It has always been taken for granted that eating fast makes us put on weight. This idea stems from the hypothesis that by eating fast, satiety signals will arrive late to our brain, when we have already eaten more food than we would really need to feel satiated. But is this true?

The existence of an “obese eating style,” characterized by a rapid rate of food intake with large, frequent bites and short meal durations, was first promoted by Ferster in 1961. He suggested that obese people eat faster than lean people.

From there, behavioral prescriptions aimed at decreasing bite size, slowing the rate of food intake, and lengthening the duration of meals were developed. Over the past two decades, experiments have been conducted to compare the eating patterns of obese and non-obese individuals, but the results have been contradictory. In fact, the relationship between speed of food intake and overweight derived from observational studies in poorly controlled laboratory settings or in public eating establishments. Most studies also draw conclusions from a single meal and not from daily or weekly observations. Therefore, the existence of a (misnamed), “obese eating style” cannot be confirmed.

However, in one study (Rising et al 1994) the relationship between ad libitum food intake rate and obesity was assessed in 28 men over 4 days in a metabolic ward (highly controlled). The mean duration of meals was 25 minutes. The rate of food intake was 68 grams/minute.

The conclusion was that subjects with obesity ate more slowly than subjects without obesity. That is, contrary to what was thought. The slower rate of food intake results in a lower degree of meal-induced gastrointestinal distention. Gastric distension is a mechanism that modulates food intake (satiety), for example through ghrelin. Further studies are required.