Dietary protein and urinary nitrogen in relation to 6-year changes in fat mass and fat-free mass

TY - JOUR

T1 - Dietary protein and urinary nitrogen in relation to 6-year changes in fat mass and fat-free mass

AU - Ankarfeldt, Mikkel Zøllner

AU - Gottliebsen, K

AU - Ängquist, L

AU - Astrup, Arne

AU - Heitmann, B L

AU - Sørensen, Thorkild I.A.

N1 - CURIS 2015 NEXS 023

PY - 2015/1/10

Y1 - 2015/1/10

N2 - Background: In contrast to the physiological expectation, observational studies show that greater protein intake is associated with subsequent body weight (BW) gain. An increase in fat-free mass (FFM) due to the anabolic effects of protein could explain this. Objective: To examine associations between protein intake and subsequent changes in fat mass (FM) and FFM in longitudinal, observational data. Design: A health examination, including measures of FM and FFM by bioelectrical impedance at baseline and follow-up 6 years later, was conducted. Diet history interviews (DHI) were performed, and 24-h urinary nitrogen collection at baseline was done. In total, 330 participants with DHI, of whom 227 had validated and complete 24-h urine collection data, were analyzed. Macronutrient energy substitution models were used. Results: Mean estimated protein intake was 14.6 E% from DHI and 11.3 E% from urinary nitrogen. Estimated from DHI, FM increased 46 g per year, with every 1 E% protein substituted for fat (95% confidence interval (CI)=13, 79; P=0.006), and FFM increased 15 g per year (1, 30; P=0.046). Results were similar in other substitution models. Estimated from urinary nitrogen, FM increased 53 g per year, with 1 E% protein substituted for other macronutrients (24, 81; P<0.0005), and FFM increased 18 g per year (6, 31; P=0.004). Conclusion: Within a habitual range, a greater protein intake was associated with BW gain, mostly in FM. This is in contrast to the expectations based on physiological and clinical trials, and calls for a better understanding of how habitual dietary protein influences long-term energy balance, versus how greater changes in dietary proteins may influence short-term energy balance.

AB - Background: In contrast to the physiological expectation, observational studies show that greater protein intake is associated with subsequent body weight (BW) gain. An increase in fat-free mass (FFM) due to the anabolic effects of protein could explain this. Objective: To examine associations between protein intake and subsequent changes in fat mass (FM) and FFM in longitudinal, observational data. Design: A health examination, including measures of FM and FFM by bioelectrical impedance at baseline and follow-up 6 years later, was conducted. Diet history interviews (DHI) were performed, and 24-h urinary nitrogen collection at baseline was done. In total, 330 participants with DHI, of whom 227 had validated and complete 24-h urine collection data, were analyzed. Macronutrient energy substitution models were used. Results: Mean estimated protein intake was 14.6 E% from DHI and 11.3 E% from urinary nitrogen. Estimated from DHI, FM increased 46 g per year, with every 1 E% protein substituted for fat (95% confidence interval (CI)=13, 79; P=0.006), and FFM increased 15 g per year (1, 30; P=0.046). Results were similar in other substitution models. Estimated from urinary nitrogen, FM increased 53 g per year, with 1 E% protein substituted for other macronutrients (24, 81; P<0.0005), and FFM increased 18 g per year (6, 31; P=0.004). Conclusion: Within a habitual range, a greater protein intake was associated with BW gain, mostly in FM. This is in contrast to the expectations based on physiological and clinical trials, and calls for a better understanding of how habitual dietary protein influences long-term energy balance, versus how greater changes in dietary proteins may influence short-term energy balance.

U2 - 10.1038/ijo.2014.80

DO - 10.1038/ijo.2014.80

M3 - Journal article

C2 - 24840082

SN - 0307-0565

VL - 39

SP - 162

EP - 168

JO - International Journal of Obesity

JF - International Journal of Obesity

IS - 1

ER -