High protein diets have weight loss effects. The reason for this is not fully understood, but may relate to the ability of protein to increase satiety. Alternatively protein can delay gastric emptying and thus slow the transit of food through the gut, and this has beneficial glycaemic effects. The weight loss effects of protein argue against a simple energy balance model of weight gain, because replacing carbohydrates in the diet with an equal amount of protein causes beneficial weight loss effects. If the energy balance equation theory of weight gain were true, this would not be possible. The reason that protein can cause weight loss without a need to reduce calorie intake may relate to the efficiency with with protein is utilised as an energy substrate in the body, with amino acid delivering a net lower amount of energy than an equivalent amount of carbohydrates. This would satisfy thermodynamics in terms of the first law (the law of conservation of energy), yet at the same time proves the fallacy of the ‘what you eat and don’t burn, you store’ mantra.
Data from the nutritional literature suggests that different proteins also have quite different biochemical effects and this may affect their weight loss potential. It has been speculated that a rapid delivery of protein, as may occur with hydrolysed protein, may increase the use of component amino acids as a source of energy compared to a slower delivery over a longer range of the postprandial period. This is because hydrolysed protein requires less processing in the gut and so absorption rates are higher, and this leads to larger rises in plasma amino acid levels and a larger release of certain peptides such as gastric inhibitory peptide (GIP; also called glucose-dependent insulinotropic peptide). In addition hydrolysed protein may result in more nitrogen utilisation in the splanchnic region and result in higher rates of amino acid uptake to the skeletal muscle, and this may have anabolic effects. A recent study investigated the physiological effects of hydrolysed casein protein in mice and found beneficial weight loss effect compared to whole intact casein1.
In the study, mice were fed hydrolysed or intact casein protein at two different protein levels (16 and 32 % energy as protein) over 8 weeks. Those mice fed casein protein that had been hydrolysed had higher spontaneous locomotor activity compared to mice consuming intact casein. In addition the mice consuming the hydrolysed casein has lower respiratory exchange ratios, which indicated that they were utilising less carbohydrate as an energy source. Further, the mice fed hydrolysed casein protein also had lower plasma glucose and insulin levels and lower levels of lactate, a metabolite of glucose utilisation. The hydrolysed casein fed mice also showed greater oxidation rates in their inguinal white adipose tissue along with increased expression of genes relating to the oxidation of fatty acids in mitochondria. A decrease in body weight and adipose tissue masses were also observed in the mice fed the hydrolysed casein protein. Therefore hydrolysed casein reduces body weight and improves body composition in mice.
Dr Robert Barrington’s Nutritional Recommendation: Protein is a known weight loss food and high protein diet cause weight loss. Hydrolysed protein may increase the use of amino acids as a fuel source and this may have beneficial weight loss effects compared to the use of carbohydrates. In particular, the rapid delivery of amino acid may present the opportunity for fuel utilisation to shift towards amino acid catabolism and oxidation. These effects are supported by other studies investigating the effects of whey protein in humans. Whey is also a milk protein (like casein) and is often hydrolysed during manufacture. It is known that whey is rapidly delivered to the plasma, where it is oxidised as an energy substrate and also increases the uptake of amino acids to skeletal muscle. Hydrolysed whey protein is therefore recommended as an effective supplement to a high quality fat loss diet.
RdB
