Physical activity and regulation of food intake: current evidence

Objective: The evidence was reviewed on how physical activity could influen ce the regulation of food intake by either adjusting the sensitivity of app etite control mechanisms or by generating an energy deficit that could adju st the drive to eat Design: Interventionist and correlational studies that had a significant influence on the relationship between physical activity a nd food intake were reviewed. Interventionist studies involve a deliberate imposition of physical activity with subsequent monitoring of the eating re sponse. Correlational studies make use of naturally occurring differences i n the levers of physical activity (between and within subjects) with simult aneous assessment of energy expenditure and intake. Subjects: Studies using lean, overweight, and obese men and women were included. Results: Only 19% of interventionist studies report an increase in energy intake after exerc ise; 65% show no change and 16% show a decrease in appetite. Of the correla tional studies, approximately half show no relationship between energy expe nditure and intake. These data indicate a rather loose coupling between ene rgy expenditure and intake. A common sense view is that exercise is futile as a form of weight control because the energy deficit drives a compensator y increase in food intake. However, evidence shows that this is not general ly true. One positive aspect of this is that raising energy expenditure thr ough physical activity (or maintaining an active life style) can cause weig ht loss or prevent weight gain. A negative feature is that when people beco me sedentary after a period of high activity, food intake is not "down-regu lated" to balance a reduced energy expenditure. Conclusion: Evidence sugges ts that a high lever of physical activity can aid weight control either by improving the matching of food intake to energy expenditure (regulation) or by raising expenditure so that it is difficult for people to eat themselve s into a positive energy balance.