Rapid weight-loss regimen trumped gradual-loss approach.
"This study has shown that people who lose weight quickly are more likely to lose weight. It's the reverse of how we practice at the moment. The assumption that gradual weight loss is superior has no scientific basis," Katrina Purcell said while presenting a poster at the meeting.
Ms. Purcell credited two factors for the success of rapid weight loss over more gradual loss.
First, patient motivation: "They see better results. The first 2 weeks are hard--but once they see the results, they want to keep going and not stop. Patients on the gradual-loss diet get disheartened," said Ms. Purcell, a dietician at the University of Melbourne.
The second factor is ketogenesis triggered by the very low calorie diet used for faster weight loss.
"Part of the hypothesis was that ketogenesis would help rapid weight loss," said Dr. Joseph Proietto, professor of medicine at the University of Melbourne and coordinator of diabetes, obesity, and endocrinology research.
"We believe that part of the reason why people in the faster-loss group had a lower drop-out rate is that they were not really hungry," Dr. Proietto said.
When people lose weight, changes occur with several hormones, he explained. Ketones lead to release of cholecystokinin, a major satiety signal. When patients begin the rapid-loss diet, which is low in carbohydrates and fat, ketogenesis starts on day 2 and is in full effect by day 3 or 4.
In contrast, ketogenesis never occurs in the gradual-loss group. "Those patients do well for a few weeks; but by about the fifth week, their weight loss starts to level off," Dr. Proietto noted.
The study enrolled 120 people who were obese but otherwise healthy. Their average age was 51 years, nearly three-quarters were women, their average baseline body mass index was 35 kg/[m.sup.2], and their average baseline weight was 97 kg.
The 60 patients randomized to the rapid-loss group received a diet that consisted entirely of commercially available, liquid food-replacement meals, with their total daily calorie intake titrated to produce a 1.5-kg loss each week. Patients randomized to the gradual-loss group received regular food and liquid meal replacements at a total energy level designed to produce a loss of 0.5 kg/week.
The rapid-loss regimen ran for 3 months, while the gradual-loss regimen ran for 9 months. Patients saw a dietician every 2 weeks during the study. The researchers designed both regimens to achieve a 15% loss of baseline weight if completed successfully.
At the end of the regimens, 50 (83%) of the rapid-loss patients and 29 (48%) of the gradual-loss patients achieved a loss of at least 15% of their starting weight, the study's primary end point, a statistically significant difference.
For the entire study group, weight loss averaged 14% of starting weight in the rapid-loss arm and 9% of starting weight in the gradual-loss group, a statistically significant difference.
In the rapid-loss group, 59 of the 60 patients (98%) remained on their diet through the entire 3-month period, compared with 51 (85%) who stuck with the gradual-loss diet through 9 months, a statistically significant difference.
The fast-loss diet used in the study, which put patients on an average of about 900 calories per day, gave patients all necessary nutrients, stressed Ms. Purcell.
During 3 months on the diet, the 60 participants had no adverse events, no cardiac problems, and no loss of muscle mass, she added.
A successful method for weight loss begs the question of how well patients will keep their weight reduced, the researchers acknowledged.
The current study will follow patients for 3 years. In general, however, "once a patient loses weight, they are at the mercy of their hormone changes. We have a method [rapid loss] where patients can lose as much weight as with surgery, but they need pharmacotherapy" to maintain their loss, Dr. Proietto said in an interview. He noted that while some effective and reasonably safe drugs are available, more options are needed.
"We need pharmacotherapy [for weight maintenance] that is safe, cheap, and can be used indefinitely," Dr. Proietto said.
"There is no evidence that a person's weight set point changes with time." Because of that, drug therapy is the only reliable way to prevent regain in a person who has lost a substantial amount of weight, he added.
RELATED ARTICLE: VITALS
Major Finding: Patients on a rapid weight-loss regimen designed to trim 1.5 kg/week had better adherence and greater weight loss than did patients on a gradual-loss regimen designed to produce a 0.5-kg/week loss. A 15% loss of baseline weight occurred in 83% of patients on the rapid-loss diet and 48% of patients on the gradual-loss diet, a statistically significant difference.
Data Source: Single-center, randomized trial with 120 obese patients who began with an average body mass index of 35 kg/[m.sup.2].
Disclosures: Nestle Australia provided free liquid food substitutes for the study. Ms. Purcell had no disclosures. Dr. Proietto has served on advisory boards for Nestle and Abbott.
RELATED ARTICLE: MY TAKE
Long-Term Outcomes Are Key
The authors of this study on weight loss conclude that since the participants who lost weight more rapidly were more successful than those who lost weight gradually, perhaps it's time to revise the long-held assumption that gradual weight loss is better.
I disagree with that conclusion.
Plenty of data suggest that faster weight loss is not better than gradual weight loss. That's not to say that rapid weight loss is worse, it's just not better.
Several studies show that if you lose 20% of your body weight on a very low-calorie diet (VLCD) over 6 months compared with 10% of your body weight on a gradual weight-loss plan during the same period, over the long term you end up in the same place. This is because people on a VLCD gained more weight back compared with those who modify their diets in a less extreme way.
The same is true for low-carb vs. low-fat diets. Several studies show low-carb diets produce greater weight loss than low-fat diets in the first 3-6 months, but at 1 year the overall percentage of weight loss is the same for both diets.
A caveat of Ms. Purcell's study is the lack of long-term outcomes. Plans are underway to follow the groups for 3 years and those data are critical for comparing the two strategies.
In addition, the study groups were not compared in a fair way. The success of patients on the 900-calorie rapid-loss regimen was measured at 3 months versus at 9 months in the gradual weight-loss group. It would have been better to compare the two groups at the end of the 9-month period.
GARY D. FOSTER, PH.D., is director of the Center for Obesity Research and Education and professor in the departments of medicine and public health at Temple University School of Medicine in Philadelphia. He reports having no conflicts of interest.
BY MITCHEL L. ZOLER
FROM THE INTERNATIONAL CONGRESS ON OBESITY
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|Author:||Zoler, Mitchel L.|
|Publication:||Internal Medicine News|
|Date:||Sep 1, 2010|
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