Long-term effects of a high-protein, low-carbohydrate diet on weight control and cardiovascular risk markers in obese hyperinsulinemic subjects

G. D. Brinkworth, M. Noakes, J. B. Keogh, N. D. Luscombe, G. A. Wittert, P. M. Clifton

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OBJECTIVE: To compare the long-term compliance and effects of two low-fat diets differing in carbohydrate to protein ratio on body composition and biomarkers of cardiovascular disease risk in obese subjects with hyperinsulinemia. DESIGN: Outpatient, parallel, clinical intervention study of two groups of subjects randomly assigned to either a standard protein (SP; 15% protein, 55% carbohydrate) or high-protein (HP; 30% protein, 40% carbohydrate) diet, during 12 weeks of energy restriction (∼6.5 MJ/day) and 4 weeks of energy balance (∼8.3 MJ/day). Subsequently, subjects were asked to maintain the same dietary pattern for the succeeding 52 weeks with minimal professional support. SUBJECTS: A total of 58 obese, nondietetic subjects with hyperinsulinemia (13 males/45 females, mean age 50.2 y, mean body mass index (BMI) 34.0 kg/m2, mean fasting insulin 17.8 mU/l) participated in the study. MEASUREMENTS: Body composition, blood pressure, blood lipids, fasting glucose, insulin, CRP and sICAM-1 were measured at baseline and at weeks 16 and 68. Urinary urea/creatinine ratio was measured at baseline, week 16 and at 3 monthly intervals thereafter. RESULTS: In total, 43 subjects completed the study with similar dropouts in each group (P = 0.76). At week 68, there was net weight loss (SP -2.9 ± 3.6%, HP -4.1 ± 5.8%; P < 0.01) due entirely to fat loss (P < 0.001) with no diet effect. Both diets significantly increased HDL cholesterol concentrations (P < 0.001) and decreased fasting insulin, insulin resistance, sICAM-1 and CRP levels (P < 0.05). Protein intake was significantly greater in HP during the initial 16 weeks (P < 0.001), but decreased in HP and increased in SP during 52-week follow-up, with no difference between groups at week 68, indicating poor long-term dietary adherence behaviour to both dietary patterns. CONCLUSION: Without active ongoing dietary advice, adherence to dietary intervention is poor. Nonetheless, both dietary patterns achieved net weight loss and improvements in cardiovascular risk factors.

Original languageEnglish
Pages (from-to)661-670
Number of pages10
JournalInternational Journal of Obesity
Issue number5
Publication statusPublished - 1 May 2004


  • C-reactive protein
  • Diet composition
  • Dual X-ray absorptiometry
  • Insulin sensitivity
  • Lipids
  • Soluble intracellular adhesion molecule-1
  • Weight loss

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

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