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Yoga for Weight Loss
By Judith L. Balk, MD. Dr. Balk is Associate Professor, Magee-Women's Hospital, University of Pittsburgh; she reports no financial relationship to this field of study.
Synopsis: Weight loss and weight maintenance are often difficult to achieve. Although exercise is recommended as one of the mainstays of treatment, many overweight people have difficulty finding a feasible and enjoyable form of exercise. Yoga, with its physical postures, breathing techniques, relaxation training, and nonreactive mindset, may be an effective approach to help with weight loss. This article summarizes the evidence for yoga as part of a weight management regimen.
Health care costs are higher for obese patients than for non-obese patients, in part due to higher use of conventional medical care.1 However, effective medical treatments for obesity are limited, so one might postulate that obese patients would be more likely to try complementary and alternative medical (CAM) approaches for treatment of obesity. However, one large survey, the National Health Interview Survey, compared the use of CAM between normal-weight individuals and those who are overweight, mildly obese, moderately obese, and extremely obese.1 Although obese adults have greater illness burden and higher utilization of traditional medical care, they are not more likely to use CAM approaches. Obese adults have a similar prevalence of CAM modality use, including relaxation techniques, botanicals, massage, chiropractic, and acupuncture. Interestingly, tai chi was as commonly used in obese as in normal-weight individuals, but adults with obesity have a lower prevalence of the use of yoga. This cross-sectional survey does not indicate whether those who are obese choose not to do yoga, or whether yoga effectively treats obesity, but it does indicate an inverse association between obesity and the use of yoga. Some forms of yoga may also be difficult due to an obese body habitus.
On a very basic level, weight gain is due to higher caloric intake relative to lower caloric expenditure, although many other factors are important, such as the quality/type of the calories. When considering both caloric intake and expenditure, the two most important factors are diet and exercise. However, diet and exercise have many component factors, and obesity is considered to be multifactorial. For instance, genetic predisposition, sedentary lifestyle, overeating, fast food diet, increased portion size, and marketing of unhealthy foods all may play a role in obesity.2 A seemingly "simple" recommendation is to reduce energy intake and to increase energy expenditure. However, this "simple" recommendation is difficult to implement, especially when one is overweight, because energy expenditure, for instance exercise, can be difficult. A holistic approach, such as yoga, that promotes energy expenditure while reducing energy intake may be effective for weight loss. Interestingly, long-term yoga practitioners at a residential yoga center in Bangalore had a lower basal metabolic rate compared to non-yoga practitioners with similar lifestyles.3 This lower metabolic rate may be due to reduced overall arousal, although basal metabolic rate adapts to the nutritional status and physical activity of the individual. No evidence suggests that a casual yoga student lowers his or her metabolic rate; perhaps yoga practitioners who have chosen to live in a residential yoga center have chronically lowered metabolic rates due to chronically low stress.
Hatha yoga is a combination of breathing exercises (pranayama), relaxation techniques, and physical postures (asanas). Yoga also may include various lifestyle guidelines such as vegetarianism and clean eating. Thus, yoga practitioners may choose food that is of higher quality. Yoga is historically considered to help reduce stress, increase mindfulness, and improve fitness, flexibility, and mood.2 Obesity and overweight may be reduced with improved stress coping by reducing emotional eating. Similarly, mindful eating may reduce overall caloric intake, and improved fitness may increase caloric expenditure. In addition, yoga indirectly may improve body weight via its emphasis on developing body awareness and physical discipline.4 Yoga practitioners consistently note that they feel "more connected" to their bodies4; overeating may then be more uncomfortable for one who is more aware of bodily sensations. Thus, it is possible that yoga could decrease weight. However, little rigorous research has been published specifically on yoga for weight loss.
Mindfulness is described as nonjudgmental awareness of the present moment, and it is associated with many positive health outcomes.5 Specifically for obesity, mindfulness during eating may be associated with noting satiety or being aware of hunger vs boredom as cues to eat. Yoga in general cultivates a mindful and non-judgmental attitude during yoga practice, and the effects of this may spill over into non-yoga class time, as detailed below. Mindful eating skills differ from cognitive weight management skills such as maintaining food diaries and counting calories. For instance, eating after feeling full and eating quickly are both factors associated with lower mindfulness. Yoga, walking, and other types of exercise were evaluated regarding mindful eating practices. Both the years of yoga practice and the number of minutes of yoga practice per week were associated with higher mindful eating scores. Other physical activity was not associated with mindful eating, with the exception of walking more than 200 minutes per week, which the investigators thought was a statistical chance finding. In addition, those with higher mindful eating scores had lower body mass indices. Mindful eating may be one mechanism by which yoga may improve weight.
The effects of yoga on body composition, cardiovascular endurance, and anaerobic fitness were evaluated in boys age 12 to 15.6 Participants were randomized to one-year yoga training, 45 minutes per day, for 3 days per week. Participants in the control group were sedentary. At the end of the intervention period, the yoga practitioners had significantly lower body fat percentages than the control group. Cardiovascular endurance, as measured by a step test, and anaerobic power, as measured by a jump test, were also significantly better in the yoga group compared to the control group. Obviously, the sedentary control group would not be expected to show improvement in fitness; however, given the sedentary nature of many people today, this study does show a difference that could be clinically relevant. An interesting demographic: Not many clinicians would likely access this population and recommend yoga, so the results are not highly generalizable.
Adolescents with obesity may be best treated with behavior modification approaches, teaching the children to adopt a healthy lifestyle. A randomized controlled trial enrolled obese adolescents and compared those randomized to a behavior modification program and those in the control group.7 The behavior modification program included 4-hour structured sessions that were held weekly for 16 weeks, and each session involved 2 hours of behavior modification or dietary instruction and 2 hours of yoga therapy. The participants also visited a dietician four times during the program. Eating behavior was measured via the Dutch Eating Behaviour Questionnaire, a validated scale that measures three components of eating behavior: emotional, external, and restrained eating. Emotional eating is eating in response to emotional states such as fear and anxiety. External eating is eating in response to external food cues such as the sight or smell of food, and restrained eating is overeating when the cognitive resolve to minimize food intake is abandoned. The experimental group lost significantly more weight than the control group, and they experienced improvements in emotional eating, external eating, and restrained eating significantly more than the controls. Yoga was one component of the intervention, and it is unknown how much each of the components contributed to the weight loss and eating behavior changes.
A smaller study in Hispanic youth also noted improvement in weight with Ashtanga yoga practice over a 12-week period.8 Average weight loss over the 12 weeks was 4.4 pounds, which was statistically significant from baseline. Four of the five children with low self-esteem at baseline improved. Two of the 14 subjects had decreases in self-esteem compared to baseline. The investigators postulate that these declines may be due to the humbling experience of yoga practice, where some of the children may have realized that they could not achieve certain poses or that they progressed slower than their peers. The investigators also note that with additional yoga practice, participants may be able to improve their poses while being more able to accept their limitations. Anxiety also improved in those with baseline anxiety. Limitations of this study include the single-group, lack of long-term follow up, and the small sample size.
The Vitamins and Lifestyle (VITAL) study was a large questionnaire-based study, and one analysis focused on yoga and weight change over midlife, ages 53 to 57.4 More than 15,000 participants were analyzed for weight and weight change, yoga and physical activity, and diet, using a linear regression analysis. Among both normal and overweight participants, lower weight gains were associated with increasing intensity of yoga practice, with larger associations for those who were overweight. For instance, for those who were overweight at age 45, there was an 18.5 pound lower weight gain for long-term yoga practitioners compared to non-practitioners. Food intake only explained 1.2 pounds of this difference. The main limitations of this study are that it used self-administered questionnaires and self-reported weights, the data are retrospective, and it isn't immediately obvious that they controlled for confounding variables.
Physical activity is difficult in obese patients, and exercise programs must be tailored for them. A prospective single-group clinical study enrolled 47 obese participants in a 6-day residential treatment program including seated yoga and dietary changes.9 Compared to baseline measures, body mass index, lean body mass, waist and hip circumferences, total and HDL cholesterol, and leptin levels all decreased. Hand grip strength and balance increased. The investigators note that not all of the changes were beneficial, specifically the decreases in HDL and in lean body mass, and that these changes may be related to the drastic change in diet.
To find meaningful reductions in weight, longer term studies must be completed. In the shorter term, yoga is associated with reduced risk factors for cardiovascular disease and diabetes mellitus. In one study, 98 subjects enrolled in an outpatient 8-day lifestyle modification program based on yoga principles.10 The intervention included physical postures, breathing exercises, relaxation techniques, education, and group support. There was no control group, and a pre-post analysis evaluated differences from baseline to the end of the intervention. Subgroup analysis defined those with abnormal fasting glucose and cholesterol at baseline. In these higher-risk groups, fasting glucose, total and LDL cholesterol, and triglycerides were all significantly lower at the end of the intervention compared to baseline, and HDL cholesterol was significantly higher. Although this short-term study did not evaluate weight, it did show improvements in variables associated with obesity.
An important component of yoga is relaxation training. In some patients, inadequate coping with stressful events leads to overeating, and learning how to cope in other ways may be beneficial for these patients. Relaxation techniques can aid patients in changing their responses to stress, for example avoiding emotional eating.11 The effects of relaxation training were studied in 60 inpatient obese women who reportedly were emotional eaters.12 The patients were admitted for weight reduction treatment and rehabilitation. Participants were randomized to one of three groups: individual relaxation training sessions, virtual reality sessions, or control, who received only standard hospital-based care. Weight decreased in all three groups, likely due to the common treatment all inpatients received. Relaxation training reduced emotional eating episodes, depressive and anxiety symptoms, and improved perceived self-efficacy for eating control. The virtual reality condition decreased emotional eating more than the relaxation training. While the relaxation training sessions differed from yoga sessions, the findings may be applicable to relaxation training in general.
The long-term success of weight loss is fairly low, meaning most of the lost weight is regained within five years.13 Finding a "non-diet" approach that is consistent with a healthy lifestyle may be most beneficial for maintaining weight loss. Stress reduction training can lead to improvement in stress management behaviors and symptom discomfort; it can also lead to improved self-efficacy for low-fat eating.13 While one randomized study did not show a difference in weight loss between three different stress reduction interventions, benefits in behavior were noted.13 Changing behaviors to more beneficial behaviors may have long-term benefits. One randomized study comparing yoga to cognitive behavioral therapy found that both interventions equally reduced both psychological measurements, such as self-rated stress and quality of life, and physical measurements of stress such as urinary catecholamines and salivary cortisol.14
Breathing techniques, called pranayama, are also a standard part of yoga practice. Breathing techniques are not usually done alone, but one study evaluated a specific breathing exercise as a treatment for obesity.15 This breathing exercise is called "Senobi," and it includes stretching the arms above the head and arching the back, similar to a back extension with pranayama, as in yoga. The investigators note that this exercise "could activate or recover sympathetic nervous system activity that leads to the loss of body weight."15 Using heart-rate variability testing, the investigators found that overweight women had less sympathetic nerve activity compared to "healthy" women. After one minute of Senobi breathing, up-regulation of sympathetic nerve activity and increased urinary noradrenaline, estradiol, and growth hormone occurred. After one month of using the Senobi breathing method three times per day, obese women had a statistically significant loss of body fat, from 39% to 35.8%. No side effects were discussed. While most physicians aim to teach relaxation training to decrease sympathetic output, this study is noting that increasing sympathetic output will help weight loss. How this relates to chronic stress and obesity is unknown.
Yoga does not include a calorie-restricted diet, even though some studies suggest that it helps with weight loss. Because yoga is multidisciplinary, often including changes in behavior, stress levels, and diet, it is impossible to determine if one aspect of yoga is "the active agent." It is very difficult to study in rigorous controlled research. Yoga is a type of lifestyle exercise that most patients can safely practice, even as elders.
The components of Hatha yoga, including physical exercises, relaxation training, and breathing techniques, each potentially could improve weight management. Studying Hatha yoga is difficult to do, because masking subjects to treatment group and finding a valid, inactive placebo is difficult. Also, many different forms of yoga exist, such as Iyengar, Hatha, Ashtanga, and Kundalini, and it is possible that some are better than others for weight loss. More research is necessary to make firm conclusions about yoga's effects on weight loss. However, enough research is supportive of yoga's benefits on flexibility, strength, balance, and stress reduction that recommending yoga to our overweight patients seems reasonable.
In general, learning yoga under the care of a qualified yoga teacher is necessary,16 especially for those with medical conditions or those who are very deconditioned. Precautions for yoga include avoidance of fatigue and pain, and that physical postures (asanas) should be done at one's own pace. Postures can be modified or assisted as necessary.16 For the obese patient, we can recommend yoga provided that it is done under the care of a qualified teacher.
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