Prolonged psychological stress may negatively impact health, and has been cited as a factor in cognitive impairment with aging, depressive illness, and expression of disease.[60] Stress management is the application of methods to either reduce stress or increase tolerance to stress. Relaxation techniques are physical methods used to relieve stress. Psychological methods include cognitive therapy, meditation, and positive thinking, which work by reducing response to stress. Improving relevant skills, such as problem solving and time management skills, reduces uncertainty and builds confidence, which also reduces the reaction to stress-causing situations where those skills are applicable.
According to Tattvarthasutra, 2nd century CE Jain text, yoga is the sum of all the activities of mind, speech and body.[6] Umasvati calls yoga the cause of "asrava" or karmic influx[171] as well as one of the essentials—samyak caritra—in the path to liberation.[171] In his Niyamasara, Acarya Kundakunda, describes yoga bhakti—devotion to the path to liberation—as the highest form of devotion.[172] Acarya Haribhadra and Acarya Hemacandra mention the five major vows of ascetics and 12 minor vows of laity under yoga. This has led certain Indologists like Prof. Robert J. Zydenbos to call Jainism, essentially, a system of yogic thinking that grew into a full-fledged religion.[173] The five yamas or the constraints of the Yoga Sutras of Patanjali bear a resemblance to the five major vows of Jainism, indicating a history of strong cross-fertilization between these traditions.[173][note 16]
Yoga may have pre-Vedic elements.[45][46] Some state yoga originated in the Indus Valley Civilization.[51] Marshall,[52] Eliade[10] and other scholars note that the Pashupati seal discovered in an Indus Valley Civilization site depicts a figure in a position resembling an asana used for meditation, Mulabandhasana. This interpretation is considered speculative and uncertain by more recent analysis of Srinivasan[10] and may be a case of projecting "later practices into archeological findings".[53]
Social conditions such as poverty, social isolation and inability to get or prepare preferred foods can cause unintentional weight loss, and this may be particularly common in older people.[42] Nutrient intake can also be affected by culture, family and belief systems.[27] Ill-fitting dentures and other dental or oral health problems can also affect adequacy of nutrition.[27]
Ascetic practices, concentration and bodily postures described in the Vedas may have been precursors to yoga.[59][60] According to Geoffrey Samuel, "Our best evidence to date suggests that [yogic] practices developed in the same ascetic circles as the early sramana movements (Buddhists, Jainas and Ajivikas), probably in around the sixth and fifth centuries BCE."[9]
Intentional weight loss is the loss of total body mass as a result of efforts to improve fitness and health, or to change appearance through slimming. Weight loss in individuals who are overweight or obese can reduce health risks,[1] increase fitness,[2] and may delay the onset of diabetes.[1] It could reduce pain and increase movement in people with osteoarthritis of the knee.[2] Weight loss can lead to a reduction in hypertension (high blood pressure), however whether this reduces hypertension-related harm is unclear.[1][not in citation given]
Tantra is a range of esoteric traditions that began to arise in India no later than the 5th century CE.[180][note 17] George Samuel states, "Tantra" is a contested term, but may be considered as a school whose practices appeared in mostly complete form in Buddhist and Hindu texts by about 10th century CE.[182] Tantric texts include yogic techniques, as well as complex rituals, the use of mantras, devotion towards particular deities and various other practices. Tantric yoga developed complex visualizations which included meditation on the body as a microcosm of the cosmos. They included also the use of mantras, pranayama, and the manipulation of the subtle body, including its nadis and cakras. One of the most popular models of the Hindu tantric body is that of the Kubjikamata tantra (10th century), in which six power centers or cakras of the subtle body as seen as six forms of the goddess Kubjika and her consort. This tantra also contains a teaching on the goddess Kundalini, which resides at the base of the spine and through certain visualization exercises may be made to rise up through the central channel to the crown of the head where she is united with Siva. These teachings on cakras and Kundalini would become central to later forms of Indian Yoga.[183]
The first Hindu teacher to actively advocate and disseminate aspects of yoga, not including asanas, to a western audience, Swami Vivekananda, toured Europe and the United States in the 1890s.[204] The reception which Swami Vivekananda received built on the active interest of intellectuals, in particular the New England Transcendentalists, among them Ralph Waldo Emerson (1803–1882), who drew on German Romanticism and philosophers and scholars like G. W. F. Hegel (1770–1831), the brothers August Wilhelm Schlegel (1767–1845) and Karl Wilhelm Friedrich Schlegel (1772–1829), Max Mueller (1823–1900), Arthur Schopenhauer (1788–1860), and others who had (to varying degrees) interests in things Indian.[205][206]
The earliest references to hatha yoga are in Buddhist works dating from the eighth century.[197] The earliest definition of hatha yoga is found in the 11th century Buddhist text Vimalaprabha, which defines it in relation to the center channel, bindu etc.[198] Hatha yoga synthesizes elements of Patanjali's Yoga Sutras with posture and breathing exercises.[199] It marks the development of asanas (plural) into the full body 'postures' now in popular usage[15] and, along with its many modern variations, is the style that many people associate with the word yoga today.[200]
Public health has been described as "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals."[52] It is concerned with threats to the overall health of a community based on population health analysis. The population in question can be as small as a handful of people or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). Public health has many sub-fields, but typically includes the interdisciplinary categories of epidemiology, biostatistics and health services. Environmental health, community health, behavioral health, and occupational health are also important areas of public health.
Many governments view occupational health as a social challenge and have formed public organizations to ensure the health and safety of workers. Examples of these include the British Health and Safety Executive and in the United States, the National Institute for Occupational Safety and Health, which conducts research on occupational health and safety, and the Occupational Safety and Health Administration, which handles regulation and policy relating to worker safety and health.[63][64][65]

The number of asanas used in modern yoga has increased rapidly from a nominal 84 in 1830, as illustrated in Joga Pradipika, to some 200 in Light on Yoga and over 900 performed by Dharma Mittra by 1984. At the same time, the goals of Haṭha yoga, namely spiritual liberation (moksha) through the raising of kundalini energy, were largely replaced by the goals of fitness and relaxation, while many of Haṭha yoga's components like the shatkarmas (purifications), mudras (seals or gestures including the bandhas, locks to restrain the prana or vital principle), and pranayama were much reduced or removed entirely.[225] The term "hatha yoga" is also in use with a different meaning, a gentle unbranded yoga practice, independent of the major schools, sometimes mainly for women.[226]
In the UK, up to 5% of the general population is underweight, but more than 10% of those with lung or gastrointestinal diseases and who have recently had surgery.[29] According to data in the UK using the Malnutrition Universal Screening Tool ('MUST'), which incorporates unintentional weight loss, more than 10% of the population over the age of 65 is at risk of malnutrition.[29] A high proportion (10–60%) of hospital patients are also at risk, along with a similar proportion in care homes.[29]
Many patients will be in pain and have a loss of appetite after surgery.[25] Part of the body's response to surgery is to direct energy to wound healing, which increases the body's overall energy requirements.[25] Surgery affects nutritional status indirectly, particularly during the recovery period, as it can interfere with wound healing and other aspects of recovery.[25][29] Surgery directly affects nutritional status if a procedure permanently alters the digestive system.[25] Enteral nutrition (tube feeding) is often needed.[25] However a policy of 'nil by mouth' for all gastrointestinal surgery has not been shown to benefit, with some suggestion it might hinder recovery.[37][needs update]
The least intrusive weight loss methods, and those most often recommended, are adjustments to eating patterns and increased physical activity, generally in the form of exercise. The World Health Organization recommended that people combine a reduction of processed foods high in saturated fats, sugar and salt[10] and caloric content of the diet with an increase in physical activity.[11]