a1 INRA, AgroParisTech, UMR914, Nutrition Physiology and Feeding Behavior, CRNH-IdF, 16 rue Claude Bernard, F-75005 Paris, France
a2 Armor Protéines, 35460 Saint Brice en Coglès, France
a3 SB Alliance – Direction de la Stratégie Produits, 78220 Viroflay, France
This study was designed to determine whether (1) protein type and (2) the dietary carbohydrate to lipid content affected daily energy intake, body weight and adiposity in rats receiving high-protein diets ad libitum over a 25 d period. Each of the ten groups (n 8) consumed ad libitum one of the diets described below. A normal protein diet (P14C56L30, containing whole milk protein) and nine high-protein diets were used. The composition of the high-protein diets varied in terms of two parameters: macronutrient composition and protein type. Three macronutrient compositions (P55C35L10, P55C15L30 and P55L45) combined with three protein types (Milk, Whey and βLac) allowed us to test nine diets. The results show that both protein type (βLac > Whey > Milk) and the carbohydrate to lipid ratio (P55L45>P55C35L10 or P55C15L30) modulated reductions in energy intake, body weight and adiposity in rats receiving high-protein diets ad libitum, when compared with rats fed a normal diet under the same conditions. By contrast, blood lipid profiles were mainly influenced by the carbohydrate to lipid ratio (P55C15L30>P55L45 or P55C35L10). Moreover, βLac protein was also the most efficient in tending to preserve lean body mass at the expense of fat mass, and improve blood metabolism hormones (insulin, leptin). Taken together, the present results show that whey-derived protein sources, and particularly β-lactoglobulin-enriched fraction, are of considerable value because of their ability to reduce both body weight gain and the adiposity index.
(Received April 12 2007)
(Revised July 23 2007)
(Accepted July 31 2007)
Abbreviations: AI, adiposity index; C/L ratio, carbohydrate to lipid ratio; HOMA-IR, Homeostasis Model Assessment of Insulin Resistance index; HP diet, high-protein diet; NP, normal protein diet; WAT, white adipose tissue