These results suggest that it's not necessary for people
to cut back carbohydrates to lose weight, according to
Dr. Arne Astrup of the Royal Veterinary and Agricultural
University in Copenhagen, who wrote an accompanying editorial.
Protein appears to encourage people to eat fewer calories
overall, Astrup noted, so if people simply increase their
intake of protein, that should help them lose weight.
"You can just eat a little more lean meat and low-fat
dairy products," Astrup recommended.
Lead study author Dr. David S. Weigle of the University
of Washington School of Medicine in Seattle and his colleagues
note that low-calorie diets rarely work. This has encouraged
researchers to consider that changing the ingredients
of the diet, but not its calories, makes a difference
in people's waistlines.
Previous research shows that low-carbohydrate diets,
typically high in fat and protein - are effective, the
authors report, but so are low-fat diets.
Weigle and his team speculated that low-carb diets may
work because they encourage people to eat more protein,
which decreases people's appetites and causes them to
consume fewer calories.
To investigate, the researchers followed 19 people placed
on different diets. As part of the first diet, which was
designed to maintain body weight and lasted 2 weeks, people
received 15 percent of calories from protein, 35 percent
from fat, and 50 percent from carbohydrates.
In the next diet, people followed a calorie-controlled
diet for 2 weeks, in which they got 30 percent of calories
from protein, 20 percent from fat, and 50 percent from
carbohydrates. People then spent another 12 weeks consuming
the same percentage of calories from each type of food,
but were told they could eat as many calories as they
wanted.
People reported feeling less hungry on the calorie-controlled,
high-protein diet. When they continued the diet but could
eat consume as many calories as they wanted, they took
in nearly 450 fewer calories per day and lost almost 5
kilograms (11 pounds).
Astrup explained that protein helps people lose weight
because, "calorie for calorie," protein makes people feel
fuller than carbohydrates or fat. The researcher noted
that it's unclear why protein works better at curbing
appetite.
SOURCE: American Journal of Clinical Nutrition, July
2005.
