IT’S easy at this time of year to put the feet up and shelter from the cold outside.
It’s almost as if we go into hibernation mode; a primitive adaptation to get us through the harsh winter months. Unfortunately, this lack of exercise usually coincides with a couple of weeks of dietary hedonism around Christmas and the New Year, with the imbalances in our calorie current account leaving us all carrying additional weight by the time January rolls in.
But while our straining waistbands are usually blamed on the dietary side of the equation — too much chocolate, booze, pudding, etc — very little consideration is given to the decline in physical activity levels at this time of year. The endless re-runs of Only Fools and Horses, the hours spent lazing in front of the fire and the leisurely lie-ins are all conspirators in this Christmas symphony of sloth.
For most people with reasonably active lifestyles, ignoring this seasonal drop in physical activity is a serious oversight. Though energy expenditure is notoriously difficult to measure accurately, we know that staying indoors for a few days in succession seriously decreases the amount of calories we burn.
The average daily energy expenditure for an adult woman is around 1,800 to 1,900 calories, while for the average man it’s about 2,400 to 2,500 calories.
Of these total calories, roughly 60-65% (1,100-1,600 calories) are used up by our basal functions — that is, the housekeeping metabolic activities that keep the heart, lungs, gut, brain and nervous systems running as they’re supposed to. The other 35-40% of our energy (600- 800 calories) is used up by discretionary physical activity, such as the energy we burn while walking around, eating, working and carrying out our other daily activities.
When you exercise, the energy burn from discretionary physical activity obviously increases. This might go up by 300 calories if you took in a brisk 45-minute walk, for example.
However, it’s not the only thing that changes, because the energy expenditure related to our basal functions also increases, usually by 10 to 15% for about 24 hours afterwards. This means that your 45-minute walk might yield a total calorie burn off of 450-500 calories each day. Unfortunately, the opposite also holds true — for every day that you’re idling over the Christmas break, you’ll be storing this 500 calories of energy, almost invariably as fat. So in simple energy terms, a ten-day hiatus in normal physical activity can prevent you burning around 5,000 calories.
This says nothing about the adverse metabolic changes that go hand in hand with low physical activity. For example, we know that lack of exercise increases insulin resistance.
This is bad news, because it means that we produce more insulin, and unfortunately this extra insulin primes our bodies to store fat. So not only are we supplying more calories (through dietary excess) and retaining more calories (through lack of activity), we’re also shifting our metabolism towards fat building. It is, the perfect storm in terms of weight gain.
The good news is that a bit of light exercise over the break can address two of these three main factors which lead to weight gain. By this I mean moderate intensity activity like a brisk walk for 30 to 40 minutes each day. It will also lift your mood and help make those indulgences a bit more forgiving if you do succumb to temptation on the dietary side.
Lovely jubbly, as Del-Boy might say.
* Dr Daniel McCartney, Lecturer in Human Nutrition & Dietetics at DIT
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