The Scientific Rationale for the Efficacy of Yoga for Weight Loss and Maintenance

By: Sandeep (Anu) Kaur, MS, RDN, RYT-500 and Sat Bir Khalsa, Ph.D

Obesity has been on the rise for decades in the United States and is a critical risk factor associated with chronic diseases such as heart disease, hyperlipidemia, type II diabetes, hypertension, stroke, and certain types of cancer. Factors contributing to the obesity epidemic include a sedentary lifestyle with low levels of physical activity, a diet high in calories and low in nutrients, poor social norms around food choices, mindless and/or stress-induced overeating, and increased stress itself. In the United States, 36% of adults and 17% of youth are officially obese. Based on the Centers for Disease Control and Prevention guidelines, obesity is defined as a body mass index (BMI) of 30 or greater. Obesity prevalence is highest among middle-aged adults (40.2%) and older adults over the age of 60 (37.0%) compared to younger adults (32.3%). Despite recent studies showing a plateau in the growth in prevalence of obesity in certain geographic areas in the United States, the rates are likely slowing down rather than reversing. Adult and childhood obesity national percentages continue to remain above the government’s Healthy People 2020 program goal of 30.5% for adults and 14.5% for children.

Traditionally, weight loss strategies have focused mainly on diet and exercise as a method to decrease caloric intake and increase energy expenditure, which generally is effective with initial weight loss. However, most people regain weight over time due to regression in eating habits and decreased exercise adherence, underscoring the need for alternative forms of dietary and physical activity approaches that are effective over the long term. Other conventional treatments have included pharmacotherapy and bariatric surgery, which have potentially serious complications and do not directly address the underlying health behaviors or complex psychological issues associated with initial weight gain. Conventional psychotherapy and behavioral therapy have been used to manage disordered eating such as binge or stress eating and encourage positive behavioral changes and healthier food choices through cognitive restructuring and the adoption of more functional thought patterns. Mindfulness based therapies, such as yoga and meditation, promote self-regulation of attention on the present moment experience with an attitude of openness, acceptance and curiosity, and increase stress coping and resilience, which are both important characteristics for supporting change in health behaviors. Furthermore, movement based mindfulness strategies further add the physical dimension, improving fitness, respiratory function, and management of stress and physical tension.

To better understand how yoga affects weight loss, Ross and colleagues conducted semi-structured interviews with individuals who fit the national demographics, majority being white, educated females who were either overweight and had struggled to lose weight or who were of normal weight and had lost weight unintentionally through the practice of yoga. Of the practitioners, 95% reported positive psychological changes with a mindset focus on general health rather than exclusively weight loss, improved mood, emotional stability, reduced stress, increased self-esteem and self-acceptance. Mindfulness was a key component of the feedback received from the interviews. Participants reported increased mindfulness around the food they consumed and the connection to the emotions they felt. Yoga reduced unconscious and emotional eating, and participants also reported that the stress reduction associated with yoga shifted their attitude and allowed them to choose healthier foods. Another unique theme that emerged was emotional support. Sixty percent of participants indicated that the yoga community and culture at yoga studios played a role in feeling supported and yoga teachers served as role models, which was different from yoga in a gym setting. Additionally, 90% noted physical changes from increased muscle tone to improved sleep and decreased pain. Nearly half the participants reported losing weight specifically in their abdomen, which has special significance with respect to obesity and weight regulation.

Abdominal adiposity often noted with obesity has been shown to have a strong relationship with stress and cortisol release. Excessive visceral fat behaves as an endocrine organ, affecting levels of adipocytokines, such as leptin and adiponectin. Leptin is associated with increased inflammation and adiponectin which is protective, is low in the presence of obesity. Inflammatory cytokines, such as Interleukin-6 and tumor necrosis factor–alpha have also been shown to be released from adipose tissue leading to a state of low grade inflammation with the potential of becoming disease-related inflammation. The underlying mechanism for yoga’s effectiveness on stress-related eating has been hypothesized to involve the down-regulation of both the hypothalamic-pituitary adrenal (HPA) axis and the sympathetic–adrenal medullary response of the autonomic nervous system to stress. It is speculated that abdominal weight loss may also be an indication of decreased HPA axis activation. Evidence supports the finding that stress and the release of cortisol are associated with increased consumption of high fat, high sugar foods.

Physical activity is a critical component to keep obesity and chronic disease at bay, yet low exercise adherence is a common cause of weight gain. Bryan and colleagues assessed yoga’s impact on exercise adherence in inactive adult participants in a 10-week randomized controlled pilot study that had subjects meet twice-weekly for hatha yoga classes. Individuals in the yoga group went from an inconsistent exercise routine to consistently participating in the yoga class and doing additional exercise. Qualitative data from interviews with participants showed that they experienced increased self-awareness and improved perception towards their desire and their ability to exercise, which in turn increased overall exercise adherence. One participant shared, “yoga makes me feel better, and therefore I want more of it,” underscoring participants’ improved perceptions and mind-body awareness. Increase in general well-being, exercise adherence, and exercise self-efficacy (the belief in one’s ability to do the exercise) were all positively correlated.

In summary, yoga as a multi-dimensional mind-body activity offers more than just a form of energy expenditure through the physical postures and exercises. It likely plays a vital and stronger role in weight management through behavioral, physical and psychosocial effects which lead to improved healthy eating habits. More needs to be understood about yoga’s relationship with nutrition and biomarkers indicating dietary changes such as antioxidant intake. Current yoga studies are starting to look at the effectiveness of yoga programs on increasing dietary compliance, overall well-being and health behaviors in both normal weight and obese individuals. Yoga philosophy has always acknowledged the connection between mind and diet as one way to create harmony. Continued yoga research may offer insight and a better understanding of yoga’s role as a potential long-term, holistic approach to weight loss alone or in combination with conventional weight loss strategies.