Prolonged adaptation to fat-rich diet and training; effects on body fat stores and insulin resistance in man.
OBJECTIVE
To investigate the effect of prolonged adaptation to training and fat- or carbohydrate-rich diet on body composition and insulin resistance.


METHODS
Longitudinal study. Of three groups two consumed a fat-rich diet, of which one performed regular training (FAT-Train, n=17) and the other maintained normal habitual activity (Fat-Control, n=8). The third group trained and consumed a carbohydrate-rich diet (CHO-Train, n=16).


METHODS
Forty-one untrained, healthy male subjects.


METHODS
Before and after 7 weeks body composition was estimated from skinfold measurements. At rest the respiratory exchange ratio (RER) was determined by the Douglas bag technique. Glycogen was determined in m vastus lateralis and concentrations of insulin and triacylglycerol in serum and glucose, fatty acid and beta-hydroxy-butyrate in plasma was measured. The insulin resistance index was calculated from fasting plasma insulin and glucose values.


RESULTS
Across the 7 weeks body weight was reduced (1.3+/-0.3%) in all three groups, however body fat mass was decreased only in the CHO-Train (13%) and maintained in the two FAT-groups. RER at rest was similarly decreased (5%) in the three groups. Plasma insulin tended to decrease (16%) in CHO-Train (P=0.065) and remained unchanged in the two FAT-groups. In contrast plasma glucose (4.6+/-0.1 mmol/l) and plasma FA (453+/-27 micromol/l) remained unchanged across the 7 weeks. The calculated insulin resistance index HOMA-R(mod) was significantly decreased by 19% in CHO-train but remained unchanged in both of the FAT-groups, whereas the calculated insulin secretion index HOMA-beta(mod) was unchanged in all three groups.


CONCLUSIONS
In the present study we demonstrate that despite of a mild energy deficit body fat mass was maintained after prolonged adaptation to fat-rich diet both when normal physical activity was maintained and when training was performed. In contrast a significant decrease in fat mass was observed when carbohydrate-rich diet and training was combined. Furthermore we observed that the insulin resistance index was significantly decreased only when training was combined with a carbohydrate-rich diet.
Copenhagen Muscle Research Centre, Copenhagen, Denmark. jhelge@cmrc.dk
J W
JW
Helge
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000222:Adaptation, Physiological; D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D000886:Anthropometry; D001786:Blood Glucose; D001823:Body Composition; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D015444:Exercise; D005227:Fatty Acids / Q000097:blood; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008137:Longitudinal Studies; D008297:Male; D012016:Reference Values; D012129:Respiratory Function Tests; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D007328:Insulin; D014280:Triglycerides; D006003:Glycogen; D020155:3-Hydroxybutyric Acid