Low-carb and high-carb diets work equally well for maintaining weight loss, Australian researchers report.

People had the same success in keeping off the weight they’d lost after sharply cutting their calorie intake for 3 months if they followed a low-carb (also called high-protein) diet or a high-carbohydrate regimen for the following year, Dr. Elizabeth A. Delbridge of the Heidelberg Repatriation Hospital in Victoria and her colleagues found.

Some studies have suggested that high protein diets may be a more effective way to lose weight short-term than high carbohydrate diets, Delbridge and her team note in their report. But there’s less evidence on which approach might be better for helping people to keep off weight they’ve lost, and whether the two diets have different effects on heart health.

To investigate, Delbridge and her team assigned 141 men and women who’d completed the weight-loss phase of the diet to a year on a diet in which 30 percent of their calories came from protein, or one consisting of 15 percent protein. Both groups also were instructed to keep their fat intake below 30 percent of total calories, and to focus on reducing saturated fat.

The study participants had lost 16.5 kilograms (36.4 pounds), on average, and only regained 2 kilograms, or about four pounds, over the following year.

While all the study participants saw their blood pressure go down as they lost weight, average blood pressure went up in the high-carbohydrate group during the weight maintenance phase, but the high-protein dieters were able to sustain their blood pressure reduction.

While people found it easy to stick to the high protein diet, Delbridge and her team say, the low-protein dieters “struggled to consume the recommended amount of carbohydrate (55%) and to limit their protein intake to 15%.”

But the low protein group still managed to keep their protein intake at about 22 percent of their calories, significantly below the 30 percent maintained by the high-protein dieters. And there was no significant difference between the two groups in the amount of weight they kept off.

The findings show, the researchers conclude, that “free-living overweight and obese people” (as opposed to those studied in an inpatient clinic, for example) were able to stick with recommended diet and keep off the weight they had lost for 12 months.

SOURCE: American Journal of Clinical Nutrition, November 2009.