By Tom Venuto,
First there's the psychological explanation: in warm climates, people are wearing less clothes and enjoying the outdoors and people want to look good when they're exposing more flesh! In the cold, you're covered up, so there's less self-consciousness and no public accountability. Therefore, most people tend to stay on a diet more diligently and train harder when summer rolls around.
Seasonal affective disorder (SAD) has been studied at length by psychologists. Often more than just the "winter blues" but an actual type of depression, SAD occurs during the short days and long nights of winter and fall, when there's less sunlight and colder temperatures. Symptoms include depression, cravings for specific foods, loss of energy, hopelessness and oversleeping. Obviously, these types of symptoms can contribute to weight gain.
Because of their tendency for fall and winter weight gain, many people have suspected that cold temperatures influence weight gain on a metabolic level, not just eating more. Exposure to cold temperatures can cause a shivering thermogenesis which means there's an increase in metabolism to produce more heat (heat production = calories burned).
However, if you just got the bright idea of turning off the heat in your house, or going for a swim in the cold surf every day to "burn more fat", I wouldn't recommend it. Deliberate exposure to the cold, either cold air or cold water doesn't pan out into real world fat loss results, even though there are actually "fat loss gurus" who recommend it.
If your body uses some energy for shivering or heat production, it can compensate later for that energy loss by increasing your appetite. Not only that, research at the hyperbaric environmental adaptation program at the Naval Medical Research Institute in Bethesda, Maryland reported that, "The combination of exercise and cold exposure does NOT act to enhance metabolism of fats . . . Cold-induced vasoconstriction of peripheral adipose tissue may account, in part, for the decrease in lipid mobilization."
It's just not practical to freeze your butt off in an attempt to speed up your metabolism a tiny little bit, so your fat loss scheme wouldn't last long if you tried.
A great example of how cold temperatures affect energy balance is in the case of swimming. For years, people thought swimming actually made you fat. There were all kinds of theories, like, "it makes you retain a layer of fat for insulation, like seals." Actually, the most recent research shows that swimming is a perfectly good fat burning exercise, except for one thing: Swimming, especially in cold water, increases appetite dramatically.
The seasons affect your activity levels too. Pedometer research published in the journal Medicine & Science in Sports & Exercise uncovered a huge difference in the number of steps taken between the summer and winter:
7616 steps per day in summer
6293 steps per day in fall
5304 steps per day in winter
5850 steps in spring
Most people blame winter weight gain on the food, but it's not just the Thanksgiving, Christmas and New Year's celebration feasts, it's less winter activity that also contributes to the holiday pounds.
You have to keep up your training and nutrition program in the winter, or else.
Although studies have found that seasonal weight gain is usually very small, it's the type of slow weight creep that goes unnoticed. Over a period of 10, 15 or 20 years, it's enough to accumulate into overweight or obesity.
Thus many men and women wake up one morning at age 40 or 45, look in the mirror and ask themselves, "How did I get so heavy?" Answer: just a pound or two a year, after each winter season, left unchecked.
To stay lean all year round, you have to remain alert about increases in your appetite and decreases in your activity. This is a YEAR-ROUND LIFESTYLE! Stay active, stay diligent about nutrition, stay accountable, and if you start to experience weight gain, nip it in the bud -- fast!
© 2010 Tom Venuto, author of The Body Fat Solution: Five Principles for Burning Fat, Building Lean Muscle, Ending Emotional Eating, and Maintaining Your Perfect Weight
Tom Venuto is a fat-loss expert, nutrition researcher, and natural, steroid-free bodybuilder. Since 1989, Venuto has been involved in virtually every aspect of the fitness and weight-loss industry -- as a personal trainer, nutrition consultant, motivation coach, fitness model, health club manager, and bestselling author of the popular e-book Burn the Fat, Feed the Muscle, as well as other digital programs such as MP3 teleseminars and weight-loss membership websites. He lives in Hoboken, New Jersey.