It doesn’t matter what kind of diet you use as long as you stick with it and combine it with exercise, according to a new study based out of McMaster University in Hamilton.

Popular diets like the Atkins Diet, Weight Watchers and Jenny Craig aren't much different when it comes to losing weight, according to the research, published Wednesday in the Journal of the American Medical Association.

What is important are the support systems the programs offer and combining them with exercise, said Bradley Johnston, the study’s lead author and an assistant professor of clinical epidemiology at McMaster's medical school.

"The debate about what diet is still best continues," Johnston said. "But we’ve shown they’re relatively the same."

For their analysis, researchers combined data from 48 randomized clinical trials that examined popular branded diets. In all, those trials involved more than 7,200 adults who were overweight or obese. Their average age was 46.

The research team looked at how much weight they had lost six months into their program and then again a year in.

After six months, there were small differences in the effectiveness of dietary regimes: People following a low-carb diet lost 19 more pounds than people who weren’t dieting, while people following a diet that was low in fat lost 17 pounds over and above those who weren’t dieting.

But at the one year mark, that difference was gone, and people had lost about the same amount of weight on either kind of weight loss plan.

'The differences between the different diets regarding their impact on weight loss were relatively small.' - Geoff Ball, associate professor and obesity expert in the Faculty of Medicine and Dentistry at the University of Alberta

"We wouldn’t recommend any specific kind of diet here," Johnston said. "Really, it’s about choosing one you feel you can best adhere to."

What’s critical to weight loss — no matter the diet — is including exercise and taking advantage of the "support systems" offered by the program, like meeting with dietitians, counselling and group support sessions.

As weight loss is a multimillion-dollar industry, a study looking at its overarching effectiveness was needed, said Geoff Ball, an associate professor and an obesity expert in the University of Alberta's faculty of medicine and dentistry.

"Given the popularity of these diets around the world, there has been a real lack of research to examine their relative benefits," Ball said. "But overall, the differences between the different diets regarding their impact on weight loss were relatively small."

While the study did look at factors like weight loss and body mass index, it doesn’t take into account the effects on a person’s cardiovascular system. Different diets could have different internal effects, Johnston said. "We do need to investigate further how it impacts your blood pressure and cholesterol.

"There may be important differences between those."

The Canadian Institutes of Health Research and the Public Health Agency of Canada provided funding for the study.