The term “energy gap” was developed to estimate the change in energy intake (calories) with energy expenditure (physical activity) required to receive a change in body weight. Dietitians and other health professionals use this model to point out that reducing calories below what is neededor increasing daily exercise to burn excess caloriescan result in weight loss. But what previous studies has failed to identify is how much of an energy gap is actually needed to either prevent weight gainor produce a weight loss.
Dr. James Hilla professor of pediatrics and medicine and director for the Center for Human Nutrition at the University of Colorado-Denverwrites a commentary on the energy gap as a feature in the November issue of the Journal of the American Dietetic Association.
After studying data from large studies such as the Coronary Artery Risk Development in Young Adults and the national Helath and Nutrition Examination StudyDr. Hill found that most people gain weight gradually over timewith the average American adult gaining about 1 to 2 pounds each year. It is estimated that this gain comes from eating an excess of about 100 calories over the body’s needs each day.
So prevention of weight gain should be fairly simple – find the calorie level for your personal needs that keeps weight stable. You will likely find that small changes to reduce current calorie needs by 100or to increase daily activity in order to burn 100 more calorieswill maintain your current weight over the long-term.
Weight losshoweveris trickier. Because metabolism drops as weight decreasesit takes more calorie deficit to continue losing weight during a diet than it does prevent the weight gain in the first place. Dr. Hill esimates that the needs for an overweight person to lose weight is between 300 and 500 calories less each day from what they are currently consuming.
The key message in the commentary about the use of energy gap is that small changes in diet and exercise can be very effective in preventing weight gain and should be used to promote a healthier lifestyle among Americans to reduce the rising trend of obesity.
Journal Reference: Journal of the American Dietetic AssociationNovember 2009; pg 1848