Moderate carbohydrate, moderate protein weight loss diet reduces cardiovascular disease risk compared to high carbohydrate, low protein diet in obese adults: A randomized clinical trial

Abstract

Background: To evaluate the metabolic effects of two weight loss diets differing in macronutrient composition on features of dyslipidemia and post-prandial insulin (INS) response to a meal challenge in overweight/obese individuals.

Methods: This study was a parallel-arm randomized 4 mo weight loss trial. Adults (n = 50, 47 +/- 7 y) matched on BMI (33.6 +/- 0.6 kg/m2, P = 0.79) consumed energy restricted diets (deficit ~500 kcal/d): PRO (1.6 g.kg-1.d-1 protein and < 170 g/d carbohydrate) or CHO (0.8 g.kg-1.d-1 protein and > 220 g/d carbohydrate) for 4 mos. Meal challenges of respective diets were utilized for determination of blood lipids and post-prandial INS and glucose response at the beginning and end of the study.

Results: There was a trend for PRO to lose more weight (-9.1% vs. -7.3%, P = 0.07) with a significant reduction in percent fat mass compared to CHO (-8.7% vs. -5.7%; P = 0.03). PRO also favored reductions in triacylglycerol (-34% vs. -14%; P < 0.05) and increases in HDL-C (+5% vs. -3%; P = 0.05); however, CHO favored reduction in LDL-C (-7% vs. +2.5%; P < 0.05). INS responses to the meal challenge were improved in PRO compared to CHO (P < 0.05) at both 1 hr (-34.3% vs. -1.0%) and 2 hr (-9.2% vs. +46.2%), an effect that remained significant after controlling for weight or fat loss (both P < 0.05).

Conclusion: A weight loss diet with moderate carbohydrate, moderate protein results in more favorable changes in body composition, dyslipidemia, and post-prandial INS response compared to a high carbohydrate, low protein diet suggesting an additional benefit beyond weight management to include augmented risk reduction for metabolic disease.

Figure 1

Change in insulin concentration. Change in insulin concentration, pmol/L, from baseline to 4 mo at fasted (A) 1 hr (B) and 2 hr (C) post-prandial in response to the meal challenge for adults consuming either the PRO (n = 25, gray bar) or CHO (n = 25, white bar) diet. Values are means ± SEM. *Indicates time × diet interaction P < 0.05.

Figure 2

Fasted serum lipid concentrations. Change in fasted serum lipid concentrations, mmol/L, of LDL-C (A), LDL-C/ApoB ratio (B), HDL-C (C), and triacylglyceride (D), from baseline to 4 mo for adults consuming either the PRO (n = 25) or CHO (n = 25) diet. Values are each individual's data point (X) with means (black line bar) within each group. All outcomes had a time × diet interaction P < 0.05 between group means.