Many people who come to see me for weight loss counselling have been dieting for years. And they are frustrated. They have learned the hard way that dieting just doesn’t work over the long term.

Dieting interferes with internal signals for hunger and fullness that are necessary for normal healthy eating. This was illustrated in a study done at the University of Toronto which took a group of dieters and a group of nondieters and gave them the task of comparing ice cream flavors.

Participants in each group were divided into three subgroups. Before getting the ice cream, the first subgroup was asked to drink two milkshakes, the second subgroup was asked to drink one milkshake, and the third subgroup wasn’t given any milkshakes. Next, the researchers offered the groups three flavors of ice cream and asked the participants to rate the flavors, eating as much ice cream as they desired.

The results revealed that the nondieters ate according to their inner hunger and satiety cues.  Those who hadn’t had any milkshakes ate the most ice cream, those who’d consumed one milkshake ate less ice cream, and those who’d consumed two milkshakes ate the least.

The dieters, however, reacted in the opposite way. Those who were offered no milkshakes before the taste test ate small amounts of ice cream, those who drank one shake ate more ice cream, and those who’d consumed two milkshakes ate the most ice cream!

This phenomena is called “disinhibition” and it becomes part of the diet mentality pretty quickly.  Nondieters, eating in an unrestrained and normal manner, tend to regulate their food intake according to internal physical cues of hunger and satiety.

The dieters, however, reacted in the opposite way—the more milkshakes they consumed, the more ice cream they ate. According to the researchers, this “counterregulation” occurs because a milkshake preload disinhibits a dieter’s usually inhibited or restrained eating, almost like a switch: “I’ve blown it anyway, so I might as well keep eating before I go back on my diet.”