Covert manipulation of energy density of high carbohydrate diets in ‘pseudo free-living’ humans

Abstract

OBJECTIVE: This study examined the effects of varying the energy density (ED) of high carbohydrate (HC) diets on food and energy intake (EI), subjective hunger and body weight in humans. DESIGN: Randomised cross-over design. Subjects were each studied twice during 14 d, throughout which they had ad libitum access to one of two covertly-manipulated diets. 2 ) were studied. The fat, carbohydrate (CHO) and protein content (as % energy) and ED of each diet were 21 : 66 : 13% and 357 kJa100 g, (lowenergy density (LED)) or 22 : 66 : 12% and 629 kJa100 g (high-energy density (HED)). A medium fat diet was provided at maintenance (1.6 Â BMR, MF for 2 d) before each ad libitum period. Subjects could alter the amount, but not the composition of foods eaten. RESULTS: Mean EI was 8.67 and 14.82 MJad on the LED and HED diets, respectively. Subjects felt signi®cantly more hungry on the LED diet, than on the HED diet (F 1,160 38.28; P`0.001) and found the diets to be similarly pleasant (72.72 mm vs 71.54 mm (F 1,392 0.31; P 0.579)). Mean body weight decreased on the LED diet at a rate of 0.1 kgad and increased at 0.06 kgad on the HED diet (F 1,131 86.60; P`0.001), giving total weight changes of 71.41 kg and 0.84 kg, respectively, both of which were signi®cantly different from zero (P`0.01). CONCLUSION: Excess EI is possible on HC, HED diets, at least under conditions where diet selection is precluded.Comparison of these results with previous studies, which altered ED using fat, suggests that CHO may be a better cue for hunger than fat.

Dietary energy density increases during early childhood irrespective of familial predisposition to obesity: results from a prospective cohort study

“…With respect to the current investigation, however, it should be noted that the sample size (n ¼ 49 children) might have been too small to detect significant associations between the two variables. Although laboratory and clinical studies that were conducted in adults showed a positive-association between dietary ED and weight gain, [33][34][35] data from cross-sectional epidemiological studies showed inconsistent results. 36 For example, a recent cross-sectional study in adults showed that normal-weight individuals had diets with a lower ED than did obese individuals.…”

Energy density, energy intake and weight status in a large free-living sample of Chinese adults: exploring the underlying roles of fat, protein, carbohydrate, fiber and water intakes

“…Energy density appears to in¯uence the regulation of energy intake and weight control even under covert conditions when portion size cues or learned behaviors are circumvented (Spiegel, 1973;Garrow et al, 1978;Stubbs et al, 1998;Stubbs et al, 1995a,b;Lissner et al, 1987;Kendall et al, 1991). The underlying biological mechanism must therefore involve regulatory processes.…”

“…Given that previous researchers have reported shifts in fat, protein, carbohydrate, ®ber and water intakes with changes in energy density (Lissner et al, 1987;Stubbs et al, 1998), these nutrients were identi®ed as potential correlates andaor determinants of energy density. Each of these nutrients contributes to energy intake or to the bulk, weight or volume of the food consumed.…”

“…The management of weight maintenance andaor weight loss may be achieved by eating a diet of low energy density (p 169)'. Results from existing clinical studies of covertly manipulated energy density (Spiegel, 1973;Garrow et al, 1978;Stubbs et al, 1998;Stubbs et al, 1995a,b;Lissner et al, 1987;Kendall et al, 1991) show a positive association between energy density and weight change. If energy density consistently predicts energy intake and weight change, what then is the underlying mechanism?…”

“…Lissner et al (1987) report shifts in macronutrient composition from 30 ± 35%, 12% and 55% of energy from fat, protein and carbohydrate, respectively, on the medium-fat diet to 15 ± 20%, 13% and 70% of energy on the low-energy dense diet, to 45%, 10% and 42% of energy on the high-energy dense diet, respectively. Using thickening agents in their dietary manipulations, Stubbs et al (1998) found signi®cant changes in water and ®ber intakes, as well as protein, fat and carbohydrate intakes. Since any of the component alterations could ultimately be responsible for the observed effects, it is not clear what mechanism mediates the effects of energy density.…”