Effect of a high-protein, energy-restricted diet on weight loss and energy expenditure after weight stabilization in hyperinsulinemic subjects

doi:doi:10.1038/sj.ijo.0802270

International Journal of Obesity homepage

International Journal of Obesity (2003) 27, 582–590. doi:10.1038/sj.ijo.0802270

Effect of a high-protein, energy-restricted diet on weight loss and energy expenditure after weight stabilization in hyperinsulinemic subjects

N D Luscombe¹, P M Clifton², M Noakes², E Farnsworth² and G Wittert³

¹Department of Physiology, University of Adelaide, South Australia
²CSIRO Health Science and Nutrition, Adelaide, South Australia
³Department of Medicine, University of Adelaide, South Australia

Correspondence: Dr G Wittert, Department of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, SA 5000, Australia. E-mail: gwittert@medicine.adelaide.edu.au

Received 21 February 2002; Revised 22 July 2002; Accepted 27 September 2002.

Top

Abstract

OBJECTIVE: To determine the effect of replacing some dietary carbohydrate with protein, during energy restriction, on weight loss, total energy expenditure (TEE), resting energy expenditure (REE), respiratory quotient (RQ), and the thermic effect of feeding (TEF) in subjects with hyperinsulinemia.

DESIGN: Parallel, clinical intervention study of 12 weeks energy restriction (6.5 MJ/day) and 4 weeks energy balance (8.2 MJ/day) in two groups of subjects randomly assigned to either a high-protein (HP) diet (27% of energy (%E) as protein, 45%E as carbohydrate) or a lower-protein (LP) diet (16%E as protein, 57%E as carbohydrate).

SUBJECTS: A total of 36 obese nondiabetic volunteers with hyperinsulinemia (10 males/26 females, aged 34–65 y, BMI 28–43 kg/m², fasting insulin 12–45 mU/l).

MEASUREMENTS: Body weight and composition, TEE, REE, and RQ were measured at baseline and at week 16. In addition, the TEF to an HP or LP meal was determined for 3 h, at baseline and at week 16.

RESULTS: After 16 weeks, weight loss was similar in response to each diet; the overall decrease was 7.9 plusminus 0.6 kg (P<0.001), of which 6.80.5 kg was fat (P<0.001). REE fell similarly with each diet; the overall decrease was 719106 kJ/day (P<0.001). The TEF was 2% greater after the HP than after the LP meal at baseline (P<0.01) and 0.8% greater at week 16 (P=0.35). After 16 weeks, the TEF was not reduced in either dietary group. There was no change in TEE after 16 weeks.

CONCLUSION: In subjects with hyperinsulinemia an energy-restrictive diet containing an increased protein-to-carbohydrate ratio does not enhance weight loss or significantly affect energy expenditure. Caloric restriction, rather than the macronutrient composition of the diet, is the most important determinant of weight loss.