The CSIRO Diet put to the test

The high-protein, low-carb approach to weight loss has been underpinned by new research from Australia showing that it can provide overweight women with greater nutritional and metabolic benefits than a high-carbohydrate diet.

For the study published in the American Journal of Clinical Nutrition, researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Adelaide 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.

The diets were in parallel design, but one was high-protein and the other high-carbohydrate.

The participants in both groups achieved the same weight loss success, of between 7.0 and 7.6 kg, and both also experienced a decrease in LDL-cholesterol, HDL-cholesterol, glucose, insulin, free fatty acid, and C-reactive protein concentrations with weight loss.

Folate and vitamin B-6 levels increased with both diets.

But the benefits of the high-protein diet were evident in participants with high serum triacylglycerol (a risk factor for atherosclerosis and coronary heart disease), who lost more fat mass on the high-protein diet than on the high-carbohydrate diet (5.7 to 7.1kg and 2.7 to 4.1kg respectively).

Triacylglycerol concentrations decreased more in both high- and normal- serum triacylglycerol patients with the high-protein diet than with the high-carbohydrate diet.

Serum vitamin B-12 levels also increased 9 percent with the high-protein diet and decreased 13 percent with the high-carbohydrate diet.

“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.

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Reference
Noakes M, Keogh JB, Foster PR, Clifton PM. (2005). Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women. American Journal of Clinical Nutrition, 81, 1298-1306