It supports previous evidence that a high-protein diet can reduce body weight and increase insulin sensitivity but suggests that the type of protein may also have a role to play.
If the findings are confirmed in people, they could have a significant impact on manufacturers involved in the weight loss market and those catering to Atkins fans.
Researchers from the University of Adelaide and the Commonwealth Scientific and Industrial Research Organization also based in Adelaide, Australia, fed rats a high-fat diet (300g fat per kg) for nine weeks, then switched to a diet containing either 80 or 320g protein per kg, provided by either whey protein concentrate or red meat for six weeks.
High dietary protein reduced energy intake and visceral, subcutaneous and carcass fat, they report in this month's issue of the Journal of Nutrition (134:1454-1458).
Increasing the dietary density of whey protein, but not of red meat, reduced body weight gain by 4 per cent, they add, while whey protein also reduced plasma insulin concentration by 40 per cent and increased insulin sensitivity, compared to meat protein.
These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity.
The development of new functional foods and drinks, particularly adult and sports nutrition products, has led to increased usage of whey protein concentrates and isolates, with 2002 consumption of all whey products at nearly 770,000 tonnes, acording to Zenith research.