Metabolic effects of altering the 24 h energy intake in man, using direct and indirect calorimetry

Abstract

I. The metabolic effects of increasing or decreasing the usual energy intake for only I d were assessed in eight adult volunteers. Each subject lived for 28 h in a whole-body calorimeter at 26" on three. separate occasions of high, medium or low energy intake. Intakes (meanfsm) of 13830f475 (high), 8400*510 (medium) and 3700f359 (low) kJ/24 h were eaten in three meals of identical nutrient composition.2. Energy expenditure was measured continuously by two methods: direct calorimetry, as total heat loss partitioned into its evaporative and sensible components; and indirect calorimetry, as heat production calculated from oxygen consumption and carbon dioxide production. For the twenty-four sessions there was a mean difference of only 1.zfo.14 (SEM) % between the two estimates of 24 h energy expenditure, with heat loss being less than heat production. Since experimental error was involved in both estimates it would be wrong to ascribe greater accuracy to either one of the measures of energy expenditure.3. Despite the wide variation in the metabolic responses of the subjects to overeating and under-eating, in comparison with the medium intake the 24 h heat production increased significantly by 10 % on the high intake and decreased by 6 % on the low intake. Mean (~S E M ) values for 24 h heat production were 8770f288, 7896f297 and 7495f253 kl on the high, medium and low intakes respectively. The effects of overeating were greatest at night and the resting metabolic rate remained elevated by 12 % 14 h after the last meal. By contrast, during undereating the metabolic rate at night decreased by only I %. 4. Evaporative heat loss accounted for an average of 25 % of the total heat loss at each level of intake. Changes in evaporative heat loss were f14 % on the high intake and -10 % on the low intake. Sensible heat loss altered by +9 % and -5 % on the high and low intakes respectively. 5.It is concluded that (a) the effects on 24 h energy expenditure of over-feeding for only I d do not differ markedly from those estimated by some other workers after several weeks of increasing the energy intake; (b) the resting metabolic rate, measured at least 14 h after the last meal, can be affected by the previous day's energy intake; (c) the zone of ambient temperature within which metabolism is minimal is probably altered by the level of energy intake.There is considerable disagreement about the metabolic effects of over-eating in man. The controversy is concerned particularly with the effect on the resting metabolic rate (RMR) at least 1 2 h after the last meal: some workers (Miller et al. 1967;Strong et al. 1967) reported no change, while others (Durnin & Norgan, 1969; Apfelbaum et al. 1971) reported an increase after several weeks of over-feeding. There is also much interest in the extent to which some people may adapt to over-feeding by increasing their energy expenditure so that there is little or no increase in weight or less weight gain than expected. Owing to inadequate methodology, many studies on the effects of an altered ...

Changes in energy metabolism in response to 48 h of overfeeding and fasting in Caucasians and Pima Indians

“…25 Although the well-known methodological limitations in quantifying the thermic effect of food and physical activity-related energy expenditure in a respiratory chamber 36 prevented us from delineating the exact contributions of these factors to the overall increase in 24-EE in this small number of subjects, our results indicate that the major effect was attributable to an increase in SMR. In agreement with the study by Dauncey,17 SMR was increased by as much as 19% in the present study, indicating that the effect of overfeeding to increase metabolic rate was sustained for at least 12 h and in fact most prominent in the postabsorptive period. In accordance with ®ndings by Roberts et al, 20 overfeeding induced no detectable change in PA-EE.…”

“…On average, it appears that the decrease in SMR in response to fasting was less pronounced than the decrease in 24-EE ( Figure 1) and even absent in lean individuals and in Caucasians (Figure 2). Although this ®nding seems to agree with the study by Dauncey, 17 it was largely attributable to two lean Caucasians who showed a paradoxical increase in SMR in response to fasting. By de®nition, the lack of a thermic effect of food must also have contributed to the overall decrease in 24-EE in response to fasting.…”

“…These studies give only limited information, however, as to whether these metabolic responses differ between lean and obese individuals 16,18,19 or between populations with different propensity for obesity. Moreover, since only a few studies included a combined overand underfeeding regimen, 17,23,24 it is not clear how the metabolic responses to over-and underfeeding relate to one another within the same individuals.…”

ROLE OF ACTIVITY‐INDUCED THERMOGENESIS IN TWENTY‐FOUR HOUR ENERGY EXPENDITURE OF LEAN AND GENETICALLY OBESE (OB/OB) MICE

“…Motor activity was monitored by two methods while the subject occupied the respiration chamber, one visual (Dauncey, 1986) and the other using a modified Doppler-type burglar alarm (Heal, 1975). The visual estimates of activity agreed with those from the Doppler meter which has already been used in this laboratory for work with rats (Flint, Heap, Ingram & Walters, 1986), pigs (Ingram, Walters & Legge, 1980) and humans (Dauncey, 1980 Over short periods, the visual method gives more detailed information than the Doppler method (Dauncey, 1986). However, for the present investigation, over 24 h periods, the non-subjective Doppler system was the method of choice.…”

Energy balance in a respiration chamber: individual adjustment of energy intake to energy expenditure

“…Using a respiration chamber, energy expenditure can be measured with an accuracy of about 2%. 18 Calculated energy intake, using food composition tables, has also an accuracy of about 2%. 19 Together, the accuracy with which energy balance can be measured is within 4%.…”