Highlights From the North American Society for the Study of Obesity Annual Meeting: A Physician's View

Raymond A. Plodkowski, MD


December 01, 2003

In This Article

Physical Activity for Weight Loss

The second component of energy balance is output. Unfortunately, society has become more sedentary, and it is often difficult to motivate patients to increase physical activity. Kara Gallagher, PhD, a physical activity expert from the University of Pittsburgh, presented evidence-based strategies to increase physical activity.[21] The current recommendation from the US Centers for Disease Control and Prevention states that all Americans should accumulate at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week. The Institute of Medicine has recommended an even greater amount of moderate intensity exercise -- 60 minutes per day. In the setting of a patient actively trying to lose weight, it has been shown in a 12-month study by Jakicic and colleagues[22] that the percent weight loss increases with increased physical activity.

However, patients often create barriers to weight loss that must be addressed. Overweight and obese patients may perceive that they are too tired to exercise, they lack motivation, they are too lazy, they are too fatigued by exercise, exercise is boring, or exercise is inconvenient. Actual barriers to exercise may include lack of time, lack of effort, lack of support, and lack of self-esteem. Dr. Gallagher proposed several strategies to overcome these barriers. One of the greatest barriers to exercise is lack of time. A possible solution is intermittent activity throughout the day rather than a single period of exercise. From a practical standpoint, it might be easier to integrate three 10-minute periods of exercise into a day rather than one 30-minute block. In a study that determined the minutes of exercise per week in groups who were prescribed a long bout of exercise daily vs multiple small bouts of exercise per day, the short-bout group had greater amounts of exercise over the entire course of the 20-week study.[23] Another strategy to fit exercise into busy schedules is to have home-based rather than supervised exercise at a gym or health club. Although it would seem intuitive that a monitored setting would increase compliance, a study by Perri and colleagues[24] showed that at 12 months, a home-based exercise group reported greater compliance with exercise. Planning and reminders are also important in exercise compliance. Exercise cues can include putting exercise equipment in highly visible or high traffic areas (next to the TV in the family room), exercise calendars, exercise "dates" with family and friends, and reminders on the computer, palm pilot, or cell phone.

A final strategy is to put exercise first. People often report they are too tired at the end of the day or that family responsibilities come up throughout the day that conflict with periods set aside for exercise. One strategy to overcome these obstacles is to make exercise the first activity of the morning. Then the hectic activities of the day will not affect exercise compliance.

It is important to accurately measure energy output so that energy balance can be determined for patients, and recently there have been advances in the quantification of energy output. In the past, tools such as physical activity logs were used. This was cumbersome because amounts of exercise had to be quantified using tables that listed energy output in kcal for various activities. Pedometers were a notable advance because patients could receive daily feedback on their total steps per day. Pedometers (eg, Digi-Walker, Yamax Inc, Tokyo, Japan) are about the size of a pager and can be worn by a patient to determine the number of steps that are taken per day.[25] Although the stride length varies from person to person, approximately 2000 to 2500 steps equals 1 mile. Furthermore, 1 mile walked burns approximately 100 kcal. The usual goal is at least 10,000 steps per day. A new tool that may prove to be superior to pedometers for quantifying physical activity is the accelerometer. The Actiwatch is a uniaxial accelerometer (Cambridge Neurotechnology Ltd, Cambridge, UK).[26] It is a simple and relatively inexpensive device for measuring activity in children and adults. The accelerometer produces a signal as the wearer makes physical movement over 0.05 g of force. This signal is measured 32 times per second and processed to provide the amount and duration of movement. This is a significant advance, because the traditional pedometer only quantifies the amount of movement and not the duration. Data are stored within the Actiwatch in nonvolatile memory (data will not be lost if the battery dies). Later, the data can be downloaded and analyzed. A second single-axis accelerometer, the ActiGraph (MTI Health Services, Fort Walton Beach, Florida), was used in assessing physical activity in the elderly and was shown to have a significant correlation with doubly labeled water technique as the gold standard.[27] The Actical (Mini Mitter Co. Inc., Bend, Oregon), an omnidirectional accelerometer, measures activities in all planes.[28]


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