Dieters who followed low-carb or low-fat plans for two years along with a lifestyle modification program lost the same amount of weight -- on average about 7% of their body weight or 15 pounds.
But throughout the two-year study, low-carbohydrate dieters had significantly increased HDL, or "good," cholesterol levels compared to low-fat dieters.
Heart Risk Factors Improved
During the first six months of the study, the low-fat dieters had greater reductions in LDL, or "bad," cholesterol, but the differences did not persist over time.
The study is not the first to suggest that low-carb weight loss programs like the Atkins diet are safe and may be slightly better than low-fat diets for reducing risk factors for heart disease.
But it is one of the longest to show this, says lead researcher Gary D. Foster, PhD, of Temple University’s Center for Obesity Research and Education.
Roughly three-fifths (58%) of the low-carb dieters and two-thirds (68%) of the low-fat dieters stayed on the respective diets for two years.
The study appears in the September issue of the journal Annals of Internal Medicine.
“For many years there have been concerns that the low-carbohydrate approach to weight loss was bad for the heart,” he says. “This study would suggest those concerns are largely unfounded.”
Low-Carb Diet Heart-Healthy
A total of 307 obese people took part in the research, with half following a low-carb diet and half following a low-fat diet.
The low-carb group was instructed to restrict carbohydrates to no more than 20 grams a day for three months, increasing their carb intake by about 5 grams a week after that as long as they continued to lose weight.
As with the Atkins plan, these dieters ate mostly protein from meat sources during the induction phase along with about three cups of green leafy vegetables, Foster says.
The low-fat dieters were told to restrict total calories to between 1,200 and 1,800 a day, with no more than 30% of those calories coming from fat.
All the participants attended group sessions designed to motivate them to stay on the diets. The groups met weekly at first and then monthly toward the end of the study.
“The No. 1 thing was getting people to keep track of what they ate and their activities on a daily basis,” Foster says.
Other topics included limiting eating to specific places and times, managing the holidays, and getting back on track after overeating.
Even though HDL profiles were better in the low-carb group, Foster says dieters who successfully lost weight on both diets showed improvements in heart disease risk.
He says people who want to shed pounds should pick a diet that is most likely to work for them.
“I think the main message is that people need to spend less time worrying about whether they should follow a weight loss diet that is low in this or high in that and spend more time learning strategies to help them stick to the diet they chose.”
Expert: ‘Extreme Diets Don’t Work’
Weight loss researcher Frank M. Sacks, MD, of Harvard School of Health says the more extreme the diet, the less likely someone is to stick to it.
“Extremely low-carbohydrate diets may be safe, but people tend to get sick of them after a few months,” he says. “In this study, 42% of the low-carbohydrate dieters dropped out over time. They also reported more symptoms associated with the diet.”
He agrees that dieters should choose a weight loss plan they can stick to, with the goal being safe, gradual weight loss.
By following his own advice, Sacks was able to lose 15 pounds over nine months and keep it off.
“Half a pound a week may not sound like much, but over the course of a year that’s 24 pounds, which is huge,” he says.