Differences in the findings of studies in this area might be attributable to study design and methodology, diet format and formulation, dog population, and methodology used to
calculate dietary energy content.
Adhering to these traditional concepts the US Department of Agriculture has concluded that diets, which reduce calories, will result in effective weight loss independent of the macronutrient composition, which is considered less important, even irrelevant.14 In contrast with these views, the majority of ad - libitum studies demonstrate that subjects who follow a low - carbohydrate diet lose more weight during the first 3 — 6 months compared with those who follow balanced diets.15, 16, 17 One hypothesis is that the use of
energy from proteins in VLCKD is an «expensive» process for the body and so can lead to a «waste of calories», and therefore increased weight loss compared with other «less - expensive» diets.13, 18, 19 The average human body requires 60 — 65 g of glucose per day, and during the first phase of a diet very low in carbohydrates this is partially (16 %) obtained from glycerol, with the major part derived via gluconeogenesis from proteins of either
dietary or tissue origin.12 The
energy cost of gluconeogenesis has been confirmed in several studies7 and it has been
calculated at ∼ 400 — 600 Kcal / day (due to both endogenous and food source proteins.18 Despite this, there is no direct experimental evidence to support this intriguing hypothesis; on the contrary, a recent study reported that there were no changes in resting
energy expenditure after a VLCKD.20 A simpler, perhaps more likely, explanation for improved weight loss is a possible appetite - suppressant action of ketosis.