What's whey more slimming than meat?

So if protein is great for slimming and toning, all I need to do is get more meat into my diet, right? Not quite. New research suggests some proteins are better than others at reducing body fat.

Scientists at the University of Adelaide and CSIRO looked at the response to a diet high in whey protein compared to a red meat diet in insulin-resistant rats. They tested for insulin sensitivity and body fat levels.

After 9 weeks on a high fat diet (300g fat per kg body weight), the rats were switched to a diet containing either 80g protein or 320g protein per kg for 6 weeks; one group were fed red meat, and the other whey protein concentrate (WPC). While both protein diets led to reduced body fat and less eating, rats on the whey diet had 4 percent greater weight loss, 40 percent lower insulin and greater insulin sensitivity compared to the red meat eaters.

"These findings support the conclusions that a high-protein diet reduces energy intake and adiposity [body fat] and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity," the research team noted.

Aussie Bodies Nutritionist Leigh Blashki said studies of this kind supported the argument that protein supplements such as WPC are not a just stand-by for eggs, meat and dairy, but are in many ways superior and should be regarded as an important part of an active person's healthy diet.

"Just as there are good fats and bad fats, and just as there are different kinds of carbs that impact blood sugar differently, there are also proteins with different ratings for useability and digestibility," Blashki said.

"Whey proteins and meat both rate the highest possible score for absorbability and useability, according to the PDCAAS scoring method. But WPC as found in formulations like Perfect Protein, has a number of functional 'fractions' that studies are now showing confer a number of health and weight management benefits."