Energy expenditure of young men from obese and non-obese families.

Sixteen young non-obese men, seven of whom had an obese parent, were studied under standardized conditions in a respiration chamber to assess their metabolic rate during sleep, at rest, in response to food and during a variety of exercises. The men from obese families were already fatter than the 'normal' group from non-obese families but reported equivalent intakes of energy, had a normal pattern of energy expenditure and could not be distinguished as a group from the men of normal-weight parents. Only the three men of lighter weight of obese parents had a lower energy expenditure per kg fat-free mass and a lower thermic response to food than the normal group; those who were already overweight did not differ from the normal group in their energy expenditure.