Colder temperatures and all the extra time we spend indoors during winter provide a good excuse to eat more, and indulge in a few extra glasses of wine. But does the weather really influence what we eat, or is it merely a fig leaf for our inherent gluttony?
The good news is that the dreaded winter coat is not inevitable. Changing energy demands for activities like hibernation, migration and reproduction among some mammals mean seasonal cycles of body weight are normal.
But the absence of some of these seasonal behaviours in humans, along with modern conveniences such artificial lighting and climate control, mean the influence of cold weather on our eating behaviours may be overstated.
When we look at the average body weight of adults between seasons, not all studies report a difference. In research reporting changes, the differences are actually quite small: between around 500 grams and two kilograms between summer and winter. (Post continues after gallery.)
But most of this research doesn’t tell us if the changes were actually increases in body fat (remember body mass comprises muscle, water, bone and fat).
However, one study of healthy Dutch adults reported waist circumference (a good measure of abdominal obesity) was higher in winter than in summer, among both men and women.
Research has produced mixed results on seasonal differences in diets among different groups of people. Some studies have not observed any daily energy intake changes with the seasons. Others have found that people tend to consume more kilojoules (calories) per day in the cooler seasons compared to warmer months.
A Spanish study of seasonal variations in food consumption, for instance, found intake of cereals and alcohol was higher among men in winter than in summer. But women had higher intakes of dairy foods, including ice-cream, in summer.
Fruit and vegetable intake also varied according to season, more likely due to seasonal availability.
Reflecting the findings about small weight increases in winter, research that has found changes in energy intake between seasons didn’t find a very big difference: the range was from 360 to 930kJ per day. This is roughly the equivalent of adding an extra roast potato at dinner, a few biscuits with your cup of tea or a couple of extra glasses of wine to what you’re already eating and drinking.