Combat changes in appetite, mood with exercise

Exercise during the winter helps elevate serotonin levels, experts say. The cold winter months can also bring about changes in appetite and mood, even though we don't hear as much about it.

It has been theorized that because fat is our bodies' natural insulator, we tend to eat more in the wintertime as a survival mechanism. While we know that too much body fat is unhealthy, it is true that individuals with greater amounts are better insulated against the cold and lose less heat than their leaner counterparts.

Researchers know that the hormone leptin, made by the body's fat cells, suppresses appetite while the hormone ghrelin signals the brain that you are hungry. It is believed that certain people may not process leptin as efficiently during cold winter months, increasing the likelihood of weight gain.

Although questions remain as to why this may occur, experts say that increasing the production of leptin can curb appetite and make you feel more full.

One way you can give your body more leptin is to get enough sleep. One study showed that participants had increased ghrelin levels, hunger and appetite when they got inadequate rest.

Along with producing a calming affect, the brain chemical serotonin is an appetite suppressant and can affect sleep and mood. If levels are too low or there is an imbalance between serotonin and other hormones, depression, food cravings and/or lack of quality sleep may occur.

It is not unusual for people with low serotonin levels to find themselves looking for an energy boost from coffee or other caffeinated beverages, drinking alcohol or craving foods like sugary snacks, potato chips or white-flour products.

Consuming these types of "emptycalorie" junk foods usually perpetuates the problem, leaving the person with an eventual "crash" a short time afterward. When this slump is felt, the cycle starts again, and the person will often look for another boost of energy.

In some individuals, low serotonin levels contribute to compulsive behaviors such as over-exercising, binge eating and/or drinking, which temporarily raise levels, or they may experience extreme feelings of anger or sadness.

Seasonal affective disorder (SAD) is a type of depression that most commonly begins in late fall and lasts through winter. It is believed that, because the body responds to seasonal changes in light, the lack of sunlight during winter months may create imbalances of hormones and brain chemicals, including serotonin.

In one study, production of serotonin by the brain was found to be lowest in winter and was strongly correlated with the amount of bright sunlight during the day. Other than bright sunlight, no other seasonal factors had an effect on serotonin production.

Scientists are still studying how environmental factors associated with the winter months may also contribute to SAD. Fortunately, healthy behaviors that help manage stress, such as yoga, meditation, massage, moderate physical activity and exposure to sunlight in limited amounts, have been associated with increased levels of serotonin.

Physical activity during winter months is especially helpful not only for weight management, but for keeping mood elevated because it increases production of the body's feel-good chemicals. Exercise also aids in regulating blood sugar, which can help control food cravings.

Marjie Gilliam is an International Sports Sciences Association Master certified personal trainer and fitness consultant.