Hi Kateyoga,
Looking at the answers in this thread, it seems that people experienced weight loss through a combination of asana practice, spinal breathing, meditation, and samyama. Spiritual practices offer some physical activity, but they also possibly change the metabolism and the relationship with food and eating, as they provide an alternative way of managing the body, the emotions, and the mind. 
Hi all.
I used to weigh 78 kg(before starting AYP) and now i weigh 53 kg. I lost 25 kg in about 18 months and more importantly the loss is permanent. However, that is not the only thing i lost. I lost depression also. I believe the effects come from a combination of all the practices. Obesity is an issue, not only of the body but also of the mind. That is why yoga is an important contributor. We all have experienced that it works at all the levels. It is our nature to look for one particular practice that can heal our situation, and of course if that practice is postures, we want the name of specific postures that will work. But, i could only get rid of my problem with the combination of all the AYP practices including the asana routine with some simple exercises.
Hi apkallu,
As far as muscles are concerned, postures and light calisthenics are enough if you do not want big muscles. If you want a good physique with overall strength and agility, i recommend a book by Pavel tsatsouline, Kettlebell simple and sinister. There are other books also. You may study the works of Pavel, Paul wade and others. Avoid training with machines. Consider using simple tools like kettlebells and gymnastic rings to build functional strength and endurance.
It is great that you have started your Asana practice and experienced changes in your body and energy through yoga. However, it’s important to address your concerns about losing weight and losing muscle mass.
It is true that yoga can have an impact on body weight and metabolism, but everyone is different and may experience different results. Yoga, in combination with a balanced diet, can help maintain a healthy weight and promote fat burning. However, yoga itself is unlikely to significantly burn muscle.
If your goal is to increase muscle mass, there are a few things you can consider:
Adequate nutrition: Make sure you consume enough calories and nutrients to maintain and develop your muscles. Opt for protein-rich foods like lean meat, fish, legumes, nuts, and dairy products. Also, include complex carbohydrates and healthy fats in your diet to get the energy you need for workouts.
Strength training: In addition to practicing yoga, consider adding strength training exercises to your routine. This can include weight lifting, body weight exercises, Pilates, or any other form of exercise that helps you build and strengthen your muscles.
Variation in yoga practice: If your goal is to gain muscle mass, you can incorporate poses and sequences that specifically work on strength and muscle tone. Look into yoga classes that focus on power, dynamic Vinyasa, or even consider working with a yoga teacher to tailor your practice to your goals.
Remember that yoga is a holistic practice that involves mind, body and spirit. It’s not just about physical changes, but also about cultivating a deeper connection with yourself. Maintain a balanced attitude towards your practice and be kind to yourself at every stage of your journey. If you have additional concerns about your health or any physical changes, it is always advisable to consult a qualified health professional.
Our Iyengar teacher at times emphasizes the aerobics of the asanas, and at times the isometrics and skeletal-building of yoga. We’ll do a lot of deep lunge positions holding them up to a minute each. I think we used to hold them longer but then I started counting while in them. Sun Salute has many weigh-bearing positions, as do “simple” things, even Tadasana. That 90 minute sessions once or twice weekly) plus walking and cycling are helping me feel lean and limber, and to be able to lift and work more easily. I really didn’t lose any weight without managing my eating a little better. But Iyengar Yoga Asanas, with stable alignment in what are usually not easy postures, held for a significantly long time, certainly improves my strength. With repetitive Surya Namaste, my shoulders and upper body are certainly building.
Currently my physical goal is to get down from 205# to about 150. Four months ago I was 205, now I’m about 185#.