NSA: Serum Proteins (2009)

Krotkiewski M, Toss L, Björntorp P, Holm G. The effect of a very-low-calorie diet with and without chronic exercise on thyroid and sex hormones, plasma proteins, oxygen uptake, insulin and C peptide concentrations in obese women. Int J Obes. 1981; 5(3): 287-293. PMID: 7024157
Study Design:
Non-randomized trial.
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To compare a very low calorie diet (VLCD) to VLCD plus chronic exercise in obese women to see if the increased energy demands of exercise are associated with augmented protein loss with an undesirable erosion of lean tissue.

Inclusion Criteria:

Details not described.

  • Obese
  • Middle-aged
  • No history of thyroid, hepatic or renal disorders
  • Stable weight (measured 14 days apart before start of study).
Exclusion Criteria:

None described.

Description of Study Protocol:


Nonrandomized trial.


  • Weight stability confirmed by taking measurements 14 days apart before start of study
  • Patients could choose what group they wanted to belong to: VLCD or VLCD plus exercise
  • Both groups received 500kcal per day in the form of a liquid diet (Called the Cambridge diet) for three weeks
  • VLCD plus exercise group exercised three times per week under the leadership of one of the authors. Each session lasted 55 minutes.
  • Training program was standardized for each subject in relation to maximal work capacity (determined by a work test on a bicycle ergometer with continuous ECG recording and measurement of oxygen consumption at rest, during maximal work and four hours after termination of the work test)
  • Gas samples were analyzed with a Micro-Scholander Method before study and at the end of the three weeks.
Data Collection Summary:

Timing of Measurements

Gas samples were analyzed with a Micro-Scholander Method before the study and at the end of the three weeks.

Dependent Variables

  • Fat cell weight and number
  • Blood glucose
  • Plasma insulin
  • C peptide (fasting)
  • C peptide (after oral glucose load)
  • Body weight
  • Body composition
  • Plasma testosterone
  • Thyroid hormones
  • Sex hormone binding globulin (SHBG)
  • Transcortin
  • Plasma proteins

Independent Variables

Exercise three times per week, 55 minutes each session.

Control Variables

Liquid diet (Cambridge diet) consisting of 47.8g protein, 67g carbohydrates, 5.0g fat per day (500kcal total per day).

Description of Actual Data Sample:
  • Initial N: 20 middle-aged women
  • Attrition (final N): 18 middle-aged women
  • Age: "Middle aged" (but not described).



Before (kg) 


After (kg)


Difference (kg)


Body weight

Group 1 (diet)

101.2±6.4 95.0±6.7 6.2±1.7

Group 2 (diet and exercise)

102.9±6.1 96.1±5.8 6.8±2.6
Body fat      

Group 1 (diet)

46.6±4.1 44.0±4.4 2.6±2.0

Group 2 (diet and exercise)

49.2±4.2 47.3±3.6 1.9±2.4
Lean body mass      

Group 1 (diet)

30.9±1.4 28.9±1.5 2.0±1.2

Group 2 (diet and exercise)

30.5±1.4 27.7±1.3 2.8±1.4



Goteborg, Sweden.


Summary of Results:



Week 0

One Week

Two Week

Three Weeks

T3 nmol per L









diet + exercise

2.16±0.15 1.54±0.03** 1.54±0.10** 1.57±0.12**
rT3 nmol per L        


0.30±0.03 0.42±0.04*** 0.41±0.03*** 0.40±0.03***

diet + exercise

0.26±0.01 0.36±0.03*** 0.34±0.03*** 0.34±0.03***
TBG mg per L        


23.5±1.3 24.3±1.5 23.8±1.2 23.1±1.3

diet + exercise

23.5±1.0 23.7±0.8** 23.0±0.9 22.9±1.0
 Prealbumin g per L        


0.29±0.02 0.24±0.01*** 0.21±0.01*** 0.22±0.01***

diet + exercise

0.25±0.01 0.20±0.01*** 0.17±0.02*** 0.20±0.01***
Retinol binding protein mg per L        


86.3±7.2 73.6±7.4*** 62.6±5.6*** 62.7±6.5***

diet + exercise

74.6±4.9 61.7±4.5*** 56.5±4.9*** 63.9±5.5***
Testosterone mmol per L        


2.18±0.31 2.18±0.30 2.42±0.30 2.55±0.35

diet + exercise

1.65±0.21 1.70±0.15 2.27±0.17*** 2.19±0.24
Sex hormones binding globulin (arbitrary units)        


0.46±0.05 0.69±0.07*** 0.90±0.10*** 1.10±0.10***

diet + exercise

0.67±0.07 0.81±0.09*** 1.01±0.07*** 1.10±0.09***

 * P<0.05

** P<0.01


Other Findings

  • Body weight, body fat and body cell mass decreased in both groups but there was no significant difference
  • Glucose tolerance test deteriorated in the diet-only group but did not change in the VLCD plus exercise group
  • Insulin concentration after oral glucose load did not change in either of the two groups
  • The percentage decrease of C peptide fasting values did not differ between the two groups
  • T4 values did not change in either group
  • Thyroid stimulating hormone values (TSH) did not change in either group
  • Thyroxine-binding globulin (TBG) did not change in either group
  • T4/TBG did not change in either group
  • Albumin concentration did not change in either group
  • C peptide values decreased in both groups after the first week, then increased in the second week. During week three, there was a decrease in the exercise group.


Author Conclusion:

VLCD plus exercise did not produce a higher body weight loss, nor a protective effect on lean body mass.

Funding Source:
University/Hospital: Sahlgren's Hospital, University of Goteberg, Goteberg, Sweden
Reviewer Comments:
  • It is noted in the discussion that, even though body weight loss was higher, body fat lower and lean body mass higher in the exercising group, the differences were probably not significant because of the relatively short period of the study and wide variations within each group
  • There was little detail provided about recruitment, group demographics and exercise program. It would have been useful to have more background information about the subjects [i.e., occupation  (if sedentary most of the day vs. someone with a more active job), to get an idea of energy expenditure).
  • No details were described about the statistical analysis or funding source
  • Several of the answers to the reviewer checklist were "unclear" because not enough detail was provided in the paper.
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) ???
  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) Yes
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? ???
2. Was the selection of study subjects/patients free from bias? ???
  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? No
  2.2. Were criteria applied equally to all study groups? ???
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? No
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) No
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) ???
  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? N/A
  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.) N/A
  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? Yes
  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? N/A
  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? ???
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  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? No
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? No
  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? ???
  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? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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)? ???
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  8.6. Was clinical significance as well as statistical significance reported? ???
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? ???