908 Am J C/in Nuir l989;50:908-l4. Printed in USA. © 1989 American Society for Clinical Nutrition

Diurnal variation in postabsorptive resting metabolic rate anddiet-induced �2

Jan A Weststrate, Peter JM Weys, Eric J Poortvliet, Paul Deurenberg, andfoseph GAJ Hautvast

ABSTRACT Postabsorptive resting metabolic rate (RMR) and diet-induced thermogene-sis (DIT) were repeatedly assessed on different days in 10 young men of normal weight onmornings and afternoons. No significant diurnal variation was found in RMR, DIT, total

postprandial substrate oxidation, and overall postprandial nutrient balances. The pattern ofpostprandial substrate oxidation indicated an increased glucose oxidation in the first hour afteringestion ofa meal on morning tests compared with afternoon tests. This was probably relatedto differences in the degree ofthe postabsorptive state, ie, 12-14 h on morning tests and 6-7 hon afternoon tests. Am J Clin Nutr l989;50:908-14.

KEY WORDS Resting metabolic rate, diet-induced thermogenesis, diurnal variation, sub-

strate oxidation

Introduction

Rhythmic variations in energy metabolism are welldocumented for animals (1). Cyclical changes in energymetabolism have also been postulated for man (1).Among them, changes in energy expenditure during themenstrual cycle have been studied frequently (2-5). Less

information is available for man on variations in energymetabolism during the day, ie, on diurnal variation inenergy expenditure (6-8). It is well known that energyexpenditure varies during the day because ofthe thermiceffects offood and physical activity (9). Very few investi-gators, however, have studied changes in energy expendi-ture during the day in the absence ofthermogenic stimuli(6-8). In addition, no studies report on diurnal variationof energy metabolism in response to thermogenic stim-uli. In previous studies on man, evidence was obtainedfor a gradual increase during the day in postabsorptiveresting energy expenditure, ie, in postabsorptive restingmetabolic rate (RMR) (6-8). More recent studies do notsupport these findings(lO-l3). In these studies, however,diurnal variation in postabsorptive RMR was not themain objective ofstudy and energy expenditure was usu-ally measured during the morning only.

It is important to clarify the issue ofdiurnal variationin energy expenditure because this may affect the inter-pretation of studies on diet-induced thermogenesis(DIT). DIT can be defined as the increase in energy ex-penditure caused by ingestion of food. Frequently instudies on DIT, a noncaloric control or sham feeding testis used to adjust for possible diurnal variation in postab-sorptive resting energy expenditure (10-1 3). However,other investigators assume no significant changes in post-

absorptive RMR during the day and do not report suchsham feeding tests (14-17).

Besides diurnal variation in resting energy expenditurein the absence of food, changes during the day in the re-

sponse ofenergy metabolism to food may be important.Diurnal variation in the response of energ�i metabolismto food may affect daily nutrient and energy balance.

This study was designed to investigate whether re-peated measurements of postabsorptive RMR and DITvaried systematically with time of the day, ie, betweenmornings and afternoons. No significant diurnal vana-tion in postabsorptive RMR and DIT was found butpostprandial substrate oxidation showed a different pat-tern in the morning than in the afternoon.

Methods

Subjects

Ten young men, all students, participated in the study. Dataconcerning some physical characteristics and age are presentedin Table 1. Each individual was fully informed about the natureand purpose of the experiment before giving his written con-sent to participate and the study was conducted according tothe standards ofthe Medical-Ethical Committee ofthe Depart-ment of Human Nutrition of the Wageningen Agricultural

I From the Department of Human Nutrition, Wageningen Agricul-tural University, 6703 BC Wageningen, The Netherlands.

2 Address reprint requests to JA Weststrate, Department of Human

Nutrition, Wageningen Agricultural University, Bomenweg 2, 6703

HD Wageningen, The Netherlands.ReceivedFebruary 16, 1988.Accepted for publication May 31, 1988.

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DIURNAL VARIATION IN THERMOGENESIS 909

TABLE 1Age and some physical characteristics ofthe subjects

Subject Age Weight Body mass index Fat-free mass Percent body fat

y kg kg/rn2 kg %

1 22 65.5 21.7 53.9 17.6

2 20 86.1 25.9 71.3 17.1

3 23 74.3 21.8 59.9 19.3

4 20 78.9 21.3 68.0 13.7

5 21 75.2 21.4 61.7 17.9

6 24 74.9 22.8 61.9 17.3

7 25 79.4 22.0 69.5 12.5

8 22 65.2 19.5 59.9 7.8

9 23 71.9 22.2 64.5 10.3

10 22 83.5 24.4 69.1 17.2

i�±SEM 22±0.5 75.4±2.2 22.3±0.6 64.0±1.7 15.1± 1.2

University. None ofthe subjects was on a special diet and none

of the subjects was using any medication at the time of thestudy. All subjects were nonsmokers and apparently healthy asassessed by medical questionnaire.

Experimental design

Postabsorptive RMR was measured six times on differentdays in each subject, three times in the morning and, similarly,three times in the afternoon. Between each session there was atime span of � 2 d. All subjects completed the experiment in 4wk. Morning RMRs were measured with the subject in a 12-14 h postabsorptive state. Afternoon RMRs were measuredwith the subject in a 6-7 h postabsorptive state. At the day ofthe afternoon sessions the subjects were allowed to have a smallnormal Dutch breakfast of -.-480 kcal (2000 Id) (10% protein,35% fat, and 55% carbohydrates) between 0745 and 0800. Thesubjects were instructed to refrain from sleeping, drinkingcoffee, and moderate to heavy physical activity on the morn-ings before the afternoon tests. The order of RMR measure-ments was randomized between the morning and afternoontests.

On two mornings and on two afternoons after the RMRmeasurement, energy expenditure in response to a meal wasmeasured in each subject to assess DIT. The increase in RMRdue to the ingestion ofthe meal was defined as DIT. The mealwas a yogurt-based liquid formula containing on average 456kcal (1906 Id) (10% protein, 33% fat, and 57% carbohydrates).The order of the DIT measurements was randomized betweenthe morning and afternoon tests. To familiarize the subjectswith the equipment for measuring RMR and DIT, resting en-ergy expenditure was measured in each subject on a separateday before the start ofthe experiment for “�-30-45 mm.

Gas exchange measurements

Postabsorptive resting metabolic rate. On the day of eachRMR measurement, the subjects were taken to the laboratoryby car. After voiding they lay supine but awake on a hospitalbed. After a 30-mm rest, RMR was continuously measured be-tween 0800 and 0900 in the morning or 1400 and 1500 in theafternoon at an environmental temperature of 23-25 #{176}C.Dur-ing the RMR measurements the subjects watched video films.

Postprandial energy expenditure. After the RMR measure-ment the subjects were given the test meal; 5 mm after they hadfinished eating the test meal, energy expenditure was measured

continuously for 4 h. During the postprandial energy expendi-ture measurements the subjects watched video films. Roomtemperature was always kept at 23-25 #{176}C.The subjects wereinstructed to be as relaxed as possible and to minimize move-ments. After the gas exchange measurements, urine was col-lected for determining urea nitrogen.

All gas exchange measurements were performed by use of aventilated-hood system. A transparent perspex ventilated hoodwas placed over the subjects head and made airtight around theneck. A pump(Ocean SCL21O, Dieren, The Netherlands) drewfresh outside air through the hood. The flow rate through thehood was measured by a thermal mass flowmeter (Model58l2N, Brooks, Veenendaal, The Netherlands). The flow ratewas kept between 30 and 40 L/min by an electrically operatedcontrol valve (model 5837, Brooks). A small sample of ‘�0.3L/min ofthe air leaving the hood was analyzed for oxygen andcarbon dioxide content by, respectively, a paramagnetic 02 an-alyzer, adjusted to a full scale range of 20-21% (Servomex,1 100A, Zoetermeer, The Netherlands) and an infrared CO2 an-alyzer, full scale range 0-1% (Analytical Development Com-pany, 55100, Hoddesdon, UK). The analyzers were calibratedeach morning or afternoon session by using dried gas mixtureswith known 02 and CO2 contents. 02 and CO2 concentrationsin dried fresh outside air were measured every 30 mm duringthe RMR measurement and every hour during the postpran-dial energy expenditure measurements for 5 mm. Air flow rate

and 02 and CO2 concentration ofthe inflowrng and outfiowingair were computed on line by an automatic data acquisitionunit (model 3497A, Hewlett-Packard Co, Palo Alto, CA) inter-faced to a microcomputer (model 85, Hewlett-Packard Co).The outputs of the gas analyzers and the flowmeter were alsocontinuously recorded by a multipen recorder (Kipp & ZonenBDlOl, Delft, The Netherlands). 02 and CO2 concentrationsof the outflowing air and air flow rate through the hood weremeasured every 30 s and integrated over 5-mm intervals to ob-thin 02 consumption, CO2 production, respiratory quotient(RQ), and metabolic rate according to equations described byJ#{233}quier(18).

Cakulation ofdiet-induced thermogenesis andsubstrate oxidation

02 consumption and CO2 production were corrected formovements of the subjects when necessary. To obtain themean resting energy expenditure for each hour after ingestion

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910 WESTSTRATE ET AL

of the test meal, 02 consumption and CO2 production wereaveraged over each hour by using the 5-mm interval data.These values were used to calculate the average DIT for theindividual hours after the test meal and for the total mean DITover 4 h. DIT was calculated by subtracting the RMR valuefrom the respective average hourly or total mean postprandialenergy expenditure. The DIT is expressed as a percentage ofthe energy content ofthe test meal.

Protein oxidation was estimated by determination of un-nary urea N excretion, with a test kit (kit 396346, BoehringerMannheim BV, Almere, The Netherlands) according to Gut-man and Bergmeyer(l9). Carbohydrate and fat utilization dur-ing RMR and during the 4 h after ingestion of the test mealwere calculated by use ofthe nonprotein RQ (18). 02 and CO2equivalents for substrate oxidation before and after the inges-tion ofthe test meal were obtained from Lillioja et al (20). Car-bohydrate oxidation was corrected for net de novo lipogenesisfrom glucose as previously described (17). A nonprotein RQ> 1 .00 indicated net de novo lipogenesis, ie, lipogenesis ex-ceeding concomitant fat oxidation.

Both’ composition

Fat-free mass was estimated by densitometry. Total body

density of each subject was measured once during the expeni-ment in duplicate by the underwater weighing method with si-multaneous measurement ofthe residual lung volume by a he-hum dilution technique. Fat-free mass was calculated from to-tal body density by using Siri’s equation (21).

Statistics

The results are expressed as mean ± SEM. Analysis of vari-ance and use of the model for a single factor experiment withrepeated measurements was used to test whether RMR andDIT varied systematically between mornings and afternoons.Paired two-tailed Student’s I tests were performed to evaluatedifferences in mean RMR, DIT, and substrate oxidation ratesbetween morning and afternoon sessions. Confidence intervalswere used to express mean differences in RMR, DIT, and sub-strate oxidation rates between morning and afternoon sessions.Pearson’s product-moment correlation coefficients were usedin correlation analyses (22).

Results

Table 1 shows that all subjects had body weights andbody fat percentages within the normal range. Table 2gives postabsorptive RMRs in subjects, separately for themorning and afternoon sessions. Analysis of variance

showed no significant day and time of day effect onRMR. The 95% confidence interval for the averagedifference between the mean morning and afternoon val-ues in RMR is -0.02 to +0.08 kcal/min (-0.07 to +0.35kJ/min). Therefore, for each person the mean morningand afternoon RMR values were used in subsequentanalyses. Morning RMRs were significantly correlatedwith afternoon RMRs, (r = 0.95, p < 0.01). RMR valuesexpressed on a fat-free mass basis (kg FFM) were 25.9± 0.6 kcal.d� .kgJ�J�4’ (105.4 ± 2.6 kJ.d’ .kgFFM�’)on mornings and 25.2 ± 0.6 kcal.d’.kgFFM’ (105.4± 2.6 Id . d ‘ . kgFFM ‘) on afternoons.

Data on DIT in subjects over 4 h after ingestion of ameal at different times of the day are presented in Table

3 separately for mornings and afternoons. Analysis ofvariance showed no significant effect ofday and time ofday on total DIT. Therefore, for each person the meanmorning and afternoon DIT values were used in subse-quent analyses. The 95% confidence interval for themean difference between the morning and afternoonDIT values was - 1 .8% to +2.6% of the energy contentofthe test meal, ie, -8.1 to +12.0 kcal (-34 to +50 kJ).Average morning DIT values were significantly corre-lated with average afternoon DIT values (r = 0.89,p < 0.01).

Figure 1 shows DIT separately for each hour after in-gestion of the meal in subjects on morning or afternoontests. No significant effect of time of day on the meanhourly DIT values was observed. On average, DIT wasslightly higher on morning sessions in the first hour afteringestion ofthe meal in comparison with afternoon ses-sions, whereas for the third and fourth hour the oppositewas true. The average DIT in the fourth hour after theingestion ofthe test meal was �.-0.02 kcal/min (‘��.-0. 1 kJ/mm) (2-3%) above the corresponding postabsorptive

RMR on morning sessions and ‘��-�0.05 kcal/min (-‘--0.2kJ/min) (4-5%) above the corresponding postabsorptiveRMR on afternoon sessions.

Figure 2 represents RQs in subjects before and afteringestion ofa test meal at different times ofthe day. RQswere significantly higher on mornings in the first hourafter ingestion ofthe meal in comparison with afternoonRQs. The reverse was true for the third and fourth hourafter ingestion ofthe test meal.

Table 4 gives carbohydrate and fat oxidation in sub-

jects before and after ingestion of a meal, separately forthe morning and afternoon sessions. The results are ex-pressed in absolute amounts and as a percentage of totalenergy expenditure. Before ingestion of the test meal,during the RMR measurement, no significant differ-ences were observed in relative or absolute amount ofoxidation ofthese nutrients between morning and after-noon. Carbohydrate oxidation was significantly higherand fat oxidation significantly lower on mornings in thefirst hour after ingestion of the test meal than on after-noons. During the third and fourth hour postprandially,carbohydrate oxidation was lower in the morning incomparison with the afternoon, in contrast to fat oxida-tion. Protein oxidation was estimated for each sessionby the average (5.5 h) urinary urea N excretion. Protein

oxidation was not significantly different between morn-ing tests and afternoon tests, 57 ± 3 vs 53 ± 3 mg/mini.

Table 5 shows energy and nutrient balances in subjects

after ingestion of meals at different times of the day. Nosignificant differences between morning and afternoontests in total oxidation and storage or balance ofthe van-ous nutrients were observed but on average, energy bal-ance, ie, energy retention, was slightly higher on after-noon than on morning sessions. The 95% confidence in-terval for the mean difference in energy retentionbetween morning and afternoon tests is -0.02 to +3 1.8

kcal (- 1 to + 1 33 Id). Net de novo lipogenesis from car-bohydrates did not differ between mornings and after-

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morning�: afternoon

1-4

DIURNAL VARIATION IN THERMOGENESIS 911

TABLE 2Postabsorptive resting metabolic rate in subjects at different times ofthe day*

Subject Morningt Afternoonf Totalt

kca//min (kJ/min)

1 1 .06 ± 0.03 (4.45 ± 0. 1 1) 1 .09 ± 0.02 (4.54 ± 0.07) 1 .08 ± 0.0 1 (4.50 ± 0.06)

2 1 .40 ± 0.06 (5.87 ± 0.24) 1 .30 ± 0.02 (5.45 ± 0.07) 1 .35 ± 0.04 (5.66 ± 0.15)

3 1.10±0.06(4.61 ±0.27) 1.13 ±0.08(4.74 ±0.35) 1.12 ±0.05(4.68 ±0.20)

4 1.30 ± 0.08 (5.43 ± 0.35) 1.15 ± 0.08 (4.82 ± 0.33) 1.22 ± 0. 15 (5. 12 ± 0.62)

5 1.09 ± 0.01 (4.56 ± 0.06) 1.03 ± 0.05 (4.3 1 ± 0.20) 1 .06 ± 0.04 (4.43 ± 0. 1 1)

6 1 .08 ± 0.06 (4.52 ± 0.24) 1 . 1 1 ± 0.06 (4.66 ± 0.26) 1 .09 ± 0.04 (4.58 ± 0.16)7 1.25 ± 0.03 (5.24 ± 0. 1 1) 1 . 12 ± 0.03 (4.69 ± 0. 1 1) 1 . 19 ± 0.03 (4.96 ± 0.14)8 1 .04 ± 0.07 (4.37 ± 0.28) 1 .07 ± 0.0 1 (4.47 ± 0.04) 1 .06 ± 0.03 (4.42 ± 0.13)

9 0.98 ± 0.05 (4.09 ± 0.21) 1.00 ± 0.01 (4.19 ± 0.05) 0.99 ± 0.02(4.14 ± 0.10)

10 1.20±0.01 (5.02 ±0.04) 1.16 ±0.01 (4.87 ±0.04) 1.18±0.01(4.94±0.04)1± SEM 1 . 1 5 ± 0.04 (4.8 1 ± 0. 1 8) 1 . 12 ± 0.03 (4.67 ± 0. 1 1) 1 . 13 ± 0.04 (4.74 ± 0.15)

*�±5EM

t Mean ofthree measurements.:1:Mean ofsix measurements.

noons. On average < 3% of the ingested carbohydrateswas converted to fat.

Discussion

This study was designed to determine the effect of time

of the day, morning vs afternoon, on RMR and DIT.The results show no significant diurnal variation in post-

absorptive RMR and DIT. Postprandial substrate oxida-tion was affected by time of the day but this effect was

transient and overall postprandial nutrient balances didnot show significant diurnal variation. Morning and af-ternoon measurements of energy expenditure were per-

TABLE 3Diet-induced thermogenesis in subjects after ingestion ofa meal on

different times ofthe day*

Subject Morningt Afternoont Totalt

%�

I 7.5±0.6 5.2± 1.5 6.3± 1.02 6.9± 1.3 13.6±6.3 10.2± 1.63 7.8±0.7 4.8±1.3 6.3± 1.04 9.3±4.5 9.8± 1.2 9.5± 1.9

5 6.1±0.5 6.4±2.8 6.2± 1.26 6.3±1.4 4.7±1.0 5.5±0.97 5.2±0.9 7.6±3.4 6.4± 1.68 6.3±0.3 5.4±0.5 5.8±0.4

9 7.0±0.8 4.6± 1.2 5.8±0.910 10.2±0.0 6.8±1.6 8.5± 1.2

;:� SEM 7.4 ± 0.5 6.9 ± 0.9 7. 1 ± 0.5

*�±SEM

t Mean oftwo measurements.:1:Mean offour measurements.§ Percent ofenergy content ofmeal. The coefficient ofvariation for

energy intake was -0.5%. Test meal contained 456 kcal (1906 U) onaverage.

formed on different days. In this way, the possibility thatmorning measurements would have a residual effect on

afternoon assessments of energy expenditure was ex-cluded. The design of the study, however, allowed fornormal intraindividual, between-day variation in morn-ing and afternoon RMR and DIT. This may have ob-

scured the finding ofdiurnal variation in RMR and DITof a relatively small magnitude. To minimize this possi-

bility, RMR and DIT were assessed repeatedly both onmornings and on afternoons.

Several investigators have studied, in man, temporal

order in a number of physiological variables. For manyvariables, ie, blood hormone concentrations and urinaryhormone excretions, diurnal rhythms have been well es-

diet - induced thermogenesis Fkccit 1mm]

time after meat ingestion (h)

FIG 1 . Diet-induced thermogenesis in subjects after ingestion of a

meal at different times ofthe day. The bars represent diet-induced ther-

mogenesis (�± SEM) in kcal/min separately for each hour and for the

total period after ingestion ofa meal in the morning or in the afternoon.

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before/aftermeal ingestion (h)

912 WESTSTRATE ET AL

respiratory quotient

FIG 2. Respiratory quotients in subjects before and after ingestionof a meal at different times of the day. The bars represent respiratoryquotient (1± SEM) before (during RMR) and separately for each hourand the total period after ingestion of a meal in the morning or in the

afternoon. Significant difference between morning and afternoon val-

ues, p < 0.05, at 1, 3, and 4 h after meal ingestion.

tablished (23). Information on cyclical changes duringthe day in human energy metabolism is scarce. The firstpart of this study is about diurnal variation in postab-sorptive RMR. Early reports (6-8) show that in manpostabsorptive RMR increases during the day. However,the results of these studies may have been influenced byeffects ofvanation during the measurement period in theduration of the postabsorptive state. Thus, metabolicrate measurements later in the day were usually per-formed in subjects under greater postabsorptive stress.

This may in itselfhave caused the reported increase dur-ing the day in postabsorptive RMR. Despite the absence

ofclear data on diurnal variation in postabsorptive RMRin man, it is generally believed that such variation exists(10-1 3, 24). Obviously, resting energy expenditure variesduring the day because of the thermic effects of feeding(9). In addition, nocturnal RMR may be slightly differentfrom diurnal RMR (25). The question is whether thereis a diurnal rhythm in man in postabsorptive RMR at agiven fasting state. Ifsuch a rhythm exists, its physiologi-cal and biochemical basis could be related to hormonally

mediated changes during the day in energy-demandingprocesses, ie, in sodium pumping or protein synthesis. Atpresent, however, no diurnal variation in turnover ratesof thermogenic hormones has been reported (26) and amechanism for possible diurnal variation in postabsorp-tive resting energy expenditure is unclear.

To study diurnal variation in energy expenditure, oneshould ideally measure postabsorptive RMR in subjectsunder the same conditions at different times of the day.Usually in previous studies on this subject, variation wasintroduced in the duration of the fasting state betweendifferent times of the day (6-1 3). In the present study

morning and afternoon tests also varied in duration of

the postabsorptive state. But in contrast to previous stud-ies, the subjects had a shorter duration of the fast on the

afternoon tests than on the morning tests. This may haveconfounded the afternoon measurements of postabsorp-tive RMR with residual diet (breakfast)-induced thermo-genesis. However, the results show that residual DIT didnot significantly increase afternoon postabsorptiveRMRs in comparison with morning postabsorptiveRMRs. In contrast, on average, RMR was slightly butnot significantly lower on afternoon than on morningtests. The absence ofsignificant diurnal variation in post-absorptive RMR was not due to large interindividualdifferences in response to time of the day of energy me-tabolism because morning RMR values were highly cor-related with afternoon RMR values. In addition, the re-suit of this study agrees with other reports in which, forseveral hours during the morning, no significant effect ofsham feeding was observed on postabsorptive RMR(10-13).

The second part of the study deals with the questionof systematic variation with time of the day in the re-sponse of energy metabolism to food. This question hasnot been addressed before. The results show that the timeofday did not significantly influence DIT. Similar to thefindings for the RMR, this was not due to great interindi-vidual variability in difference in DIT between morning

TABLE 4Mean carbohydrate and fat oxidation in absolute amounts and as apercentage oftotal energy expenditure in subjects before and afteringestion ofa meal at different times ofthe day*

Oxidationduring

Carboh

Morning

ydrates�

Afternoon

Fats

Morning Afternoon

RMR(% kcal/min) 39 39 40 40(mg/mm) 117 115 50 47

PEEl(% kcal/min) 64 57j: 16 24t(mg/mm) 234 l96t 24 33

PEE2(% kcal/min) 66 66 14 14

(mg/mm) 241 226 21 20

PEE3(% kcal/min) 46 54t 33 25t(mg/mm) 152 177 46 34t

PEE4(%kcal/min) 27 37j: 51 42t

(mg/mm) 84 l33f 65 53

PEEt(% kcal/min) 52 54 28 26

(mg/mm) 178 178 39 35

* RMR, postabsorptive resting metabolic rate; PEE, postprandial

energy expenditure (PEEl, during first hour; PEE2, during second

hour; PEE3, during third hour; PEE4, during fourth hour; and PEEt,during total postprandial period).

t Expressed on a glucose basis.t Significantly different from morning values, p < 0.05.

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DIURNAL VARIATION IN THERMOGENESIS 913

TABLESNutrient and energy balance in subjects after ingestion ofa meal at different times ofthe day*

Energy Carbohydrates

Morning Afternoon

Fat Protein

Morning Afternoon Morning Afternoon Morning Afternoon

kca/(k.J) kca/(k.J) g g g g g g

Intake

OxidationExpenditure

Net lipogenesis

Balance

455± 0.7(1902±3)

-

312±12.7(1306±53)-

143± 12.9(597±54)

457± 1.0(1911 ±4)

-

298±10.3(1248±43)-

159± lO.0(664±42)t

69.2±0.1

41.7±3.1-

-

27.5±2.3

69.5±0.2

41.8±2.2-

-

27.7±2.3

16.6±0.0

9.0±1.9-

0.7 ± 0.3

8.4±2.1

16.7±0.0

8.0±1.6-

0.4 ± 0.2

9.2± 1.7

11.7±0.0

13.8±0.8-

-

-2.1 ±0.8

11.7±0.0

12.8±0.7-

-

-1.1 ±0.7

*j±5EM

t Significant difference between morning and afternoon values, p < 0.05 (borderline significance).

and afternoon tests. In addition, it is unlikely that theabsence of diurnal variation in DIT was caused by tooshort a measurement period because mean DIT had de-creased almost to 0 in the fourth hour after ingestion ofthe meal both in the morning and in the afternoon. DITwas assessed without using a noncaloric control test. Ithas been argued (24) that such a test should be used toassess diurnal variation in postabsorptive RMR. How-ever, several investigators (14-17) calculated DIT in thesame way as has been done in this study. Furthermore,if metabolic rate measurements on such tests are con-

founded by variation in the duration ofthe fasting stateduring the test, measured changes in postabsorptiveRMR may be induced by an adaptation to an increas-ingly prolonged fasting state and may not reflect diurnalvariation in postabsorptive resting energy expenditure.In addition, it is a matter of conjecture to infer thatchanges in resting energy expenditure in the absence offood will also occur after ingestion of food.

Total postprandial substrate oxidation and nutrientbalances were not significantly different between morn-ing and afternoon tests. There was, however, a transient

effect of time of the day on substrate oxidation in thefirst, third, and fourth hour after ingestion of the meal.The effect of the time of day on postprandial substrateoxidation is most likely related to differences betweenmorning and afternoon sessions in the duration of thepostabsorptive state. It can be expected that after a fastof 12-14 h, total body glycogen stores are more depletedthan after a fast of 6-7 h. Previous studies in man (27,28) showed that glucose given orally or intravenously is

taken up predominantly by muscle for glycogen synthe-sis. In a more glycogen-depleted state, the activity of gly-cogen synthetase seems increased (29), which may be as-sociated with an enhanced insulin response or insulin ac-tion at the cellular level (30). This may in turn be relatedto an increased glucose oxidation because in the restingstate, glucose oxidation up to concentrations of -‘-4 mg.kg ‘ . min ‘ is associated with increased glucose storage,ie, glycogen synthesis (3 1). Such high rates ofglucose oxi-dation did not occur in this study. Because of the rela-tively increased glucose oxidation in the first hour after

ingestion of the meal, less glucose may be available in

the circulation for oxidation in the third and fourth hourpostprandially. This may enhance fat oxidation to meetthe tissue demands for energy. This mechanism is sup-ported by the findings ofthis study.

In conclusion, we can state that the time of day hadno significant effect on postabsorptive RMR or DIT. Inaddition, no systematic diurnal variation was observedin total preprandial and postprandial substrate oxida-

tion. However, hourly postprandial substrate oxidationindicated an increased glucose oxidation in subjects in amore prolonged fasting state. 13

We thank A Soffers for helping with the urinary urea nitrogen analy-

ses and the volunteers for their kind and enthusiastic participation inthe experiment.

References

I. AschoffJ, PohI H. Rhythmic variations in energy metabolism. Fed

Proc l970;29: 154 1-52.2. Wakeham G. Basal metabolism and the menstrual cycle. J Biol

Chem l923;23:555-67.3. Williams WW. The basal metabolic rate, basal body temperatures,

and the ovarian cycle. Am J Obstet Gynecol 1943;46:662-7.

4. Solomon SJ, Kurzer MS. Calloway DH. Menstrual cycle and basalmetabolic rate in women. Am J Clin Nutr l982;36:61 1-6.

5. Webb P. 24-hour energy expenditure and the menstrual cycle. Am

J Clin Nutr l986;44:6l4-9.6. Benedict FG. Factors affecting basal metabolism. J Biol Chem

19 1S;20:263-99.7. Buskirk ER, Lampietro PF, Welch BE. Variations in resting me-

tabolism with changes in food, exercise and climate. Metabolisml957;6: 144-53.

8. Bailey D, Harry D, Johnson RE, Kupprat I. Oscillations in oxygenconsumption ofman at rest. J Appl Physiol 1973;34:467-70.

9. Woo R, Daniels-Kush R, Horton ES. Regulation of energy bal-

ance. Annu Rev Nutr l985;5:41 1-33.10. ShariefNN, Macdonald I. Differences in dietary-induced thermo-

gensis with various carbohydrates in normal and overweight man.Am J Clin Nutr 1982; 35:267-72.

1 1. Welle S, Campbell RG. Normal thermic effect ofglucose in obesewomen. Am J Clin Nutr 1983;37:87-92.

Downloaded from https://academic.oup.com/ajcn/article-abstract/50/5/908/4695451by gueston 09 February 2018

914 WESTSTRATE ET AL

12. Nair KS, Halliday D, Garrow JS. Thermic response to isoenergetic

protein, carbohydrate or fat meals in lean and obese subjects. ClinSci l983;65:307-l2.

13. Felig P, Cunningham J, Levitt M, Hendler R, Nadel E. Energy

expenditure in obesity in fastingand postprandial state. Am J Phys-iol l983;244:E45-5 1.

14. Schutz Y, Golay A, Felber JP, J#{233}quierE. Decreased glucose-induced

thermogenesisafterweightlossin obese subjects: a predisposing factorfor relapse ofobesity? Am J Gin Nutr 1984; 39:380-7.

15. Tappy L, Randin JP, FelberJP, et al. Comparison ofthermic effectoffructose and glucose in normal humans. Am J Physiol l986;250:

E7l8-24.

16. Illingworth PJ, Jung RT, Howie PW, Isles TE. Reduction in post-

prandial energy expenditure during pregnancy. Br Med J

l987;294: 1573-6.

17. Den Besten C, Vansant C, Weststrate JA, Deurenberg P. Resting

metabolic rate and diet-induced thermogenesis in abdominal and

gluteal-femoral obese women before and after weight reduction.

Am J Clin Nutr 1988;47:840-7.18. J#{233}quierE. Direct and indirect calorimetry. In: Garrow iS, Halliday

D, eds. Substrate and energy metabolism. London: John Libbey,1985:82-92.

19. Gutman I, Bergmeyer HU. Urea. In: Bergmeyer HU, ed. Methods

of enzymatic analysis, 2nd ed. New York: Verlag Chemie Wein-heim and Academic Presslnc, 1974:1791-8.

20. Lillioja 5, Bogardus C, Mott DM, Kennedy AL, Knowler WC,Howard BV. Relationship between insulin-mediated glucose dis-posal and lipid metabolism in man. i Clin Invest l985;75:1l06-

IS.

21. Sin WE. The gross composition ofthe body. Advances in biology

and medical physics. l956;4:239-80.22. Winer BJ. Statistical principles in experimental design. 2nd ed.

New York: McGraw-Hill Book Company, 1971.

23. Halberg F. Chronobiology. Annu Rev Physiol 1969;31:675-725.

24. Garrow iS. Energy balance and obesity in man. 2nd ed. Amster-

dam: Elsevier/North Holland Biomedical Press, 1978.

25. Schutz Y, Bessard T, i#{233}quierE. Diet-induced thermogensis mea-

sured over a whole day in obese and nonobese women. Am i ClinNutr I 984;40:542-52.

26. Greenspan FS, Forsham PH. Basic & Clinical Endocrinology. 2nd

ed. Norwalk: Appleton-Century-Crofts, I 986.

27. DeFronzo RA, Jacot E, i#{233}quierE, Maeder J, Wahren J, Felber iP.The effect ofinsulin on the disposal ofintravenousglucose. Resultsfrom indirect calorimetry and hepatic and femoral venous catheri-zation. Diabetes 198 l;30:l000-7.

28. Katz LD, Glickman MG, Rapoport S. Ferrannini E, DeFronzo

RA. Splanchnic and peripheral disposal of oral glucose in man.

Diabetes 1983; 32:675-9.29. Bogardus C, Thuillez P, Ravussin E, Vasquez B, Narimiga M,

Azhar 5. Effect of muscle glycogen depletion on in vivo insulin

action in man. J Clin Invest 1983;72:1605-10.30. Bogardus C, Lillioja 5, Stone K, Mott D. Correlation between mus-

dc glycogen synthase activity and in vivo insulin action in man. iClin Invest1984;73:l185-90.

31. Thiebaud D, iacot E, DeFronzo PA, Maeder E, i#{233}quierE, FelberJP. The effect of graded doses of insulin on total glucose uptake,glucose oxidation, and glucose storage in man. Diabetes 1982; 3 1:

957-63.

Downloaded from https://academic.oup.com/ajcn/article-abstract/50/5/908/4695451by gueston 09 February 2018