High-protein diets containing different milk protein fractions differently influence energy intake and adiposity in the rat

Abstract

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 bLac) allowed us to test nine diets. The results show that both protein type (bLac . 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, bLac 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 b-lactoglobulin-enriched fraction, are of considerable value because of their ability to reduce both body weight gain and the adiposity index.Body composition: Energy intake: High-protein diet: Whey-protein fractionThe macronutrient composition of a diet is known to influence energy intake, energy metabolism and long-term changes to body weight and body composition. High-protein diets (HP diets) have been studied extensively for their ability to reduce total energy intake and body weight, and to limit lipid deposition 1 -5 . Of the dietary proteins, dairy proteins are widely employed as ingredients in order to increase the protein content in the formulation of high protein-containing foods. Dairy proteins comprise two major fractions, i.e. casein and whey protein, that represent 80 and 20 % of the total protein, respectively. Both caseins and whey proteins are considered to be high-quality proteins but they differ markedly with respect to their physicochemical properties, their amino acid composition, and their behaviour during digestion and absorption in the intestine 6 . These differences give rise to different patterns and kinetics of amino acid delivery to the blood, and are responsible for a variety of effects on protein metabolism following the ingestion of either casein or whey protein 4,7 . Whether these differences might also affect energy intake, energy metabolism and long-term changes to body weight and body composition in response to high-protein foods formulated with casein or whey protein, remains poorly documented. Moreover, not only the protein content but also the associated carbohydrate to lipid (C/L) ratio has bee...

A high-protein neonatal formula induces a temporary reduction of adiposity and changes later adipocyte physiology

“…The effectiveness of high-protein diets in reducing adiposity shown previously in adult humans (39,50) and animals (7,9,29,42) was clearly proved for suckling piglets in the current experiment. The present obtained data further strengthen our previous observations (37) by showing that the reduction in adiposity is not limited to perirenal adipose tissue.…”

Bioactivity in Whey Proteins Influencing Energy Balance

“…Veldhorst et al showed that a diet containing proteins, carbohydrates and fat providing 10, 55 and 35% energy, respectively, reduces hunger in humans if whey proteins were included in comparison to either soy and casein [10]. Similar results have been obtained from a study conducted in rats, which showed that whey protein concentrate with energy content of 55% reduced cumulative energy intake compared to whole milk protein if the former protein had been supplied in a diet with either 35% and 10% energy from carbohydrates and lipids, respectively, or in a diet with 45% energy solely from lipids [11]. No differences in cumulative energy intake were observed if the proteins were provided in diets with 15% and 30% energy from carbohydrates and fats, respectively.…”

“…Long-term glycomacropeptide intake has also been shown to improve fasting blood insulin levels in both humans [29] and rats [9]. Similarly a high protein diet (55% kcal) with β-lactoglobulin as it source of protein was shown by Pichon et al [11] to reduce insulin resistance and improve fasting blood insulin levels in rats to a greater extent than that of comparable high whey protein concentrate diet. The actions of α-lactalbumin and β-lactoglobulin on insulin sensitivity and glucose homeostasis may be due to the bioactive peptides in the proteins, since several dipeptides from α-lactalbumin and β-lactoglobulin have been found to increase glucose uptake in L6 myotubes and isolated skeletal muscles in vitro [39].…”

“…In addition to this whey protein, β-lactoglobulin has also been shown to influence energy intake. The study by Pichon et al that showed data highlighting the importance of dietary composition on whey protein effects on energy intake, also tested the effects of β-lactoglobulin on energy intake in rats and found that β-lactoglobulin reduced energy intake compared to whole milk proteins [11]. In summary, consumption of whey proteins as an isolate or concentrate appears to reduce food (energy) intake in humans and rodents by inducing satiety compared to casein, soy or carbohydrates.…”

“…In further support for a role for lactoferrin in reducing adiposity, it has been shown in vitro that this whey protein specifically inhibits adipogenesis and lipid accumulation in adipocytes [31,32]. Although Pilvi et al study showed that β-lactoglobulin was the least effective whey protein for inducing weight loss and for preventing weight gain [30], Pichon et al found that β-lactoglobulin (55% energy) causes the least weight gain when supplemented in a diet containing only fat providing 45% of energy in comparison to a diet containing 35% and 10% energy from carbohydrates and fat or in a diet with 15% and 30% energy from the same macronutrients, respectively [11]. The data again highlights the importance of macronutrient composition on whey proteins effects on energy balance.…”