weight 

"Stress eaters should not be considered at risk to gain weight by default," says Sproesser. "Our results suggest the need for a dynamic view of food intake across multiple situations, positive and negative. Furthermore, our findings suggest rethinking the recommendation to regulate stress eating. Skipping food when being stressed may cause additional stress in munchers and could possibly disturb compensation across situations."