Pizza Party Perils: Does your metabolism have to slow down as you get older?

Part of getting older is not being able to eat all the crazy things you did as a kid. While teenagers may be able to eat an entire pizza in one sitting without showing any adverse effects, it is common knowledge that as we get older our metabolisms slow down and we put on weight more easily… But what if that wasn’t actually true?

To understand what I’m talking about you need to understand what the word metabolism actually means. Your body is a busy place. Even when you are sitting on the couch or laying in bed catching up on your favourite illustrated science blog, your body is hard at work doing a million different things. Blood is pumping though your veins, the muscles in your chest and diaphragm are flexing to pull air into your lungs, the synapses in your brain are firing at a rate that is hard you fully comprehend; and all of this requires energy. Your metabolism is just a measure of how effectively your body turns the food you eat into the energy you need to function.

A lot of things can impact your basal metabolic rate (the amount of energy your body uses to do all the basic functioning I just mentioned). Surprisingly, though, there isn’t as much variability as you might think. Many people claim to have a slow metabolism, but this is actual a pretty rare thing and is usually caused by an underlying medical condition like hypothyroidism or Cushing’s Disease. In truth, the big things that impact your metabolism are your sex and body composition.

Generally speaking men have less body fat than women and more of their weight is comprised of muscle mass. Even at rest, muscle burns more calories than fat so men tend to require more energy just to maintain a basic level of function. While you may not be able to control your sex, you have a measure more control over your body composition (within reason). People who lift weights can increase the proportion of their body weight that is muscle and thereby burn more calories. That is what is meant by body composition. Your age can work to slow down your metabolism, but only if you allow your muscle mass to decrease. Go to any master’s (over 40) track and field meet and you will find a whole suite of people who maintain speedy metabolisms simply by continuing to exercise and not letting their muscles deteriorate.

Particularly intense exercise has the added bonus of keeping your metabolism elevated for a period of time after you are done your workout. Known as “excess post-exercise oxygen consumption” (EPOC), the phenomenon is caused by the recovery processes taking place after a hard day at the gym or the track. A recent swath of articles in the fitness world with a surprising amount of science behind them argue that as you increase the intensity of a workout, you can get the same physical benefits of working out at an easier level for much much longer. Some have even suggested that if you run hard enough, 5 minutes a day can give you all the benefits of running slowly for an hour or more.

But If exercise isn’t your thing and you want to boost your metabolism anyway, there are options. One of the best is nicotine, which speeds up your heart rate and forces your body to burn more calories. The Mayo clinic suggests that smoking 20 cigarettes per day is roughly equivalent to putting on 90 lbs in terms of increase to your metabolic rate. (Contrary to popular thought, fatter people actually have faster metabolisms than skinnier people with the same activity level because it takes more energy to move blood around their bodies and they are likely to have more muscle mass.) Obviously nicotine has its drawbacks if you enjoy being alive and hope to continue in an animated state for a long period of time, but if all you’re going for is metabolic speed, it will help.

But even with the help of devastatingly harmful drugs and all the exercise we can handle, humans are wimps in terms of metabolic flexibility. Many animals can put us to shame. Bears in particular are masters of metabolism. Research has suggested that during their winter rest period (not technically hibernation) bears can reduce their metabolic rates by 75%. The net effect is reducing their body temperature by up to 6 degrees! In humans, that is grounds for hospitalization, but the bears manage it just fine. They don’t fully warm up again until up to three weeks after leaving their dens.

So in the end, you metabolism may not be an entirely changeable thing. But next time someone tries you give you spin about your metabolism slowing down with age, set them straight and tell them to hit the gym.

Sketchy Fact #46: Stale Clams

In 2006 a clam from the species Arctica islandica was collected and killed for climate change research of the coast of Ireland. Researchers studying the clam felt surprised and probably a little guilty when they discovered the clam was 507 years old. The oldest complex animal ever found.

Sketchy Fact #43: Elderly Disparity

According to the World Health Organization, the average life expectancy for a Japanese woman hit 87 years old in 2012. In Sierra Leone it rose to 46.

Deficient in Daylight: Why is Late January Such a Bummer?

If you’ve been feeling a little down this week odds are you are not alone. The third week of January and the third Monday of the year in particular is apparently the most depressing time of the year. “Blue Monday” as has come to be known was first publicized eight years ago by psychologist Cliff Arnall as part of a press release for a British travel agency. In spite of the obvious ulterior motives associated with the message and the medium, most of us would agree that the idea isn’t completely off base. 

The explanation offered by Arnall posited a number of culprits we could blame for the late January blues: feeling poor after Christmas, the fresh sting of failed New Year’s Resolutions, and decreased daylight hours just to name a few. Whether or not money and failure factor into it, there is certainly something to the idea that exposure to sunlight can impact our moods. A British survey reported that 79% of people feel that reduced daylight hours during the winter in temperate climates has a negative effect on their mental constitution.

Your body is not much more than a machine and your brain (as much as we like to put it on a pedestal) is just another piece of the puzzle. Just like with a car, the things our bodies are exposed to have a profound effect on the way that they function. Researchers at Johns Hopkins University have reported that altering the brain’s exposure to light throughout the day can increase levels of stress hormones in the body, impair sleep, and lead to a deficit in mental agility. 

Their study used mice and actually involved exposing them to light when their bodies were expecting darkness, but the results certainly highlight the vulnerability of the brain to changes in brightness. Their mice also quickly began to demonstrate behaviours associated with depression. Before you ask, a depressed mouse shows reduced movement and lack of interest in sugar and other pleasure seeking activities. While a depressed person might pursue sugar more actively than a happy one, the parallels are still striking. 

The reason for the changes brought on by light can be traced back to the body’s biological clock and the daily patterns of wakefulness and sleep that tend to correspond with light and darkness. These natural fluctuations are known as circadian rhythms and they have a profound impact on the behaviour of all living things. While we are probably most familiar with the daily rhythms of our own bodies, changes also occur on the scale of seasons and years. As we grow up, we are most active at different times of the day. A five year old might wake up at the crack of dawn to watch cartoons while his parents don’t rise until mid-morning and his teenaged sister doesn’t begin to stir until just before dinner. 

Likewise, seasonal changes impact the way we behave. Many animal species are thought to begin their annual migrations in response to changes in the length of the day and even the angle of the sun. Similarly, we humans are subject to the suns whims. Part of the explanation for why we don’t deal with the changes as well as butterflies, birds, and caribou could be that we evolved as an equatorial species and our internal clocks aren’t quite built for the huge swings in sunlight hours seen at more extreme latitudes. To put it on a more comprehensible time scale, a person from Hawaii might have a hard time dealing with 20+ hours of night in the extreme north if you suddenly dropped them in Iqaluit. 

There are a number of things we can do to combat the winter blues, however. Sitting near windows can help us make the most of the daylight available and exercising for a few minutes each day can help get mood enhancing chemicals flowing in your body and brain. For the exceptionally lazy, there are even special lights you can buy to help trick your body into thinking the sun is still up. However you cope, it helps to know that the sadness you feel isn’t actually related to the things going on in your life. Remember, we’re all in this together… except for the Hawaiians I guess.