Yoga is one of the richest heritages of India. It is both a philosophy as well as a practical science of healthy living. The scientific aspects of yoga are now being extensively investigated all over the world, and the efficacy of yoga therapy is well established, particularly in the treatment of various diseases like asthma, diabetes, obesity, heart disease and various nervous and mental disorders.
At the Lokmanya Municipal General Hospital, Sion, Bombay, we have studied the effect of yoga therapy in 52 diabetic cases and 38 obese subjects, from both the young and middle age groups. Individuals over the age of 55, and those with heart, liver, kidney, bone or joint diseases, were excluded for obvious reasons. Our experiences are given in this article for the benefit of yoga students.
The therapy consisted of first introducing the principles of yoga philosophy, and then the teaching of simple asanas in groups, under the supervision of experts. The participants were asked to practise at home, for half an hour per day. The following asanas were taught: padmasana, veerasana, paschimottanasana, padangushthasana, trikonasana, janusirshasana, L pose (preliminary to sarvangasana), tadasana, shavasana, nauli. Other asanas, and kumbhaka, were advised for those who were lean and young, and without any physical handicaps.
The purpose of these asanas was to make the patients contract and relax muscles slowly, especially those of the abdomen. Alternate expansion and compression of abdominal viscera, and an increase in abdominal pressure, were presumed to increase blood circulation and promote the function of liver, pancreas and other internal organs.
Out of 52 subjects, weight loss was seen in 37 subjects. After 6 months' treatment weight loss ranged from 2 to 4 kg. The after-lunch blood sugar showed a distinct fall to near normal levels, requiring considerable reduction in dose of drugs like insulin or oral tablets. In two patients, drugs had to be discontinued. Lowering of blood fats (cholesterol) was seen in 20 cases.
After yoga therapy, all subjects felt relief of symptoms like tension, headache, constipation, dyspepsia, etc. Many had a feeling of exhilaration, lightness and suppleness of body. However, some did complain initially of muscle and joint pains until they could do the asanas more easily. It may be noted here that before yoga therapy all these subjects were taking anti-diabetic drugs and observing dietary restrictions. But addition of yoga therapy showed a substantial and significant benefit. The diet and drugs were not discontinued.
Similar beneficial results have been reported in India by Melkote (1973), Varandani (1973), and Rukmini and Sinha (1975), at the seminars on yoga sponsored by the Central Council for Research in Indian Medicine in 1973 and 1975. In normal young volunteers, after doing hatha yoga, blood sugar has been reported to be lowered (Udupa et al., 1972). In their therapy, they adopted mudras and shatkarmas (cleansing procedures). We did not give these in our trial, as they were time consuming and were not found necessary.
It may be said that yoga therapy is nothing but physical suppleness and mental relaxation. However, medical research now indicates that yoga may act directly on the central nervous system, the blood circulation and the metabolism.
Our patients, at the end of 30 minutes of yoga therapy, did not feel tired or exhausted. On the contrary, they felt relaxed, when they did it in the right manner. Yogasanas are postures, not exercises, which involve slow and rhythmic contraction and relaxation of muscles, and deeper and slower breathing, all of which tend to improve circulation and lung ventilation.
Yoga is basically designed to train or to control the autonomic or involuntary nervous system through activation of the hypothalamus. The hypothalamus is a part of the brain which controls hunger, sleep and emotions, as well as endocrine glands like the pituitary, thyroid, pancreas and suprarenal glands. It also plays a role in control of hunger and appetite and is thus directly connected with increase or decrease in body weight.
Although diabetes is due to relative or absolute deficiency of insulin, the basic cause may not necessarily lie only in the pancreas, or the extra pancreatic areas. The central nervous system has a definite role to play by maintaining equilibrium between the involuntary parasympathetic and sympathetic systems. Disequilibrium of the autonomic nervous system is reflected in emotional disturbance, which is known to upset weight, control of diabetes and blood glucose levels. This may be caused by excess secretion of epinephrine, leading to diminished secretion of insulin and subsequent metabolic disturbances.
The scientific proof that the hypothalamus can be influenced by classical conditioning (as in meditation) has come from biofeedback observations using appropriate instruments (Shapiro, 1969). Recently Stone and De Leo (1969), working on high blood pressure cases, have shown that an enzymatic substance called dopamine-beta-hydroxylase (DBH) is reduced in the hypothalamic area after yoga and relaxation. The reduction of this enzyme reduces peripheral epinephrine activity in response to emotions and other stimuli and helps to reduce blood pressure and blood sugar. Yoga-induced hypothalamic changes would also influence endocrine functions which in their turn control metabolism. This is one scientific explanation of yoga therapy.
Another way in which yoga perhaps acts is through a physical mechanism. There may be a direct stimulatory effect on the circulation in the digestive organs of the abdomen, such as the liver, pancreas, stomach, etc. Alternate contraction and relaxation of abdominal muscles has a kind of pumping action on both arterial and venous blood vessels. It is also likely that there may be increased utilisation of glucose in muscles and dissipation of fats for energy. This view is purely conjectural and needs to be substantiated by scientific proof.
In conclusion, after yoga therapy there is a definite improvement in control of blood glucose and diabetes and also reduction in weight. However, this does not necessarily allow the individual to abandon dietetic restrictions or drugs. Yoga therapy acts (i) by controlling the autonomic or involuntary system in the hypothalamus and (ii) perhaps by improvement in the blood circulation in the digestive organs, through alternate contraction and relaxation of abdominal muscles. This, however, remains to be verified.