If you wanted to get rich beyond your wildest dreams, there’s one way that’s guaranteed to let you fill the Grand Canyon with cash:

Invent a diet drug that takes off pounds, has no side effects and still lets people eat whatever they want.

Such a drug, of course, remains firmly in the realm of mythology, not pharmacology — and yet, because the payoff would be huge, the incentive to keep trying won’t go away.

Thus we read recently that a trio of new diet drugs is hitting the market, with the first one getting a public review from the U.S. Food and Drug Administration this week.

While researchers admit that none of the drugs is a “breakthrough” in providing a miracle cure for obesity, “even a modestly effective drug has blockbuster potential” for investors.

That’s because the U.S. obesity rate has surpassed a third of the adult population, and Americans appear uneasy about this trend and yet are unprepared to take the difficult steps necessary to resolve it.

Sadly, any ultimate resolution falls more on the shoulders of the individuals involved than it does on the larger society. Doctors can hector us, insurance companies raise our premiums and the government take action around the margins to inform us about healthier eating habits.

But, while schools can provide healthy foods and restrict unhealthy ones to their captive students, any government move that restricted the dietary options available to adult Americans in a way that was sufficient to have a real impact would be seen — correctly — as “nanny state” interference with our freedoms.

Lacking a “magic pill,” then, Americans have to see that what they need is their own “magic will,” by using their own willpower to, gasp, eat less and exercise more.

So, you say, if that’s the bad news, what’s the good news?

Sorry, but that is the good news. These new drugs may help a bit more than older ones, but meaningful weight loss still depends on using the organ between our ears to regulate what passes between our lips.