In a study of 1,979 overweight and obese adults in the UK, people who lost 5 % or more of their initial
body weight over four years showed significant
changes in markers of physical health, but were more likely to
report depressed mood than those who stayed within 5 % of their original
weight.
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.
And a similar study in The New England Journal of Medicine [2]
reported that «maintenance of a reduced or elevated
body weight is associated with compensatory
changes in energy expenditure, which oppose the maintenance of a
body weight that is different from the usual
weight».