(CBS News) – What’s the best diet for your weight loss investment? According to Consumer Reports, it’s Jenny Craig.

The weight loss plan received a first place ranking in a listing by the magazine.

So, does that make Jenny Craig the best plan for you? According to CBS News Medical Correspondent Dr. Jennifer Ashton — not necessarily.

Ashton and Nancy Metcalf, senior program editor for Consumer Reports, discussed the diet plan rankings and what they mean for you if you’re ramping up to lose weight.

Metcalf explained that the rankings were based on clinical studies of the diets. “We crunched the numbers on how much weight people lost in the short term, six months, in the long term, a year. How many people stayed on the diet. And then we also analyzed the nutritional content of the diet and gauged how well it went with the federal guidelines and crunched all those numbers together to get the big rating,” she said.

The study that Consumer Reports based their results on, by the Journal of the American Medical Association, was funded by Jenny Craig. But Metcalf claims, “Some new studies came out last year of Jenny Craig, which had great results. After a year, the average participant had taken off eight percent of their weight, which doesn’t sound like a lot, but actually is kind of a home run for a big diet study. … And they kept it off for a year.”

Slim Fast earned the No. 2 spot.

For some Slim Fast is looked at as a ‘quick fix’ and not long-term sustainable. Metcalf said, “It kind of is. They get good results six months level. But what you see after a year is people just drop out. Because I think maybe they get tired of eating the same stuff all the time.”

Weight Watchers took the third place spot and the Zone plan came in fourth.

Consumer Reports diet plans ranking:

1. Jenny Craig
2. Slim Fast
3. Weight Watchers
4. Zone

But how do you pick the best diet plan for you? Dr. Jennifer Ashton said “a couple of medical caveats apply.”

“No. 1 – is it safe?” she explained. “A lot of diets can affect weight loss in the short-term, but they might be dangerous to your health. In terms of caloric intake; you don’t want to go below 1,200 calories a day if you’re a woman, 1,600 if you’re a man.”

She continued, “If you’re picking the diet plans, ask yourself a couple of questions. Who’s managing it, nutritionists, dietitians, physicians; are there social workers involved? And what, exactly, are they promising you for what amount of money? Because we have to remember, one of the goals of the commercial diets is weight loss. The other one is making money. You want to do your due diligence.”

It was noted that the Atkins Diet didn’t even make the top four. As to the success rate of the low-carb craze Dr. Ashton said, “The low-carb controversy continues – continues to be a controversy. There’s some important medical and nutritional dietary facts you need to know about that. Not every carbohydrate is equal and not every carb is evil.”

But whatever plan you choose, Ashton said the immediate benefits to weight loss are huge. “Even about five percent of weight loss can pay off to a huge health benefit,” she said. “The key long-term, it has to be sustainable. It has to work for you.”