Impact of a moderately energy-restricted diet on energy metabolism and body composition in non-obese men.
OBJECTIVE
Since little information is available on the capacity of the non-obese to adapt to a moderate decrease in energy intake, the effect of a 10-week moderately energy-restricted diet (ER) on energy expenditure and body composition was studied.


METHODS
A controlled intervention study. After a weight-maintaining run-in period of 2 weeks, the ER group received a diet that contained 9.2 MJ/day on average, i.e. 80% of the energy of their habitual diet (estimated by means of a 7-day dietary record) for the next ten weeks while the control group received the weight-maintaining diet.


METHODS
Subjects continued daily life habits and came to the Institute every evening to have dinner and to receive food for the next 24 h.


METHODS
24 healthy non-obese, middle-aged men participated. Subjects were matched for age and body mass index and randomly assigned to a control group (n = 8) or an ER group (n = 16).


RESULTS
Average daily metabolic rate (ADMR, i.e. total energy expenditure), measured with doubly labeled water in eight subjects of the ER group, appeared to be 82.5% of reported energy intake resulting in an actual level of energy restriction in these eight subjects of 33% on average (range 18-42%), rather than 20%. Subjects in the ER group lost 7.4 +/- 1.7 kg; 83% of this weight loss was fat mass, 17% was fat-free mass. Subjects in the control group lost some weight too (2.1 +/- 1.5 kg). Resting metabolic rate (RMR) (MJ/day) decreased in the ER group (P < 0.001). In this group the thyroid hormone triiodothyronine (T3) decreased (P < 0.001), while reverse T3 (rT3) increased (P < 0.05). ADMR decreased significantly.


CONCLUSIONS
Under conditions of a controlled moderately energy-restricted diet in daily life a significant weight loss can be induced, similar to that observed after a balanced dietary deficit, providing 5 MJ/day. In addition, moderate energy restriction induces a decrease in fat-free mass and a fall in RMR.
Velthuis-te Wierik
E J
EJ
TNO Nutrition and Food Research Institute, Department of Physiology and Kinetics, Zeist, Netherlands.
Westerterp
K R
KR
van den Berg
H
H
D000328:Adult; D001823:Body Composition / Q000502:physiology*; D003404:Creatinine / Q000652:urine; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015431:Weight Loss / Q000502:physiology
D014284:Triiodothyronine; D003404:Creatinine; D013974:Thyroxine