A sedentary lifestyle is a type of lifestyle with little or no physical activity. A person living a sedentary lifestyle is often sitting or lying down while engaged in an activity like reading, socializing, watching television, playing video games, or using a mobile phone/ computer for much of the day. A sedentary lifestyle can potentially contribute to ill health and many preventable causes of death.
Screen time is a modern term for the amount of time a person spends looking at a screen such as a television, computer monitor, or mobile device. Excessive screen time is linked to negative health consequences.    
Lack of exercise causes muscle atrophy, i.e. shrinking and weakening of the muscles, and accordingly increases susceptibility to physical injury. Additionally, physical fitness is correlated with immune system function;  a reduction in physical fitness is generally accompanied by a weakening of the immune system. A review in Nature Reviews Cardiology suggests that since illness or injury are associated with prolonged periods of enforced rest, such sedentariness has physiologically become linked to life-preserving metabolic and stress related responses such as inflammation that aid recovery during illness and injury but which due to being nonadaptive during health now lead to chronic diseases. 
In the United States, total calorie intake by children and adolescents increased in the 1990s and early 2000s. Sweetened beverages, grain-based desserts, breads, and pizza were among the main contributors to this total calorie increase.  These foods are high in sugar and fats, and are typically low in nutrient content. The 2015 - 2020 Dietary Guidelines recommend limiting these foods for their low nutrient content. 
In 2008, the United States American National Health Interview Survey found that 36% of adults were inactive, and 59% of adult respondents never participated in vigorous physical activity lasting more than 10 minutes per week.  Over the last hundred years, there has been a large shift from manual labor jobs (e.g. farming, manufacturing, building) to office jobs which is due to many contributing factors including globalization, outsourcing of jobs and technological advances (specifically internet and computers). From 1990 to 2016, there has been a decrease of about one third in manual labor jobs/employment.  In 1960 there was a huge decline of jobs requiring moderate physical activity from 50% to 20%. In addition, as study was conducted by the New York Times which concluded that in 1960 1 in 2 Americans had a physically demanding job while in 2011 this ratio is now 1 in 5.  This shift in office jobs now tend to require even longer days of sitting either at a desk, in meetings or even for meals. According to a 2018 study, office based workers typically spend 70-85% sitting.  which can be a direct cause to obesity due to the known research that lack of movement leads to slower metabolism, with food and fat being accumulated in the body instead of burned for energy  This can really take into effect when people begin eating at their desks for lunch instead of walking from one's job to get food. In turn, this increased amount of sitting, long days at work, and lack of physical activity has had an impact on health and BMI. 
Effects of a sedentary work life or lifestyle can be either direct or indirect. One of the most prominent direct effect of a sedentary lifestyle is an increased BMI leading to obesity. A lack of physical activity is one of the leading causes of preventable death worldwide. 
At least 300,000 premature deaths, and $90 billion in direct healthcare costs are caused by obesity and sedentary lifestyle per year in the US alone.  The risk is higher among those that sit still more than 5 hours per day. It is shown to be a risk factor on its own independent of hard exercise and BMI. People that sit still more than 4 hours per day have a 40 percent higher risk than those that sit fewer than 4 hours per day. However, those that exercise at least 4 hours per week are as healthy as those that sit fewer than 4 hours per day.  
Indirectly, an increased BMI due to a sedentary lifestyle can lead to decreased productivity and increased absenteeism from necessary activities like work.  Missing work and not being productive results in obvious short term and long term effects like less income and job security.
A sedentary lifestyle and lack of physical activity can contribute to or be a risk factor for:
- Anxiety  
- Cardiovascular disease 
- Breast cancer
- Colon cancer 
- Computer vision syndrome only for computers and tablets
- Depression  
- Diabetes 
- High blood pressure  
- Lipid disorders 
- Skin problems such as hair loss[ citation needed]
- Mortality in adults  
- Obesity  
- Osteoporosis   
- Scoliosis   
- Spinal disc herniation ( low back pain) 
As a response to concerns over health and environmental issues, some organizations have promoted active travel, which seeks to promote walking and cycling as safe and attractive alternatives to motorized transport.  Additionally, some organizations have implemented exercise classes at lunch, walking challenges among co-workers, or allowing employees to stand rather than sit at their desk during the workday. Workplace interventions such as alternative activity workstations, sit-stand desks, promotion of stair use are among measures being implemented to counter the harms of sedentary workplace environments.  A Cochrane systematic review published in 2016 concluded that "at present there is very low quality evidence that sit-stand desks can reduce sitting at work at the short term. There is no evidence for other types of interventions." Also, evidence was lacking on the long term health benefits of such interventions. [ needs update] Similarly a recently published review concluded that interventions aimed at reducing sitting outside of work were only modestly effective.  Organizations may also offer cholesterol or blood pressure screenings to employees. 
Workplace initiatives are practices and programs sponsored by employers to promote employee health, and in turn, reduce insurance costs for the employer. Multiple studies have been done on the effectiveness of healthy workplace initiative programs. Programs can be focused on either weight reduction, or prevention of further weight gain and may include a wide variety of methods such as health care screenings, smoking cessation programs, discounted gym/fitness memberships, ergonomic controls (standing desks, ergonomic keyboards), wellness classes, providing healthy food at meetings and employee events, stocking vending machines with healthy options, and surgical intervention. Due to the wide variety of work environments, and inconsistent habits and lifestyles of individuals across different workplaces, these studies have not been conclusive regarding the effectiveness of these type of programs on BMI . However, other associations have been linked between workplace initiatives and outcomes such as increased work productivity or a decrease in the amount of sick days .
- 9 to 5
- Active transportation
- Childhood obesity
- Exercise trends
- Neurobiological effects of physical exercise
- Simple living
- Sloth (deadly sin)
- Lack of physical education
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