Well at home and with a glass of wine next to the computer , I did a few calculations on the energy efficiency of the human body.
It is generally accepted that, of the 2300 calories we need in a day, we use 60% of the energy for the basic metabolism (heart beat, respiration, keeping the body temperature), 30% for activities (moving, working, thinking) and 10% for digestion of the foodstuff. The excess above 2300 is stored as fat. This opens for a few interesting observations:
Increased physical activity will work only on the 30% of the daily expenditure. One hour at the gym will do very little for you on the overall daily energy expenditure (as it works only on the 30% of the total). Just as well to park oneself in front of the TV...honest, I'm not kidding!
Why not look for a strategy that addresses the 60% of the basic metabolism? Now, much of the basic metabolism aims at keeping us warm (I know, I’m just trying to keep it simple!). The metabolic reactions that help regulate body temperature will increase if we are in a cold environment, jut to keep us warm, or decrease if the environment is warm. On the other hand, we will also radiate heat if absolutely still, this is heat generated by chemical reactions in the body that aim at keeping us alive. Laboratory experiments have shown that in a warm environment (hot room or hot bath etc, no physical activity) we loose around 20 calories/hour as heat in order to avoid overheating. In a somewhat colder environment we will loose about 80 calories/hour (no physical activity).
Now, think of the situation hot bedroom and thick, Swiss style duvet.
In the one case (hot bedroom and duvet), the body uses up 20 Calories per hour for the 8 hours of sleep, or a total of around 160 Calories during the night. In the other case (thin covers, cool room) the body uses up the more natural 80 Calories per hour of sleep for those 8 hours or 640 Calories during the night. The difference of these two situations appears to be 480 Calories per night.
A pound of fat contains 3500 calories. Simple maths will tell you that you can loose a pound of fat every week if you put that duvet away, open the bedroom window and go to sleep!
Have a good night's sleep!