Amgen is a decently valued stock that has an excellent business and also gives investors a way to potentially gain exposure to a lucrative weight loss market.If you want to invest in the fast-growing weight loss industry, going with stocks such as Eli Lilly or Novo Nordisk can seem like a great idea. They have leading weight loss products and possess some promising long-term growth opportunities. But they are already among the most valuable healthcare stocks in the world (their valuations are in excess of $ ...