Dr. Max Gomez: Research Finds Jenny Craig, Weight Watchers Can Help Keep The Lbs. Off

NEW YORK(CBSNewYork) -- Warm weather has arrived and people's thoughts have turned to losing weight for bathing suit season.

Higher temperatures also lead to an age-old question; what's the best way to slim down for summer?

As CBS2's Dr. Max Gomez explained, a new study shed light on the most effective diet plans.

Almost all plans claim to help you lose weight, and most do, for a while. But which ones are backed by science and can help keep the weight off for the long-term? It turns out there are really only two.

Yoga was not always easy for Nari Koroghlian. Two-years-ago the 43-year-old was recovering from Hodgkin's lymphoma and was overweight. Today, she is 22 lbs lighter.

"My lifestyle really started to change because of Weight Watchers," she said.

A review of the 11 most popular commercial diet programs compared weight loss, adherence, and harm among obese patients. It found that Weight Watchers and Jenny Craig are the most effective for helping people lose weight and keep it off.

"On average, Weight Watchers participants lost at least 8-lbs at the 12 month mark. Participants on Jenny Craig, on average, lost at least 15-lbs at the 12 month mark," Dr. Kimberly Gudzune, Johns Hopkins University School of Medicine, said.

Researchers noted that while many programs showed promise for short-term results they were limited and lacking evidence of long-term weight loss.

While average weight loss was modest, the health benefits are significant.

"For some people a commercial program may be the right answer for them. I think they are available to a large number of patients in the U.S. So I think it has to be something physicians consider as part of their arsenal or their tool box in thinking about weight management. However, they're not necessarily the right answer for all patients," Dr. Gudzune explained.

The U.S. Preventative Services Task Force recommends obesity screening and counseling and some health plans may cover the cost of commercial weight-loss programs for overweight patients.

Koroghlian loves the smartphone app that tracks her food and activity and said she regularly attends meetings.

"I interact. I get support. I can raise my hand and talk about things, get advice," she said.

Koroghlian is now a yoga instructor. Weight Watchers magazine featured her story.

It's not that other diet plans aren't necessarily effective, but that they haven't done the rigorous studies needed to prove that they work.

Researchers said Nutrisystem has been shown to work, but there aren't good, long-term studies to prove that the weight stays off.