Impaired fat-induced thermogenesis in obese subjects: the NUGENOB study.
OBJECTIVE
To study energy expenditure before and 3 hours after a high-fat load in a large cohort of obese subjects (n = 701) and a lean reference group (n = 113).


METHODS
Subjects from seven European countries underwent a 1-day clinical study with a liquid test meal challenge containing 95% fat (energy content was 50% of estimated resting energy expenditure). Fasting and 3-hour postprandial energy expenditures, as well as metabolites and hormones, were determined.


RESULTS
Obese subjects had a reduced postprandial energy expenditure after the high-fat load, independent of body composition, age, sex, research center, and resting energy expenditure, whereas within the obese group, thermogenesis increased again with increasing BMI category. Additionally, insulin resistance, habitual physical activity, postprandial plasma triacylglycerols, and insulin were all independently positively related to the postprandial energy expenditure. Resting energy expenditure, adjusted for fat-free mass, increased with degree of obesity, a difference that disappeared after adjustment for fat mass. Furthermore, insulin resistance, fasting plasma free fatty acids, and cortisol were positively associated, whereas fasting plasma leptin and insulin-like growth factor-1 were negatively associated, with resting energy expenditure.


CONCLUSIONS
The 3-hour fat-induced thermogenic response is reduced in obesity. It remains to be determined whether this blunted thermogenic response is a contributory factor or an adaptive response to the obese state.
Blaak
Ellen E
EE
Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht, The Netherlands. E.Blaak@HB.Unimaas.nl
Hul
Gabby
G
Verdich
Camilla
C
Stich
Vladimir
V
Martinez
J Alfredo
JA
Petersen
Martin
M
Feskens
Edith F M
EF
Patel
Kishor
K
Oppert
Jean Michel
JM
Barbe
Pierre
P
Toubro
Søren
S
Polak
Jan
J
Anderson
Ingalena
I
Astrup
Arne
A
Macdonald
Ian
I
Langin
Dominique
D
Sørensen
Thorkild
T
Saris
Wim H
WH
D017667:Adipocytes / Q000502:physiology*; D000328:Adult; D001481:Basal Metabolism / Q000502:physiology; D015992:Body Mass Index; D004734:Energy Metabolism / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D019518:Postprandial Period; D022722:Thermogenesis / Q000502:physiology*; D014280:Triglycerides / Q000097:blood
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides; D006854:Hydrocortisone