Paleo, low-fat, low-carb, low-calorie: Weight loss is big business. Americans spend billions of dollars on weight-loss products and services ever year. If you’ve ever tried to lose weight, you have likely wondered which of the popular weight-loss programs is most effective.

You may have even tried several programs, or you may be trying to decide which to try. Now there is an answer to the bewildering question, “Which works best?”

Americans spend billions of dollars on weight-loss products and services ever year.

Commercial diet programs recommend dietary and lifestyle changes that are very specific. Each claims their program is better than the others. Even though consumers may be confused, they are still likely to spend the money on a program anyway, hoping for results.

A team of Canadian and American researchers set out to find concrete answers. Their findings have just been published.

Comparing Diets — From Atkins to Weight Watchers

The goal was to compare all the rigorous trials of branded diets that had been done and to measure how well they helped people lose weight.

The team looked at the most popular diet programs — Atkins, Weight Watchers, Jenny Craig, LEARN, Nutrisystem, South Beach, Ornish, Volumetrics, Biggest Loser, and Rosemary Conley to see which were the most effective.

They reviewed 48 studies of these diets. Those studies monitored more than 7,200 overweight and obese adults whose median age was 46 years. The median weight was 207.5 pounds.

There is no need for a one-size-fits-¬all approach to dieting because many different diets appear to offer considerable weight-loss benefits.

They concluded that the best diet for weight loss is — drum roll, please — the one you can stick with.

There were some minor differences among the diets, but they were so small they were not seen as likely to be important to those trying to lose weight. For instance, after six months people following the Atkins diet lost about four pounds more than those following the Zone diet. Across all the diets studied, though, weight-loss differences were minimal.

What Did Make a Difference

People who followed a low-carbohydrate diet lost 19 pounds more than those who were not on a diet. Those on a low-fat diet lost 17 pounds more than those not on a diet. After 12 months, most of that difference was gone, and low-carb and low-fat diets ended up offering roughly the same weight loss.

What did make a difference was exercise and behavioral support. Exercising, being part of a weight-loss group, or receiving weight-loss counseling all increased weight loss by from five to seven pounds.

“Our findings should be reassuring to clinicians and the public that there is no need for a one-size-fits-all approach to dieting because many different diets appear to offer considerable weight loss benefits…[M]any patients have difficulties adhering to strict diets that may be particularly associated with cravings or be culturally challenging (such as low-carbohydrate diets),” the researchers write.

Exercising, being part of a weight-loss group, or receiving weight-loss counseling all increased weight loss by from five to seven pounds.

The best bet is to choose the diet that you are most likely to stick with from among those that have proven weight loss results, say the researchers.

The findings are similar to those of the Joint Guidelines from the American Heart Association, the American College of Cardiology, and the Obesity Society. All concluded that all popular diets are about the same.

In other words, stick with what works for you and know that there is no magic pound-shedding plan. And though the researchers didn’t study this, switching between diets may offer more choices and variation as you search for diet and lifestyle changes you can live with.

One word of caution: the study did not look at whether the diets meet nutritional recommendations for good health. Certainly, weight loss is beneficial for many medical conditions, but the quality of a person’s diet is also important to long-term health.

The study is published in the Journal of the American Medical Association.