^{1, 2}

^{1, 3}

^{1, 2}

^{1}

^{1}

^{1}

^{2}

^{3}

^{2}.
REE was estimated by IC and other five equations
of the literature (Harris and Benedict, WHO1, WHO2,
Owen, Mifflin).

Resting energy expenditure (REE) is the major component of total energy expenditure, considering the amount of energy the body requires to keep its vital functions [_{2} and production of CO_{2}. However, due to the high cost of the equipment, equations are usually used to estimate energy expenditure [

Obese persons usually have extremely variable REE and the ideal method to estimate it is still controversial [

Studies available present conflicting results, making it difficult to establish the best formula to estimate total energy expenditure [

Luis et al. studied 200 obese individuals and reported that the equation of the World Health Organization (WHO) [^{2}) [

The equation of Owen et al. [

Based on these data, it can be assumed that there are no definite predictive equations of REE which are suitable to the BMI of the individuals. Therefore, the objective of the present study was to compare values from predictive equations of REE with those from indirect calorimetry in overweight/obesity adults.

A descriptive cross-sectional study was conducted in a subgroup of participants clinically screened for the lifestyle modification program “

The following inclusion criteria were used: sedentary individuals, BMI ≥ 25 kg/m^{2}, and ages between 30 and 60 years old. A total of 82 participants were studied, 40 of them were male and 42 were female. All individuals were overweight or obese adults. The participants characteristics are shown in Table

Distribution of variables according to gender.

Total ( | Men ( | Women ( | |
---|---|---|---|

Age (years) | |||

Weight (kg) | |||

Height (cm) | |||

BMI (kg/m^{2}) | |||

REE (IC) (kcal/d) |

All the subjects signed a free consent form, and the research project was approved by the Research Ethics Committee. The studied patients were part of projects approved by the Ethics Research Committee of the Medical School of Botucatu-UNESP (April 5th, 2004—resolution 196 of October 10th, 1996).

Body mass (kg) was measured using platform-type anthropometric scale (Filizola, Brasil), with graduation of 0.1 kg, 150 kg capacity. Height (m) was determined by portable wall-mounted stadiometer (SECA) with 0.1 cm accuracy. The BMI was calculated using the relation body mass (kg)/height^{2} (m) according to the World Health Organization [

REE was evaluated by indirect calorimetry of open circuit using the mixing-chamber system, with Quinton equipment (QMC). The machine was turned on 30 minutes before the exams for warm-up, suitable stabilization, and calibration of the O_{2} and CO_{2} analyzers with known gas concentration [_{2} and VCO_{2} were measured for a period of 20 minutes [

Demographic and anthropometric data were used to calculate REE using predictive equations of Mifflin et al. [

Equations used to compare REE with values of indirect calorimetry.

Authors | Equations |
---|---|

Mifflin et al. [ | ♂ (9.99 × W) + (6.25 × H) − (4.92 × A) + 5 |

♀ (9.99 × W) + (6.25 × H) − (4.92 × A) − 161 | |

Harris and Benedict [ | ♂ 66.47 + (13.75 × W) + (5 × H) − (6.75 × A) |

♀ 655.0955 + (9.5634 × W) + (1.8496 × H) − (4.6756 × A) | |

FAO/WHO/UNU [ | |

♂ (11.6 × W) + 879 | |

♀ (8.7 × W) + 829 | |

♂ (11.3 × W) + (16 × H (m)) + 901 | |

♀ (8.7 × W) − (25 × H (m)) + 865 | |

Owen et al. ([ | ♂ 879 + (10.2 × W) |

♀ 795 + (7.18 × W) |

W = weight (kg), H = height (cm), A = age (years).

The results were shown as mean ± standard deviation. Anova one-way was used in order to compare the differences between REE values from equations and indirect calorimetry, then Scheffe

Intraclass correlation coefficient and Bland-Altman plot were used to compare the differences between REE values from equations and indirect calorimetry. Significance level was at

For overweight and obese persons of this study, all equations had different values when compared to those of indirect calorimetry. However, the values were similar among Harris-Benedict’s, WHO1 and WHO2’s equations and between Mifflin’s and Owen’s equations (Table

Comparison of REE values from predictive equations and indirect calorimetry.

REE (IC) | Mifflin | Harris and Benedict | WHO1 | WHO2 | Owen | |
---|---|---|---|---|---|---|

Total | 1896 ± 418^{a} | 1607 ± 304^{b} | 1718 ± 329^{c} | 1756 ± 303^{c} | 1765 ± 310^{c} | 1607 ± 284^{b} |

Men | 2128 ± 35^{a} | 1820 ± 233^{b} | 1940 ± 302^{c} | 1993 ± 340^{c} | 2014 ± 334^{c} | 1851 ± 185^{b} |

Women | 1675 ± 356^{a} | 1405 ± 213^{b} | 1508 ± 184^{c} | 1531 ± 141^{c} | 1528 ± 140^{c} | 1374 ± 117^{b} |

Different letters =

^{
a}, ^{b}, ^{c}Anova one-way and Sheffe post-hoc test.

The values of REE obtained from the equations and indirect calorimetry had a strong and significant positive correlation (

Correlation of REE values from predictive equations and indirect calorimetry.

Mifflin | Harris and Benedict | WHO1 | WHO2 | Owen | |
---|---|---|---|---|---|

Harris and Benedict | 0.99 | ||||

WHO1 | 0.96 | 0.97 | |||

WHO2 | 0.96 | 0.97 | 1.00 | ||

Owen | 0.95 | 0.95 | 0.99 | 0.99 | |

REE (IC) | 0.80 | 0.78 | 0.79 | 0.78 | 0.78 |

All values were statistically significant (

The equations underestimated IC by 5% to 12%, in which WHO1, WHO2, and Harris and Benedict were the equations which least underestimated the real value of REE as follows: −5.15%, −4.7%, and −7.43%, respectively. The equations of Owen (−13.28%) and Mifflin (−13.56%) were those which most underestimated REE value. No significant difference was found between genders (data not shown).

For the equations studied, only WHO1 and WHO2 showed values of confidence interval for percent mean difference (CI 95% d%) below 10% and lower values of limits of agreement for percent mean difference (LA 95% d%), reflecting lower systematic error and random, respectively. However, the precision values (LA 95% d%) were high for all equations (Table

Analysis of the intraclass correlation coefficient (ICC) and Bland-Altman plot of predictive equations for REE.

Equations | ICC | ICC CI 95% | d | CI 95% d | SD d | LA 95% | d% | CI 95% d% | SD d% | LA 95% d% |
---|---|---|---|---|---|---|---|---|---|---|

Harris and Benedict | 0.76 | 0.65; 0.84 | −177.8 | −235.8; −120.5 | 260.6 | −688.6; 333.1 | −8.9 | −12.3; −5.5 | 15.3 | −39.0; 21.2 |

Mifflin | 0.76 | 0.65; 0.84 | −289.1 | −344.8; −233.3 | 250.6 | −786.4; 208.1 | −15.6 | −18.9; −12.3 | 14.8 | −44.8; 13.4 |

Owen | 0.72 | 0.60; 0.81 | −289.3 | −348.1; −230.6 | 267.2 | −813.2; 234.4 | −15.4 | −18.8; −12.0 | 15.3 | −45.5; 14.7 |

WHO1 | 0.75 | 0.64; 0.83 | −139.9 | −196.8; −83 | 259.0 | −647.6; 367.7 | −6.4 | −9.8; −3.2 | 15.1 | −36.0; 23.0 |

WHO2 | 0.75 | 0.64; 0.83 | −131.3 | −188.4; −74.1 | 260.0 | −640.8; 378.2 | −6.0 | −9.4; −2.7 | 15.1 | −35.7; 23.6 |

ICC = intraclass correlation coefficient; ICC CI 95% = confidence interval for ICC; d (mean difference); CI 95% for d = confidence interval for mean difference; SD = standard derivation; LA 95% = limits of agreement for mean difference; d% = percent mean difference.

Equations with the following variables—age, gender, BMI, body weight, and height—were proposed. The equations with the best association with indirect calorimetry were those which included weight and gender without (

Predictive equations proposed in this study using age, gender, BMI, height, and body weight variables.

Equations | Standard | |||
---|---|---|---|---|

Age (years) | REE = 2250 − (7.9 × A) | 0.02 | 0.16 | — |

Gender (1 = ♂ and 0 = ♀) | REE = 1675.2 + (453.2 × G) | 0.30 | <0.01 | 353.2 |

BMI | REE = 809.7 + (33.8 × BMI) | 0.18 | <0.01 | 381.7 |

Height (cm) | REE = −2192.1 + (24.8 × H) | 0.45 | <0.01 | 311.4 |

Weight (kg) | REE = 368.9 + (17.4 × W) | 0.60 | <0.01 | 267.3 |

Weight + Gender | REE = 475.3 + (14.9 × W) + (235.8 × G) | 0.67 | <0.01 | 245.3 |

Weight + Gender + Height | REE = −245.3 + (13.6 × W) + (165.8 × G) + (5.3 × H) | 0.67 | <0.01 | 244.6 |

Weight + Gender + Height + Age | REE = −795.9 + (14.5 × W) + (127.3 × G) + (6.5 × H) + (6.1 × A) | 0.68 | <0.01 | 241.7 |

W = weight (kg), H = height (cm), A = age (years), G = gender in which 1 = male and 0 = female, BMI = Body Mass Index.

For overweight and obese individuals, an underestimation of REE by 167.4 kcal (8.83%) was observed using all the equations tested in this study. Both equations of WHO and the equation of Harris and Benedict were those which least underestimated the values of IC, while the equations of Owen and Mifflin were those which most underestimated it. The selection of these equations is due to the fact that they are the most used equations in the general population, and that they have already been evaluated in another Brazilian studies [

Fett et al. conducted a study comparing the same predictive equations of the present study with the REE measured by indirect calorimetry. Women whose BMI ranged from normal weight to obese with mean value of BMI, classified as overweight, were selected for the study [

Another study has also corroborated our findings. Luis et al. studied 200 obese individuals and reported that the equations of Owen, Harris, and WHO underestimated REE and the best equation was WHO [

However, other studies have shown opposite results. Women aged 20 to 40 years old with mean BMI classified as overweight presented overestimation of REE when compared to that of Harris’ and WHO’s equations [

The equations which most underestimated the population of the present study were Mifflin and Owen. The Mifflin’s equation was developed using data collected from 498 individuals classified as normal, overweight, obese, or seriously obese [^{2} and aged 16 to 65 years old [

We suggested a proposal equation for overweight/obese adults, but this new equation needs to be validated in another sample of overweight/obese Brazilian individuals (second validation).

The present study had some limiting factors. Only BMI was used to evaluate body composition of the individuals. Although the lean body mass is the major component of REE, its usage has no additional benefits in predicting REE [

No predictive equations of the literature used in this study had the same values of REE as compared to those of indirect calorimetry, and those which least underestimated REE were the equations of WHO1, WHO2, and Harris and Benedict. The next step would be to validate the new equation proposed.

Resting energy expenditure

Indirect calorimetry

Body mass index

Weight

Gender.

No conflict of interests was reported by the authors.

The authors gratefully acknowledge the financial support of CAPES and CNPq and GAP (Grupo de Apoio à Pesquisa) of the Botucatu School of Medicine for the English assistance.