Yes. It's a myth that yoga is all about stretches and flexibility. In reality, Yoga can be used as a very effective tool to build overall strength in the body.
Lifting your own body weight in yoga is just as effective as lifting weights. While doing yoga based strengthening postures, you have to support with your muscles and that helps in building strength from inside rather than just having pumped up muscles. By holding the positions longer, doing more repetitions, and learning new yoga poses, you can make your yoga practice more or less challenging, just as you can with traditional bodyweight exercises like squats and lunges. You can eventually move from basic postures for strengthening to advanced ones like arm balancing postures like Crow and handstand. Muscular development doesn't necessarily mean a healthy body. Health is a state where all the internal organs function properly which can be seen through practice of yoga.
Yoga can be a more balanced way to do strength training. It helps you move with ease - your daily activities like walking, sitting, lifting things etc. It makes you move your body in ways that was designed to move, helps you move from your joints , keeping the joints active and functioning properly. Also yoga moves the muscles in many directions with twisting and arching not just back and forth. Yoga tones muscles all over your body, in balance with each other. Weight training exercises typically isolate and flex one muscle or muscle group at a time.
In Yoga, muscle stretches as it contracts which gives the muscles a more elongated sleek look along with increasing the flexibility in joints and muscles.In weight training, however, it works in the opposite principle of concentric contraction where the muscle gets smaller as it contracts. Although they help in building muscle and give a compact bulging look, this can cause stiffness in the body without proper stretches and also lead to injury.
Muscle endurance increases with yoga as you hold the poses for long time and also sometimes repeat it a few times during a session.
If you are looking to have bulky pumped up muscle, weight training is for you. Here, exercising progressively is the key to gain the strength of musculoskeletal system. Traditional weight training approach is the best to have a sustained, injury free body. As your muscles adapt to the resistance with lesser weights and get stronger, you can add more weight so you don't overload your muscles and bones and get the desired results. As you add more weights , you continue to grow the size and strength of your muscles.
All said , I am not against weight training. The key here is to be more attentive and aware of your body, mind and breath. You can do a bit of strength training using weights along with yoga to be fit. Trying out different techniques will give you new challenges and test your body n different ways. Whether you train with weights or do yoga, if you move with self awareness and listen to your own body , you can come out feeling energised and fulfilled.
Different types of yoga poses build muscle tone in different ways. There are also beginners, intermediate and advanced postures to help in strengthening according to your level. However some Poses like Plank, Chaturanga, boat (navasana), Warrior(virabadhrasana), utkatasana, bhujangasana are very effective in strengthening over all body - core,arms, back and legs.
Strengthening postures in Yoga often comes with a challenge of balancing as well making the whole process calm and meditative and they also improve your flexibility to some extent. All work hand in hand.
There is no special diet pattern to follow. Although for overall health and wellbeing, it’s highly recommended that an individual understands her/his body metabolism and follows a balanced nutritious diet.