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Does metabolic compensation explain the majority of less-than-expected weight loss in obese adults during a short-term severe diet and exercise intervention?


Byrne, NM and Wood, RE and Schutz, Y and Hills, AP, Does metabolic compensation explain the majority of less-than-expected weight loss in obese adults during a short-term severe diet and exercise intervention?, International Journal of Obesity, 36, (11) pp. 1472-1478. ISSN 0307-0565 (2012) [Refereed Article]

DOI: doi:10.1038/ijo.2012.109


Objective: We investigated to what extent changes in metabolic rate and composition of weight loss explained the less-than-expected weight loss in obese men and women during a diet-plus-exercise intervention.

Design: In all, 16 obese men and women (41  9 years; body mass index (BMI) 39  6 kg m−2) were investigated in energy balance before, after and twice during a 12-week very-low-energy diet (565650 kcal per day) plus exercise (aerobic plus resistance training) intervention. The relative energy deficit (EDef) from baseline requirements was severe (74%87%). Body composition was measured by deuterium dilution and dual energy X-ray absorptiometry, and resting metabolic rate (RMR) was measured by indirect calorimetry. Fat mass (FM) and fat-free mass (FFM) were converted into energy equivalents using constants 9.45 kcal per g FM and 1.13 kcal per g FFM. Predicted weight loss was calculated from the EDef using the '7700 kcal kg−1 rule'.

RESULTS: Changes in weight (-18.6  5.0 kg), FM (-15.5  4.3 kg) and FFM (-3.1  1.9 kg) did not differ between genders. Measured weight loss was on average 67% of the predicted value, but ranged from 39% to 94%. Relative EDef was correlated with the decrease in RMR (R = 0.70, P < 0.01), and the decrease in RMR correlated with the difference between actual and expected weight loss (R = 0.51, P < 0.01). Changes in metabolic rate explained on average 67% of the less-than-expected weight loss, and variability in the proportion of weight lost as FM accounted for a further 5%. On average, after adjustment for changes in metabolic rate and body composition of weight lost, actual weight loss reached 90% of the predicted values.

CONCLUSION: Although weight loss was 33% lower than predicted at baseline from standard energy equivalents, the majority of this differential was explained by physiological variables. Although lower-than-expected weight loss is often attributed to incomplete adherence to prescribed interventions, the influence of baseline calculation errors and metabolic downregulation should not be discounted.

Item Details

Item Type:Refereed Article
Research Division:Health Sciences
Research Group:Sports science and exercise
Research Field:Exercise physiology
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Public health (excl. specific population health) not elsewhere classified
UTAS Author:Byrne, NM (Professor Nuala Byrne)
UTAS Author:Hills, AP (Professor Andrew Hills)
ID Code:110708
Year Published:2012
Web of Science® Times Cited:31
Deposited By:Health Sciences
Deposited On:2016-08-10
Last Modified:2017-12-15

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