Oct. 14, 2003 -- Could it be true? Can you actually cut back on
Oct. 14, 2003 -- Could it be true? Can you actually cut back on carbs, eat more calories, and still lose weight? It may be so, say researchers.
Reported success behind low-carb diets is thought to be because you eat fewer calories. But this new study suggests that something more may be happening.
"It was a very happy study because everyone lost weight," reports Penelope Greene, PhD, a researcher with the Harvard School of Public Health. She presented her findings at the conference for the American Association for the Study of Obesity in Fort Lauderdale, Fla. this week.
In fact, her volunteers liked the food so much, they voted to continue the study, she tells WebMD.
Who wouldn't? The small group was catered to, literally, by an upscale Italian restaurant in Cambridge.
"The food had to be good, or people wouldn't eat it," Greene says. "Some salad ingredients were organic, chickens were free-range. That was the quality of restaurant we used."
As for the 21 volunteers: "All were over 50, overweight, and overly concerned about their future health problems if they didn't lose the weight," says Greene. "They were very motivated."
From the Kitchen ...
The chefs, she says, were fastidious in their preparation of these weight-loss diets. Under her tutelage, they got special training, special recipes, even specific, brand names to follow in preparing 12 weeks' worth of either low-fat or low-carb meals, she reports.
From the kitchens emerged quiches, puddings, halibut with Dijon sauce, poached salmon, chicken teriyaki, beef stroganoff, lots of vegetables, lovely salads, and foods made with only unsaturated oils -- all carefully prepared, all weighed to the gram and ready for pick up, every single day.
"There was very little red meat," Greene explains. In addition to teasing out the perfect weight-loss diet, "we wanted to show an effect on cholesterol, too."
Researchers randomly assigned two groups of volunteers to eat either low-fat or low-carb meals -- with women consuming up to 1500 calories a day and men maxing out at 1800 calories a day.
The low-fat weight-loss diet was outlined as 55% carbs, 15% protein, and 30% fat. The low-carb diet was 5% carbs, 30% protein, and 65% fat.
A third group also ate low-carb -- but this group got to eat an extra 300 calories, boosting their daily intake to 1800 calories per day.
"The extra-calorie group got the exact same recipes as the low-carb group," Greene explains. "But in the extra-calorie group, every item was increased by a few grams. The quiche, the crackers -- everything weighed a few grams more."
As for the low-fat changes: "If one group had chocolate pudding, so did the other. But one may have been made with skim milk whereas the other had cream. One quiche had cheddar cheese and bacon bits, whereas another had low-fat cheese and broccoli."
And 12 weeks later ... participants lost beaucoup weight:
- The low-carb, low-cal group lost 23 pounds.
- The low-fat group lost 17 pounds.
- The group getting 300 extra calories of low-carb food lost 20 pounds.
In fact, both low-carb groups lost more inches from their weight-loss diet -- four inches at the waist, and three at the hips, compared with the low-fat group, which lost three waist and two hip inches.
What's Happening?
"We really don't know," says Greene. "We know that it takes the body twice as much energy to process protein as it does fat or carbs. And low-carb diets tend to be higher in fat and protein."
However, she doubts that extra protein is enough to make the difference.
Perhaps more food is excreted, Greene tells WebMD. "This is all hypothesis. But it's possible that the body doesn't absorb it. These are questions that need to be answered."
Greene's results "do not surprise me," says Cindy Moore, MS, RD, director of the nutrition therapy department at The Cleveland Clinic, and a spokeswoman for the American Dietetic Association.
"For a number of years, we have been advising extremely obese individuals to eat a low-carb, high-protein, low-fat [weight loss] diet, and have had quite a bit of success," Moore tells WebMD. "I'm delighted that we are getting more specific science-based information comparing these diets."
It's interesting that the low-carb people lost more inches -- even with the higher calorie intake, says Moore. "What that begs is, we need to better understand what's happening."
For a long time, dietitians assumed that eating fewer calories was the perfect weight-loss diet, she says. "But it might be that something else is happening."
However, it's important to look at the long-term implications of staying on a low-carb diet, both researchers point out. Lack of certain vitamins and fiber could, in the long term, cause serious health problems (participants in this study took multivitamin/mineral supplements). But as a short-term solution, a low-carb weight-loss diet indeed looks promising.
