Whether that means eating unhealthy foods, or foods that lack enough calories for your body, both can lead to low immunity.
http://health.allwomenstalk.com/hidden-signs-of-depression-y...
Sleep deprivation may lead to decreased immunity
http://www.1-800homeopathy.com/news/article/read/sleep/sleep...

Weakened Immune System - Symptoms, Diagnosis, Treatment and ...
";www.diagnose-me.com/symptoms-of/weakened-immune-system.html
Jump to What else it can lead to - Weakened Immune System can lead to: Infections. Weakened Immune System sometimes leads to West Nile Virus ..."

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Note added at 22 hrs (2014-06-20 16:36:09 GMT)
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11 things that can weaken your immune system - Rediff Getahead
www.rediff.com › Getahead
"- Obesity can lead to a weakened immune system. It can affect the ability of white blood cells to multiply, produce antibodies, and prevent ..."

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Note added at 22 hrs (2014-06-20 16:37:19 GMT)
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Fatty food can weaken the immune system -- ScienceDaily
www.sciencedaily.com/releases/2009/12/091208132526.htm
-"Obesity is usually associated with inflammation that does not result from an infection, which simply means that the immune defences are ."

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Note added at 22 hrs (2014-06-20 16:38:20 GMT)
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Understanding Pneumonia - American Lung Association
www.lung.org › Lung Disease › Pneumonia
"Many small germs, such as bacteria, viruses, and fungi, can cause pneumonia. ... diseases or viral infections and people who have weakened immune systems."