Can thinking make you fat?

October 19, 2008

As someone who spends at least 80% of her waking hours with the brain on full alert, I found this news item a bit worrying. Apparently a research team has demonstrated that intellectual work can lead to a substantial increase in appetite and, therefore, calorie intake. After a hard day of mental work, you can be just as physically exhausted as if you had spent the day doing physical work – just ask my cats if you don’t believe me.

A small study of 14 students were given three tasks: relaxing in a sitting position, reading and summarizing a text, and completing a series of memory, attention, and vigilance tests on the computer. Although the intellectual work required only three calories more than the rest period, the students consumed 203 more calories after summarizing a text and 253 more calories after the computer tests than they did after relaxing.

Blood samples taken before, during, and after each session revealed that intellectual work caused bigger fluctuations in glucose and insulin levels, effectively destabilising the levels of insulin and glucose. This in turn stimulates the appetite, apparently in response to a need to restore the body’s energy balance, though why it always has to be with chocolate biscuits (or is that just me?) science has yet to explain.

Now, if you do a lot of mentally challenging tasks it’s a good idea to eat plenty of the foods that are known to nourish your brain. From what we know about brain-boosting foods, the ideal post-thinking snack would seem to be a chicken and spinach omelette with a cup of green tea – but I don’t see many students opting for that!


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