It is well documented and common knowledge than leading a sedentary lifestyle and consuming a diet that is rich in fat, sugar, and refined carbohydrates will inevitably lead to excessive weight gain over time.

In addition to having to carry the additional weight, which can contribute to decreased levels of energy, there have also been several medical studies that have linked several chronic and debilitating diseases to obesity.

While most individuals are aware that leading a sedentary lifestyle, coupled with poor eating habits, can lead to weight gain, did you know that there are numerous other things, ranging from diseases and illnesses to genes and medical operations, that can lead to weird weight gain as well?

By keeping yourself abreast of scientifically-proven factors related to weight gain, you will be empowered with the knowledge to avoid falling victim to them. Here are some of the strangest things that have been clinically proven to lead to excessive gain weight.

Strange Factors that can Cause Weight Gain

1. Catching Adenovirus 36

Sounds pretty obscure, right? Actually, adenovirus 36 is a one of many strains of the virus that causes the common cold. According to a study published in the medical journal Pediatrics, kids who have been exposed to adenovirus 36 could be up to 50 pounds overweight compared to kids not exposed to the virus. The study was conducted on 124 children, all of whom had been exposed, and 80% were found to be obese.

The take-away? Wash your hands often, avoid touching your face when in public places, and be especially careful about your hygiene during cold season.

2. Using Air Conditioning

According to an article published in the International Journal of Obesity, regularly living in an environment with comfortable temperatures can actually lead to weight loss. That’s because even when you’re sedentary, your body burns calories and effectively works itself out in order to adjust to the appropriate temperature.

The article pointed to the fact that 37% of homes in the South had air conditioning in 1978, a figure that swelled to 70% by 1997. Obesity rates in the same area raised commensurate with these statistics.

Of course, most individuals would prefer to be comfortable rather than miserable only for the sake of burning a few extra calories, and you should always try to work out in an environment with a comfortable temperature to keep from dehydrating faster than you expect.

3. Too Little Sleep

A recent study published in the Archives of Disease in Childhood suggests that a lack of sleep can increase your risk of obesity. When your body is sleep-deprived, it undergoes hormonal changes including glucose intolerance, something that can lead to diabetes.

Constantly being tired can make you eat more, and it can also cause you to put less thought into the types of foods you’re consuming. Further, not getting enough sleep could endanger your motivation for sticking with an exercise program.

4. Sleeping with the Lights On

If you’re tired all the time, you might be inclined to occasionally pass out without remembering to hit the lights. Unfortunately, that’s yet another thing that could be causing weird weight gain. A recent study posted in Proceedings of the National Academy of Sciences found that mice were susceptible to gaining approximately 50% more weight when they slept beneath a dim light instead of in complete darkness, despite having the same diet and exercise habits.

Although researchers aren’t exactly sure why this occurred, it’s likely that it has something to do with the ways in which our bodies metabolize food during sleep. If this is the case, then ensuring that all lights are off at night could be even more important for those who tend to eat late-night meals.

5. Pollution

Both the International Journal of Obesity and Critical Reviews in Food Science and Nutrition agree – pollution could have a significant effect on your metabolism. Chemicals such as polybrominated diphenyl and bisphenol A, a flame retardant and plastic ingredient, respectively, can interfere with the proper signals sent by your hormones, thereby increasing your chances of obesity. A wide variety of pesticides can travel up the food chain and end up in your body as well, resulting in the same effects.

6. Certain Medications

Drugs that are commonly used to treat or prevent hypertension, diabetes, depression and unwanted pregnancy can lead directly to weird weight gain, according to a recent study unveiled in Critical Reviews in Food Science and Nutrition.

A variety of Type 2 diabetes treatments and beta blockers, which are used to treat hypertension, have been associated with rapid weight gain. Psychotropic medications such as anti-depressants are becoming increasing popular, but you may want to think twice if your goal is to lose weight.

Numerous studies have shown that leading a healthier lifestyle that includes a balanced diet and regular exercise can reduce the symptoms of depression and increase your energy levels on their own.

Weird Weight Gain: The Bottom Line

It’s obvious that there’s more to weight loss than diet and exercise alone. The next time you’re struggling with your fitness regimen, ask yourself: Are you getting enough sleep, and making sure to turn the lights off before hitting the pillow? Are you doing your best to maintain sound hygiene, and staying healthy during cold and flu season?

Could your environment, including its temperature and air quality, have some effect on your weight? And finally, could some of your psychological ailments be treated through modifications to your diet and physical activity levels instead of with a pill?