'Crash Dieting' Not Inferior to Gradual Weight Loss

 Marlene Busko

October 16, 2014

Contrary to common wisdom and guideline recommendations, gradual weight loss is not better than "crash dieting" for achieving a lasting slimmer body, according to a new randomized controlled trial comparing the two strategies.

The authors suggest that clinical advice for the management of obesity should be altered on the basis of their findings.

The researchers, based in Australia, randomized overweight and obese individuals to either a very low-calorie liquid-meal-replacement plan for 3 months or a low-calorie diet for 9 months.

Those who lost at least 12.5% of their initial body weight then went on to a maintenance diet; the trial's primary outcome was to see whether weight loss was maintained 3 years later, explain lead author dietician Katrina Purcell (University of Melbourne, Australia) and colleagues, who published their findings online October 15 in Lancet Diabetes & Endocrinology.

"We were surprised at how similar the rates of [weight] regain were [in the two study groups, but] the real surprise was that more participants (about 80%) achieved a 15% weight loss in the rapid-weight-loss arm compared with those in the gradual-weight-loss arm (about 50%)," senior author Dr Joseph Proietto (University of Melbourne and Austin Health) told Medscape Medical News.

"Our findings show 12.5% or more weight loss is more achievable if undertaken rapidly," the researchers write. Thus, "our data should guide committees that develop clinical guidelines for the management of obesity to change their advice," they urge.

In an accompanying comment, two experts say that very low-calorie diets are now much more sophisticated than when they were first introduced and may be entirely appropriate for certain patients — for example, those best motivated by rapid weight loss.

But there are still some caveats, they caution.

More Patients on "Crash Diet" Complete Whole Study

The widespread belief that gradual is superior to rapid when it comes to weight loss has been questioned recently, say Ms Purcell and colleagues. But so far, no randomized clinical trials have looked at weight regain after rapid vs slow weight loss.

They randomized 51 men and 153 women age 18 to 70 with a body mass index (BMI) of 30 to 45 to a rapid or gradual weight-loss program, aimed at a 15% weight loss. Throughout the study, participants were instructed to do at least 30 minutes of mild- to moderate-intensity exercise (eg, take a brisk walk) each day.

In phase 1 of the study, participants in the rapid-weight-loss arm consumed three liquid meal replacements (Optifast, Nestlé Nutrition) daily, for a total of 450 to 800 kcal a day, for 12 weeks, with the aim of losing 1.5 kg each week.

Meanwhile, participants in the gradual-weight-loss arm consumed one to two liquid meal replacements (Optifast) a day plus regular food — based on the Australian Guide to Healthy Eating recommendation (15% protein, 25% to 30% fat, and 55% to 60% carbohydrate) — for a 400- to 500-kcal/day deficit, for 36 weeks, with the aim of losing 0.5 kg per week.

All participants received free meal replacements, similar dietary advice, and saw the same dietician every 2 weeks.

A total of 50 patients (50%) in the gradual-weight-loss arm and 76 patients (81%) in the rapid-weight-loss arm achieved a 12.5% weight loss during the allotted time and were eligible to enter phase 2 of the study.

In phase 2, participants were instructed to follow an individualized weight-maintenance diet, based on the Australian Guide to Healthy Eating, and they met with the dietitian at weeks 4 and 12 and every 12 weeks thereafter for 144 weeks.

A total of 43 patients from the gradual-weight-loss group and 61 patients from the rapid-weight-loss group completed phase 2.

At the end of the study, completers who had been in the rapid- or gradual-weight-loss groups each had regained about 71% of the weight they had lost.

"Very low-calorie diets (about 800 kcal/day) achieve rapid weight loss, which possibly motivated the patient more than gradual weight loss, and in addition, the diet we used has a very low carbohydrate content, so the patients develop ketosis, which suppresses hunger," Dr. Proietto said.

"The disadvantages include that it is necessary to purchase a properly formulated very low-energy diet and some patients do not like the taste or the idea of replacing solid food with a liquid diet for two to three meals a day."

"Slow and Steady" Does Not Win the Race

Ms Purcell says: "Across the world, guidelines recommend gradual weight loss for the treatment of obesity, reflecting the widely held belief that fast weight loss is more quickly regained.

The myth that rapid weight loss is associated with rapid weight regain is no truer than Aesop's fable.

"However, our results show that achieving a weight-loss target of 12.5% is more likely and dropout is lower if losing weight is done quickly."

In an accompanying comment, Dr Corby Martin and Dr Kishore Gadde (Pennington Biomedical Research Center, Baton Rouge, Louisiana) agree.

The new study does suggest that in the case of weight loss, "slow and steady does not win the race. The myth that rapid weight loss is associated with rapid weight regain is no truer than Aesop's fable," they state.

"Very low-calorie diets are formulated better now to provide adequate protein and essential micronutrients than they were when first introduced decades ago and are regarded as safe when given under expert supervision."

These meal replacements are simple to use, and rapid weight loss can be motivating, they point out.

"Clinicians should bear in mind that different weight-loss approaches might be suitable for different patients in the management of clinical obesity and that efforts to curb the speed of initial weight loss might hinder their ultimate weight-loss success," they observe.

However, they caution, these diets are still associated with some risks — eg, fatigue, constipation, and gallstones — and are therefore "not appropriate for all patients."

The study was funded by a National Health and Medical Research Council project grant and the Sir Edward Dunlop Medical Research Foundation. Nestlé Healthcare Nutrition Australia supplied the Optifast but did not commercially sponsor the trial. Dr Proietto was chair of the Optifast medical advisory committee for Nestlé Healthcare Nutrition Australia from 2005 to 2010; the coauthors have reported no relevant financial relationships. Dr Martin has received research support or consulting fees from Eisai, Georgia State University, Jenny Craig, Orexigen, Elcelyx/NaZura, Mitchell Silberberg & Knupp, and Adventis Health System/Sunbelt. Dr Gadde has received research support from Amylin, Eisai, and Medical University of South Carolina and has previously owned stock in Orexigen.

Lancet Diabetes Endocrinol. 2014. Published online October 15, 2014. Article, Editorial

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