This week I’ve been reading about temptation; in particular, how gender impacts on our propensity to be tempted by food and, as a result, how it can influence our weight loss goals.
I started to think about this while reading about the ways in which gender can affect how our bodies process various chemicals – caffeine, alcohol, medications etc. Variants including body mass, height, muscle to adipose tissue ratios and hormones all influence the ways that we process these chemicals, and with some medications this can lead variance in the efficacy and the side effects (for more on this watch this TED talk by Alyson McGregor). While even taking the contraceptive pill can influence how we metabolise caffeine.
But how does gender impact on how we respond to food? Are differentials contingent on metabolic and digestive reactions alone or can differing successes between men and women in the weight-loss steaks be attributed to something else?
While considering this I encountered a rather interesting study from Brookhaven National Laboratory, which looked at the ways in which our brains respond in the presence of food.
In the study, 23 healthy male and female volunteers were instructed to fast for a 17 hour period. During this time, they were interviewed about their favourite foods and asked to rank them on a scale of 1 to 10. The researchers then selected one food for each subject, the only requirement being that it scored 7 or above in desirability. When the 17 hours were up, the volunteers were injected with a nuclear tracer, placed in a brain-imaging PET scanner and presented with a food they craved – being forced to smell, hear about the preparation of and even taste a morsel of the food stuff on a cotton wool ball.
When faced by this multi-sensory stimuli, the brains of the fasted volunteers started responding. Appetite and hunger are processed in a number of regions of the brain — most notably the orbital frontal cortex, which is linked to self-control; the striatum, which is linked to motivation; the hippocampus, which is linked to memory; and the amygdala, which is linked to emotions and decision making.
The subjects were then asked to think about something other than food for the next 40 minutes, though they were required to keep their eyes open and look at the food before them.
The PET scans appeared to show that both sexes were actually able to lower the overall sensation of hunger; in most cases the brain was able to grow partially habituated to an empty stomach over time, and with a degree of willpower and distraction, the volunteers were able to hasten this process of desensitisation.
However, the discrepancy came with what men and women thought about during this time. It appeared that while the men were able to stop thinking about food, successfully suppressing, if only temporarily, the conscious desire to eat, the women continued to experience emotional cravings even if their hunger subsided.
Although it is unclear what is behind this difference, it is suggested that hormones and their action on the amygdala may play a significant role. When the amygdala acts up it is incredibly difficult to bring it back under control – demonstrable in anxiety conditions like phobias and obsessive-compulsive disorders, which are linked back to this part of the brain. The study suggests however, that men had some success in disciplining their amygdala, while women were less able to do this. However, it takes a lot of inhibition to control the amygdala, which is why even the most resolute dieters — both male and female — so often fail.
Although this study only used a small sample it is an interesting insight into how we respond to and think about food. In the next post, I’ll be looking at some ways to tackle temptation, but for now, happy resisting!