India, Oct. 9 -- Every few weeks, a new fitness challenge starts trending on social media - from the 75 Hard challenge to the 21-day concoction challenge, and many more. These defined-day programs are the latest fitness buzz, with celebrities like Neha Dhupia, Alaya F, and Kapil Sharma giving them their stamp of approval. Promising quick results through meal planning, light exercises, and dietary changes, they are gaining massive popularity. But before you jump in, it's worth asking: what are the real health benefits, what are the risks, and what should you be eating while doing them? We ask experts to break it all down....