Cutting kilojoules, whether by trimming fat or carbohydrates, aids weight loss, but the low-carb approach may do a better job of reducing risk factors for heart disease, a new study suggests.
The findings, from a study of 200 overweight adults followed for one year, bolster evidence that moderately low-carb diets may be more effective at cutting certain risk factors for heart disease – like high levels of fats in the blood known as triglycerides, and a large waistline.
Still, researchers say that the real key to success is picking a lower-kilojoule diet you can live with for the long haul.
The study, published in the journal Cardiovascular Diabetology, looked at a weight-loss programme that was offered "telemedically" – with participants getting telephone advice from a nutritionist and sending in their weekly weigh-in numbers via cell phone.
All of the dieters were told to cut at least 500 calories (2100kJ) from their usual daily intake. Half did so by slashing carbohydrates – aiming to get less than 40% of their kilojoules from carbs, 35% from fat and 25% from protein.
The other half cut down on fat, with a goal of getting at least 55% of their daily kilojoules from carbohydrates, less than 30% from fat and 15% from protein.
The researchers, led by Sabine Frisch of Ruhr University of Bocham in Germany, looked at the patients' progress six and 12 months after starting the programme.
Both groups lost weight
Overall, they found, both groups lost weight – with the average weight loss at 12 months being about 13 pounds (5.9kg) in the low-carb group and 9.5 pounds (4.3kg) in the low-fat group.
When it came to heart risk factors, the low-carb group showed a greater average reduction in blood pressure and waist size one year out. They also had bigger improvements in triglycerides and HDL cholesterol at six months, though those advantages waned by the one- year mark.
But while the low-carb diet edged out the low-fat one, some dieters in both groups started regaining some of the pounds they initially lost. After the six-month mark, the average gain was around 4 pounds (1.8kg) in both groups.
That, Frisch and her colleagues write, underscores the primary importance of long-term dietary change.
"Compliance with a weight-loss programme," they write, "appears to be even a more important factor for success in prevention and treatment of obesity than the composition of the diet."
(Reuters Health, September 2009)