Unintended Weight Loss in Older Adults

UWL: Caloric Needs (2007)


Rizzo MR, Mari D, Barbieri M, Ragno E, Grella R, Provenzano R, Villa I, Esposito K, Giugliano D, Paolisso G.  Resting metabolic rate and respiratory quotient in human longevity.  J Clin Endocrinol Metab 2005;90(1):409-13.

PubMed ID: 15483081
Study Design:
Cross-Sectional Study
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To investigate the relationship between energy expenditure and longevity by evaluating RMR and RQ in human longevity.

Inclusion Criteria:
  • Stable body weight (+/- 2 kg) in last 6 months
  • No smoking
  • Liver, kidney and thyroid functions within normal range
Exclusion Criteria:
  • Hypertensive and diabetic patients
  • Subjects with secondary or Alzheimer's dementia
  • Using medications affecting body composition or RMR or RQ
  • All subjects that conducted a vigorous physical activity as well as subjects confined to bed
Description of Study Protocol:


Subjects volunteered for the study.

Design:  Cross-Sectional Study 

Blinding used (if applicable):  not applicable

Intervention (if applicable):  not applicable 

Statistical Analysis

ANOVA for evaluating differences among 3 study groups was used.  Pearson product-moment correlation was calculated to test associations among variables.  Partial correlation analysis allowed us to evaluate the association among indirect calorimetry variables and anthropometric and metabolic parameters after controlling for BMI and total volume of expired air.  Multivariate linear regression analyses were used to test the independent association of age, BMI, waist to hip ratio, FFM, plasma glucose levels, and total volume of expired air with RMR and RQ.

Data Collection Summary:

Timing of Measurements

Subjects underwent a standard diet based on WHO recommendations for a 2-week period before the calorimeter evaluation.  At the end of 2 weeks, fasting blood samples were collected the day before the calorimeter evaluation.

Dependent Variables

  • Fasting blood samples analyzed for glucose, total cholesterol, triglycerides, free fatty acids, total protein, albumin, blood cell counts through routine methods 
  • Weight, height, BMI
  • Waist and hip circumferences
  • Body density and body fat measured through skinfold thickness measurements
  • Mini Mental State Examination used to assess cognitive function
  • RMR assessed through indirect calorimetry using standard protocol

Independent Variables

  • Age

Control Variables

  • BMI
  • Total volulme of expired air
Description of Actual Data Sample:

Initial N: 28 long-lived females, 26 adult females, 27 younger elderly females

Attrition (final N):  81 subjects as above

Age:  long-lived subjects were >95 years old, adults were < 65 years old, aged subjects were aged 66 - 94 years

Ethnicity: not mentioned

Other relevant demographics:  see Results


Location:  Italy


Summary of Results:


  Adult subjects P value Aged subjects P value

Long-lived subjects

RF (breaths/min) 18 +/- 2 NS 19 +/- 2 NS 18 +/- 2

Total volume of expired air (liters)

0.471 +/- 0.1

0.001 0.349 +/- 0.07


0.443 +/- 0.09

VO2 (ml/min) 232.2 +/- 26.1 0.001 170.5 +/- 28.7 0.001 216.2 +/- 28.5
VCO2 (ml/min) 192.1 +/- 20.6 0.001 126.7 +/- 24.5 0.001 172.4 +/- 25.3
RQ 0.82 +/- 0.02 0.001 0.74 +/- 0.04 0.001 0.79 +/- 0.03

RMR (kcal/diet)

1404 +/- 216

0.001 1065 +/- 303


1324 +/- 222

Other Findings

All subjects were not obese or malnourished and had plasma glucose and lipid parameters within laboratory range.

In the whole population, RMR was negatively correlated with age (P < 0.05), waist to hip ratio (P < 0.001), fat mass (P < 0.001), and percent body fat (P < 0.03); RQ displayed an age-related decrease (P < 0.001) and was negatively correlated with waist hip ratio (P < 0.001) and fat free mass (P < 0.006).

In multivariate analysis, both RMR and RQ had FFM, waist to hip ratio, but not BMI as significant and independent determinants.

Splitting the whole study group into subgroups according to age, long-lived subjects had oxygen volume, carbon dioxide volume, and RQ significantly higher than aged subjects but lower than adult subjects.

In addition, long-lived subjects had total volume of expired air and RMR greater than aged subjects but not different from ones found in adults.

In long-lived subjects, RQ was negatively correlated with percent body fat (P < 0.02), plasma glucose (P < 0.05), free fatty acid (P < 0.05) and waist to hip ratio (P < 0.05) whereas RMR was negatively correlated with waist to hip ratio (P < 0.05).

No significant associations of RMR and RQ with FFM were found. 

Author Conclusion:

In conclusion, our data demonstrate that human longevity seems protected toward an age-related decline.  The exact mechanisms of the preservation of the metabolic changes need to be further elucidated by future studies.  It is likely that the lack of the anthropometrics derangement found in long-lived subjects may preserve these individuals from the age-related energy expenditure derangement.  However, because our findings were obtained from cross-sectional data, this hypothetical cause-effect relationship can be emphasized but not definitely proved.  Notwithstanding, it is likely that variants of gene involved in the regulation of energy expenditure and substrate oxidation might help to explain for the unexpected phenotype found in long-lived subjects and justify the potential link between waist to hip ratio and energy metabolism, independently of fat free mass.

Funding Source:
Government: NIH, NIDDK
Reviewer Comments:

Authors acknowledge that the association design is a potential limitation of the study.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) N/A
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? Yes
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes