People who take part in a commercial weight-loss programme may indeed lose some weight - especially if they substantially cut kilojoules, a new study from Sweden finds.
Worldwide, around 1.5 billion adults are overweight and another half billion are obese. In the US, two-thirds of adults are overweight or obese. That's a huge market for commercial weight-loss programmes, but few studies have looked at whether they really work.
The popular Weight Watchers and Jenny Craig programmes are among the few that have been tested in clinical trials, with promising results: People in the programmes lost more weight over two years than people assigned to "usual care" - generally advice from a doctor or dietician.
How the study was done
The newest study followed over 9 000 adults who enrolled themselves in Itrim, a popular chain of weight-loss and exercise centres in Sweden. The company just recently expanded to the US, opening a centre in San Francisco.
Over a year, program clients lost an average of 11 to 25 pounds, depending on how strict they were willing to be with kilojoules.
On the other hand, up to one-quarter dropped out, according to a report in the American Journal of Clinical Nutrition.
The Itrim programme is different from its better-known competitors, according to Erik Hemmingsson, a researcher at the Karolinska Institute in Stockholm who led the study.
Strictest diet worked best
Weight Watchers promotes eating "normal food" and trimming kilojoules, while Jenny Craig typically provides pre-packaged lower-calorie meals, and then has people gradually go back to regular meals.
People in the Itrim programme choose an eating plan, with the help of a "health coach," and take up an exercise regimen. The strictest diet plan involves consuming liquid meals of just 2100kJ a day for six to 10 weeks, then gradually reintroducing normal food.
If that sounds too daunting, people can combine liquid meals and lower-kilojoule regular meals for a total of 5040kJ to 6300kJ per day, or stick with normal food but trim kilojoules to 6300kJ to 7560kJ per day.
What the study found
In their study, Hemmingsson and his colleagues found that the strictest diet worked best. Among nearly 3 800 clients who chose it, the average weight loss over one year was 25 pounds.
Almost 4 600 people who opted for the liquid meal/real food combo came in second. They shed 15 pounds, on average. Meanwhile, the group that stuck with normal food - 676 clients in all - trimmed an average of 11 pounds.
It remains to be seen how widely appealing the program could become, according to Hemmingsson, who was once employed by Itrim and has received consultancy fees from the company. (Itrim also funded the current study.)
This study was not a randomised trial. Everyone in the study chose to enrol, put their own money up and was motivated to shed pounds. Even so, clients dropped out: anywhere from 18% to 26%, depending on the plan. (The strict liquid-meal plan had the lowest dropout rate.)
And of course, they paid a price. But the findings do underscore the importance of old-fashioned calorie-cutting, Hemmingsson said.
"Kilojoules are still what counts and makes a difference regardless of the setting - clinical or commercial," Hemmingsson said.
Yet that simple principle - burn more kilojoules than you take in - is often forgotten when people try to shed weight, he noted. "It's not rocket science, but it works," Hemmingsson said.
Commercial diet programmes might help when people have trouble making those changes themselves, or staying motivated over time, according to Hemmingsson.
He said he thinks the support in the Itrim program is "absolutely crucial".
When people enter the program, they discuss their diet strategy with a health coach. And after the first three months - the "weight loss phase" - they start going to their local Itrim centre for a workout two or three times a week. They also continue to get diet and lifestyle advice.
Researchers still have a lot to learn about commercial weight loss programmes, including whether people maintain their initial success over the long haul.
"We generally need to raise the bar by designing studies with a much longer follow-up, say three to five years," Hemmingsson said.
(Reuters Health, October 2012)
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