Most investigators agree that the process of weight reduction on a hypocaloric diet is associated with a decline in resting-energy expenditure. Whether the reduction in weight loss associated with decreasing resting-energy expenditure can be blunted by exercise is open to debate. Inconsistent findings may relate to methodologic differences. The effects of exercise on skeletal muscle metabolism may be very different 3 or 4 days after exercise from the effects 1 day after exercise.
Some studies fail to specify when, relative to the last exercise period, subjects are studied.
Some studies report that women undergoing aerobic training during hypocaloric feeding experienced a significantly smaller decline in resting-energy expenditure than women undergoing resistance training. Other studies reported a greater blunting of the decline in resting-energy expenditure in adults treated with diet and resistance training compared with aerobic training. Still others have not found that the exercise training modality makes a difference in terms of resting-energy expenditure rate. All in all, research in this area favors the view that the addition of exercise to a weight loss regimen will preserve lean body mass and relieve at least some of the probable decline in resting metabolic rate during weight loss. These can be added to the list of beneficial effects of regular exercise on insulin resistance, hyperlipidemia, and other morbid conditions associated with obesity.