Yoga is beneficial for relaxation and flexibility but its use for weight loss is debatable.
Strength train for your bones, your metabolism and to maintain/ad muscle which will help you lose weight, do cardio to create a bigger calorie deficit and to keep/make your heart fit...eat a clean, healthy diet full of nutrient dense foods to repair and restore your body and get enough rest to allow your body time todo the work it needs to...
There is no ONE thing, all the pieces need to be in place.
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A man of sense is never discouraged by difficulties; he redoubles his industry and his diligence, he perseveres and infallibly prevails at last.
No, you need to eat right first off. Some cardio helps also. Yoga is good for its own reasons and can be done to aid in weight loss but I wouldn't count on it on its own.