Hard to believe, I know, but climate control can make us fatter. In a study published in the June 2006 edition of the International Journal of Obesity, University of Alabama at Birmingham, biostatistician Dr. David Allison suggested that air conditioning is one of 10 factors that may play an important role in today’s weight crisis. Dr. Allison showed a fascinating link between the huge proliferation of air conditioning in the southern U.S. and the higher prevalence of obesity in this region.
Changes in temperature, either up or down, can be perceived by your body as a stressor to which it must respond. This response requires energy and also influences our hormonal balance. For instance, when our body temperature drops, our sympathetic nervous system releases adrenalin, our blood vessels constrict to prevent heat loss (good for keeping us warm, not great for a glowing complexion in the long run) and we may also start to shiver. When we are hot, more blood flow is directed towards our skin to allow heat to radiate into our surroundings. Sympathetic stimulation causes us to start sweating, which also requires calories. In fact, I found one source noting a study showing that women who lived in a constant 80 degree climate burned almost 250 more calories per day at rest than women in a 70 degree environment.
Beyond the caloric expenditure involved in maintaining a constant core temperature, heat can help to control our weight by suppressing our appetite. An all-you-can-eat buffet certainly loses its appeal when we’re hot. But people living with constant climate control often fail to feel the heat. Now, don’t go cranking up your thermostat just yet. Heat does not work for long-term weight control because it tends to decrease our basal metabolic rate. When we’re constantly warm, less thyroid hormone is required to generate heat via our metabolism.
As we age, our natural ability to maintain and control our body temperature becomes less reliable. Our temperature also closely affects our sleep quality because we need to cool down slightly in order to properly activate the release of sleep-enhancing melatonin. We also know that sleep quality directly influences our body composition. Could poor temperature control be yet another reason for weight gain and hormonal imbalance as we age? I think so.
When it comes to sleep, the vast majority of my patients report experiencing far more restful nights after implementing the sleep rules from The Supercharged Hormone Diet. I have always thought these improvements were brought about by consistently balancing blood sugar, which helps to stabilize stress hormones (skipped and unbalanced meals raise cortisol). I am still certain that blood sugar balance plays a role, but I have also found a study in the Journal of Biorhythms (2002) that links melatonin production to the carbohydrate content of evening meals. After only three days of consuming carbohydrate-rich meals in the evening, salivary melatonin levels were reduced in otherwise healthy men. Less melatonin release, as we know, can cause sleep disruption and sleep disruption means more cravings for carbs.
Without realizing it, I was encouraging better melatonin release in my patients by recommending that they avoid high-carb dinners. What’s the link? Body temperature rises when we eat carbohydrates and stays elevated for about eight hours after consumption. The warmer we are, the less melatonin is released during sleep.
Alcohol also increases our night-time temperature, which could be another reason for its sleep-disrupting effects, besides its impact on our blood sugar and stress hormones. Researchers from France suggest this may also explain some clinical signs observed in alcoholic patients, including sleep and mood disorders. They go on to say that the negative effects of jet lag, shift work and aging—all of which are known to alter our body temperature by influencing our hormones—can be aggravated by alcohol. These factors can, therefore, affect our waistline too.
How can you use temperature to your hormonal advantage?
1.) Keep your house slightly cool in the winter and a little on the warmer side in the summer. These adjustments will increase the number of calories your body burns daily just to maintain its constant thermostat set point. They can also help stimulate thyroid hormone, so be sure your environment is not cold enough to boost your appetite.
During hotter months, avoid cranking up the air conditioning at night, so your body has to work just a bit harder to remain cool while you sleep.
2.) When our temperature increases, our appetite usually decreases. That said, activities that boost your body temp can be a nifty way to beat a craving. So instead of reaching for a fattening snack, have a hot shower, sit in the sunshine or do a quick set of push-ups to get your heat generators pumping.
3.) Supplements of chromium and 5 HTP can support the production of serotonin, which influences our body temperature, manages our mood and controls our cravings for carbohydrates or sweets.
4.) Finally, exercise in a room set at a comfortable temperature, around 68-75 degrees F (20–24 C). A workout environment that is too cold will interfere with your hormonal balance and could potentially reduce the fat-burning effects of your exercise sessions.