Research

Commentary

Using the Energy Gap to Address Obesity: A Commentary

How Did the Obesity Pandemic Develop?

The concept of an energy gap emerged subsequent to research to better understand how the high prevalence of obesity might have arisen in the United States. Longitudinal (Coronary Artery Risk Development In Young Adults study) data and cross-sectional (National Health and Nutrition Examination Survey) datasets that covered a period of approximately 8 years were analyzed to determine the distribution of weight gain over time (3). Results showed that most people were gaining weight gradually over

The Concept of the Energy Gap

The term energy gap was coined to estimate the degree of change in the energy balance point (the absolute energy intake and expenditure at which balance is reached) required for success in body weight goals. The two primary strategies that are especially relevant to the energy gap, in concept, are prevention of excessive weight gain and maintenance of weight loss (Figure 3).

The energy gap for weight gain prevention is the amount of change in the energy balance point needed to prevent further

The Energy Gap for Weight-Loss Maintenance

The energy gap for weight-loss maintenance was defined as the amount of change in the energy balance point needed to maintain a specific amount of weight loss (16). Because energy requirements decrease proportionally with a decrease in body mass, energy requirements are lower after weight loss. The energy gap for weight-loss maintenance is a tool that provides an estimate of how energy requirements change with weight loss, which in turn provides an estimate of how energy balance must be changed

Using the Energy Gap to Guide Strategies to Address Obesity

The energy gap for weight-loss maintenance can be a useful tool to help with obesity treatment. A great deal of effort is devoted to developing better interventions to treat obesity. With the exception of bariatric surgery, there has not been a great deal of success in helping people maintain substantial weight losses. Many people can achieve significant weight losses with our current interventions, but very little of this weight loss seems to be maintained by most people over the long-term (23

Large vs Small Behavior Changes to Address Obesity

Figure 5 shows estimates of the energy gaps for prevention of weight gain and for maintenance of 10% and 15% weight loss. Obviously, it would be desirable to produce and maintain large changes in diet and physical activity to treat existing obesity, and better ways to accomplish this should be investigated. In addition, what is achievable with current efforts to sustain behavior change should be further explored. Not all efforts should be devoted to obesity treatment when it may be possible,

Small Behavior Changes

The relatively small energy gap for preventing weight gain suggests that substantial success in addressing obesity could be achieved with small behavioral changes, but effective approaches to produce and sustain these changes are still needed. Accumulating evidence suggests that small behavior changes, on the order of 100 kcal/day or fewer, can be achieved and sustained by many people. For example, Bravata and colleagues reviewed studies using pedometers to increase physical activity (25).

What Would it Take to Improve Obesity Treatment?

If it were true that, with the exception of bariatric surgery, current strategies are not sufficient to produce and sustain the changes in energy balance required to restore normal weight in the population, it would be important to ask what it would take to improve obesity treatment. Obesity has been described as a mismatch between human physiology and the environment in which we live (31). Better treatment of obesity may require modifying human physiology, modifying the environment in which we

Should We Focus on Changing Food Intake or Physical Activity?

Unfortunately, there is still some debate about whether modifying food intake or physical activity is more critical for addressing obesity. Swinburn and colleagues recently suggested that the obesity epidemic in the US population can be explained entirely by increases in food intake (14). This analysis fails to appreciate that much of the increase in food intake in the population may be subsequent to weight gain, which, in turn, may be subsequent to reductions in physical activity that have

Summary

The global obesity pandemic has arisen from small imbalances in energy intake and expenditure that have accumulated over time. For primary obesity prevention, the energy gap in the United States is less than 100 kcal/day for 90% of the population, meaning that relatively small changes in energy intake and expenditure adding up to 100 kcal/day could arrest excess weight gain in most people. Preventing further weight gain in the population could substantially reduce the prevalence of obesity