The link between sedentary behaviour and obesity is not straight forward because many research papers have demonstrated that increasing the energy expenditure of obese individuals with exercise does not cause long-term weight loss. Comparisons between developing and Western countries show that individuals from the latter have larger body sizes, but do not have reduced energy expenditure or reduced physical activity compared to the former. It is easy to assume that sedentary behaviour leads to obesity, but care should be taken to discern the type of activity and behaviours that might be associated with it. For example, watching television is associated with increased food consumption. However, it might not be the sedentary activity its self that causes obesity. Research has shown that instead it might be the exposure to advertisements about food that increases energy intake in susceptible individuals (here).
Researchers1 have also investigated the effects of playing a solitaire based computer game during a fixed lunch on memory for the food and subsequent food intake. Subjects were split into two groups, one group was fed lunch at a fixed rate with no distraction, while the other group was fed an identical meal at the same fixed rate, but were distracted by having to play the computer game. The results showed that those subjects who had been distracted were less full after lunch compared to the control (no distraction) group. In a subsequent taste test which was timed 30 minutes after the initial lunch, subjects from the distracted group ate more biscuits than the control group (52.1 grams versus 27.1 grams, respectively). The memory of the 9 items fed at lunch was also less accurate in the group of subjects that had been distracted when compared to the non-distracted group.
These results suggest that memory of eating may play some role in subsequent food intake. Distraction during eating caused subjects to consume 100% more food at a subsequent meal, which may suggest appetite regulation outside of the normal neuronal and hormonal mechanisms. These results also support the previous findings of the only other study to look at meal distraction, which found similar increased consumption 2.5 hours after being distracted. These finding may be explained by the fact that the subjects had weakened visceral sensations from eating, or alternatively perhaps the distraction interfered with the subject’s ability to interpret these feelings. Evidence from this study therefore suggests that memory plays an important role is producing a feeling of satiety. Eating while being distracted, as is common in modern living, may contribute to obesity.