If there was a magic, one-size fits all diet that made everyone lose weight healthy, then all dieticians would agree on it. But it doesn't exist yet. However, dieticians do agree on many things: lower your fat intake, especially saturated fat; pick your carbs carefully; avoid fast-food and processed foods; etc. like Joe said.

But I think the other really important thing we can't forget here is TO CHECK WITH YOUR DOCTOR BEFORE STARTING A NEW DIET.

Here's a horror story to emphasize my point if the capital letters didn't do it. One of my neighbors, a fit man in his 50s, decided to go on the Keto diet with his wife and daughter. That's a no carb diet with major emphasis on proteins. Three months later, he was in the hospital for pancreatitis. Why? Turns out because of the drastic way that he cut carbs his body wasn't burning fat, but it was burning his muscle. When his muscles were burning, they released a bunch of triglycerides into his body and that caused his pancreas to inflame. He was in the hospital for three weeks, and he's still on a liquid diet.