I am one of those people that had the good fortune to live in a number of different climates. I have noticed that as far as my fitness, form and mood are concerned, I tend to fair better in the summer and in warmer weather than I do in the winter in colder weather. Since I couldn’t help but notice the same difference in a number of other people I decided to research whether or not there are any reasons for this phenomenon that are not accounted for by lifestyle and eating habits. And indeed I found out that there are.
To begin with, I discovered the direct relationship between our vitamin D levels and obesity.
Researchers at the Medical College of Georgia studied 650 teens (aged 14-19). According to UPI, the teens “who reported higher vitamin D intakes had lower overall body fat and lower amounts of the fat in the abdomen.” Abdominal fat, also known as visceral fat (or belly fat), is associated with many unhealthy outcomes. These negative outcomes include hypertension, diabetes, stroke and heart disease. Plus, let’s face it: belly fat is the number one “extra” people would like to be rid of.
Not only did people with higher vitamin D blood levels have less overall fat, and less belly fat, other studies showed that good vitamin D levels helped adolescent girls gain muscle power. Vitamin D was even associated with being taller.
Via Wet Tub
Clearly colder climates tend to get less sunshine and vitamin D. Since vitamin D is a hormone, the above finding left me to wonder whether there are other hormones and compounds that we produce during the summer that we do not produce during winter. Hormones related to weight gain. This is what I found:
Skin temperature also affects growth hormone levels. In fact, simply taking a hot (38-39 degrees Celsius) bath for 25 minutes will raise growth hormone levels more than ten-fold.
A single surge in growth hormone increases both the number of fat calories your body burns for energy and your metabolic rate. That’s why growth hormone therapy often leads to a reduction in fat mass (but it doesn’t mean you can lose fat sitting in the bath — sorry).
Hibernating animals (those that sleep during the winter) tend to store fat before they hibernate. One of the ways they accomplish this is via an increase in the activity of enzymes (such as lipoprotein lipase, known also as LPL) that promote the storage of fat.
More interesting still, LPL levels in humans also rise and fall in tandem with the seasons. Researchers from the University of Colorado studied a group of 12 women and 6 men in both the summer and winter.
Summer was classed as May through August. Winter was classed as November through February. LPL activity in both muscle and fat increased during the winter, and dropped during the summer.
Winter also sees a change in the activity of several fat-burning and muscle-building hormones.
For example, cortisol levels reach a low point in the summer. Not only is cortisol associated with the storage of abdominal fat, it’s also been linked to all kinds of health problems, including diabetes, heart disease and depression. Cortisol may also weaken your immune system, leaving you more susceptible to colds and flu.
Testosterone, a powerful hormone which helps you build muscle and lose fat, tends to peak in the summer and early autumn. It also reaches a low point in the winter and early spring.
There’s also evidence to show that you’ll find it harder to control your appetite in the winter rather than the summer. Some studies, for instance, show a link between the “winter blues” and a drop in serotonin levels.
Serotonin is a chemical that helps messages pass from one nerve cell to another. It helps different parts of your brain “talk” to each other.
When serotonin drops below a certain level, your brain “thinks” that your body is starving and “tells” you to start eating. In fact, some researchers believe that there’s direct link between obesity (due to overeating) and decreased brain serotonin levels.
Overweight people with low levels of serotonin feel almost compelled to eat more. Once they get their carbohydrate “fix”, serotonin levels rise, and they feel better again — albeit temporarily.
To conclude I have to concede that cold climates often lead to shivering, and shivering expends calories. However this calorie expenditure is at best minimal. On the other hand less calories are burned when exercising in a cold climate because our heart and blood do not have to work overtime to cool off our skin when we get warm and start sweating.
Hence it is only natural to take on a little winter weight gain. The important thing is to shed it as Spring comes around. If not a couple of unshed pounds a year could eventually lead to obesity as the years go by.