De. Larson et al., SPONTANEOUS OVERFEEDING WITH A CAFETERIA DIET IN MEN - EFFECTS ON 24-HOUR ENERGY-EXPENDITURE AND SUBSTRATE OXIDATION, International journal of obesity, 19(5), 1995, pp. 331-337
OBJECTIVE: To investigate the relationship between obesity and ad libr
tum food intake (quantity and composition) and to assess the impact of
ad libitum food intake on energy expenditure and macronutrient oxidat
ion. DESIGN: Mate volunteers were first fed a weight maintaining diet
for at least 4 days before selecting their food for the next 5 days fr
om two computerized vending machines offering a variety of familiar, p
alatable foods, 24-h energy expenditure (24EE) and substrate oxidation
were measured in a respiratory chamber on the last day of each weight
maintenance and ad libitum intake periods. SETTING: Ten day admission
on a metabolic research ward. SUBJECTS: Thirty-four non-diabetic Pima
Indian males covering a wide range of body weight and body compositio
n (30 +/- 8 y, 102.1 +/- 30.2 kg, 34 +/- 9% body fat, mean +/- s.d.).
RESULTS: Weight maintenance requirements averaged 2913 +/- 342 kcal/d,
Energy intake during the ad libitum period increased to 4550 +/- 921
kcal/d (12 +/- 1% protein, 40 +/- 4% fat, 48 +/- 4% carbohydrate) i.e.
, a spontaneous overeating by 54 +/- 32% above weight maintenance requ
irement, resulting in a 0.9 +/- 1.0 kg body weight gain. Neither the c
omposition of the selected diet nor the degree of overeating was assoc
iated with physical characteristics, such as body weight and body comp
osition, When compared with baseline, spontaneous overeating on day 5
was associated with a 396 +/- 233 kcal/d increase in 24EE, a 607 +/- 5
03 kcal/d increase in carbohydrate oxidation, a 214 +/- 392 kcal/d dec
rease in lipid oxidation (P < 0.01), and no change in protein oxidatio
n. Increased carbohydrate oxidation correlated with the excess carbohy
drate intake (r = 0.69, p = 0.0001) accounting for 68 +/- 13% (mean +/
- s.e.e) of the excess, whereas excess fat intake was not oxidized. CO
NCLUSION: In response to spontaneous overfeeding on a mixed 'cafeteria
diet', excess carbohydrate intake is oxidized, suggesting a physiolog
ical control of carbohydrate stores, whereas excess fat intake is chan
neled toward fat stores, None of the observed changes were related to
indices of obesity.