TY - JOUR

T1 - Relationship between body fat mass and free fatty acid kinetics in men and women

AU - Mittendorfer, Bettina

AU - Magkos, Faidon

AU - Fabbrini, Elisa

AU - Mohammed, B Selma

AU - Klein, Samuel

N1 - (Ekstern)

PY - 2009

Y1 - 2009

N2 - An increased release of free fatty acids (FFAs) into plasma likely contributes to the metabolic complications associated with obesity. However, the relationship between body fat and FFA metabolism is unclear because of conflicting results from different studies. The goal of our study was to determine the inter-relationships between body fat, sex, and plasma FFA kinetics. We determined FFA rate of appearance (Ra) in plasma, by using stable isotopically labeled tracer techniques, during basal conditions in 106 lean, overweight, and obese, nondiabetic subjects (43 men and 63 women who had 7.0-56.0% body fat). Correlation analyses demonstrated: (i) no differences between men and women in the relationship between fat mass (FM) and total FFA Ra (micromol/min); (ii) total FFA Ra increased linearly with increasing FM (r = 0.652, P < 0.001); (iii) FFA Ra per kg FM decreased in a curvilinear fashion with increasing FM (r = -0.806; P < 0.001); (iv) FFA Ra in relationship to fat-free mass (FFM) was greater in obese than lean subjects and greater in women than in men; and (v) abdominal fat itself was not an important determinant of total FFA Ra. We conclude that total body fat, not regional fat distribution or sex, is an important modulator of the rate of FFA release into plasma. Although increased adiposity is associated with a decrease in fatty acid release in relationship to FM, this downregulation is unable to completely compensate for the increase in FM, so total FFA Ra and FFA Ra with respect to FFM are greater in women than in men and in obese than in lean subjects.

AB - An increased release of free fatty acids (FFAs) into plasma likely contributes to the metabolic complications associated with obesity. However, the relationship between body fat and FFA metabolism is unclear because of conflicting results from different studies. The goal of our study was to determine the inter-relationships between body fat, sex, and plasma FFA kinetics. We determined FFA rate of appearance (Ra) in plasma, by using stable isotopically labeled tracer techniques, during basal conditions in 106 lean, overweight, and obese, nondiabetic subjects (43 men and 63 women who had 7.0-56.0% body fat). Correlation analyses demonstrated: (i) no differences between men and women in the relationship between fat mass (FM) and total FFA Ra (micromol/min); (ii) total FFA Ra increased linearly with increasing FM (r = 0.652, P < 0.001); (iii) FFA Ra per kg FM decreased in a curvilinear fashion with increasing FM (r = -0.806; P < 0.001); (iv) FFA Ra in relationship to fat-free mass (FFM) was greater in obese than lean subjects and greater in women than in men; and (v) abdominal fat itself was not an important determinant of total FFA Ra. We conclude that total body fat, not regional fat distribution or sex, is an important modulator of the rate of FFA release into plasma. Although increased adiposity is associated with a decrease in fatty acid release in relationship to FM, this downregulation is unable to completely compensate for the increase in FM, so total FFA Ra and FFA Ra with respect to FFM are greater in women than in men and in obese than in lean subjects.

KW - Absorptiometry, Photon

KW - Adipose Tissue/metabolism

KW - Adolescent

KW - Adult

KW - Blood Glucose/metabolism

KW - Fatty Acids, Nonesterified/blood

KW - Female

KW - Humans

KW - Insulin/blood

KW - Kinetics

KW - Male

KW - Middle Aged

KW - Obesity/blood

KW - Regression Analysis

KW - Young Adult

U2 - 10.1038/oby.2009.224

DO - 10.1038/oby.2009.224

M3 - Journal article

C2 - 19629053

VL - 17

SP - 1872

EP - 1877

JO - Obesity

JF - Obesity

SN - 1930-7381

IS - 10

ER -