Metabolic Benefits of Controlled-Carb Nutrition

Earlier today (see blog entry below) I wrote about a study which found that losing weight may pose a risk in the long-term. While the study was limited in its ability to determine causation, it does pose questions - most notably 'does the type of diet used to lose weight affect health in the long-term?'

I included the importance of nutrient-density in the equation of risk-benefit and now another study published in the American Journal of Clinical Nutrition (2005 81: 1253-1254), suggests that a controlled-carb approach offers:

• A metabolic advantage
• A nutritional advantage
• A greater improvement in levels of triglycerides

An energy-restricted, high-protein, low-fat diet provides nutritional and metabolic benefits that are equal to and sometimes greater than those observed with a high-carbohydrate diet,” concluded the researchers.

For this study, researchers randomly assigned 100 overweight or obese women aged 40 to 58 years, with a body mass index of between 28 and 38, to one of two isocaloric 5600kJ diets for a 12-week period. Participants - 100 middle-aged, moderately obese women - were placed on a 12 week of diet with either of two isocaloric, restricted diets, each with similar fat content (20% of calories) but varied protein and carbohydrate content. The high-protein (HP) diet contained 34% of calories as protein with 46% of calories from carbohydrate, and the high-carbohydrate (HC) diet contained 16% of calories from protein with 64% of calories from carbohydrate.

• Both groups had similar weight-loss ~ about 16-pounds
• When the results were further evaluated according to initial serum triacylglycerol concentrations, patients with high triacylglycerol who consumed the HP diet lost 25% more weight and had greater reductions in body fat mass and serum triacylglycerol concentrations than did those with high triacylglycerol who consumed the HC diet
• Serum vitamin B-12 levels increased 9 percent with the high-protein diet and decreased 13 percent with the high-carbohydrate diet
• Folate and vitamin B-6 levels increased with both diets
• Both groups also experienced a decrease in LDL-cholesterol, HDL-cholesterol, glucose, insulin, free fatty acid, and C-reactive protein concentrations with weight loss

The authors conclude that HP diets are of particular benefit in patients with high circulating triacylglycerol concentrations.