Research

The American College of Sports Medicine (ACSM) recently published its current Position Stand on “Appropriate Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults” (Jakicic, J.M., et al., 2001, Medicine & Science in Sports & Exercise, 33 [12], 2145-56). This evidence-based position paper updates existing guidelines, including those pertaining to the quality and quantity of exercise necessary for weight loss. For fitness professionals wishing a short but well-referenced document that includes information on the role of exercise intensity, intermittent exercise, resistance exercise and lifestyle activity, this paper provides an excellent and concise resource. The following excerpts from the Position Stand give an overview of the document, clarification regarding exercise duration and weight loss, and the final recommendations.

Overview of the Position Stand

In excess of 55 percent of adults in the United States are classified as either overweight (body mass index [BMI] = 25-29.9 kg/m²) or obese (BMI ≥ 30 kg/m²).To address this significant public health problem, ACSM recommends that the combination of reductions in energy intake and increases in energy expenditure, through structured exercise and other forms of physical activity, be a component of weight loss intervention programs. An energy deficit of 500 to 1,000 kilocalories (kcal) per day achieved through reductions in total energy intake is recommended. Moreover, it appears that reducing dietary fat intake to < 30 percent of total energy intake may facilitate weight loss by reducing total energy intake. Although there may be advantages to modifying protein and carbohydrate intake, the optimal doses of these macronutrients for weight loss have not been determined. Significant health benefits can be recognized with participation in a minimum of 150 minutes (2.5 hours) of moderate-intensity exercise per week, and overweight and obese adults should progressively increase to this initial exercise goal. However, there may be advantages to progressively increasing exercise to 200 to 300 minutes (3.3-5 hours) of exercise per week, as recent scientific evidence indicates that this level of exercise facilitates the long-term maintenance of weight loss. The addition of resistance exercise to a weight loss intervention will increase strength and function but may not attenuate the loss of fat-free mass typically observed with reductions in total energy intake and loss of body weight. When medically indicated, pharmacotherapy [drug therapy] may be used for weight loss, but pharmacotherapy appears to be most effective when used in combination with modifications of both eating and exercise behaviors. ACSM recommends that the strategies outlined in this position paper be incorporated into interventions targeting weight loss and the prevention of weight regain for adults.

Exercise Duration and Weight Loss

The current public health recommendation for physical activity is for individuals to participate in at least 30 minutes of moderate-intensity physical activity on most, preferably all, days of the week. This recommendation has typically been interpreted as a minimum of 150 minutes of physical activity per week (5 days/week, 30 minutes/day) and is based primarily on the effects of exercise on cardiovascular disease and other chronic conditions such as diabetes mellitus. However, close examination of the scientific evidence suggests that levels of exercise greater than this minimum recommended amount may be important for maintaining weight loss long term. . . .

The [research-based] recommendation to progress overweight adults to 200 to 300 minutes of exercise per week or > 2000 kilocaries per week may present a significant challenge for interventionists and public health professionals. Therefore, this recommendation should be viewed in the context of the exercise level that most individuals are willing to adopt and maintain. In response to this concern, it is recommended that individuals be progressed to these higher levels of exercise gradually over time and that a variety of behavioral strategies be used to facilitate the adoption of this level of exercise. However, even in the absence of weight loss and attainment of these higher levels of exercise, overweight individuals can realize significant improvements in health by achieving the minimum public health recommendation for physical activity and by improving their level of cardiorespiratory fitness.

Summary of ACSM Recommendations for
Weight Loss Treatment

Based on the evidence presented in this Position Stand, ACSM recommends that individuals seeking weight loss treatment and prevention of weight regain select programs that meet the following guidelines:

1. It is recommended that individuals with a BMI > 25 kg/m² consider reducing their body weight, especially if this level of body weight is accompanied by an increase in abdominal adiposity. Individuals with a BMI ≥ 30 kg/m² are encouraged to seek weight loss treatment. Although it is recognized that BMI may misclassify the health risk of very active and/or lean individuals, the use of BMI provides a meaningful clinical assessment of health risk. Moreover, although it is also recognized that more sophisticated measures of body composition are available, there is no consensus on the absolute amount of body fatness at which health risk increases.

2. It is recommended that overweight and obese individuals target reducing their body weight by a minimum of 5 to 10 percent and maintain at least this magnitude of weight loss long term. This amount of weight loss is consistent with what is attainable with standard weight loss programs that focus on modifying eating and exercise behaviors, and this amount of weight loss has been shown to be associated with improvements in risk factors and a reduced likelihood of chronic diseases, including coronary heart disease, type 2 diabetes, hypertension and hyperlipidemia.

3. It is recommended that individuals strive for long-term weight maintenance and the prevention of weight regain over the long term, especially when weight loss is not desired or when attainment of ideal body weight is not achievable. Prevention of weight gain or weight regain has been defined as maintaining a body weight that is within 2.3 kg (5 pounds) of one’s current weight.

4. It is recommended that weight loss programs target changing both eating and exercise behaviors, as sustained changes in both behaviors have been shown to result in significant long-term weight loss. Moreover, it is important for programs targeting modifications in these behaviors to incorporate strong behavioral modification strategies to facilitate the adoption and maintenance of the desired changes in behavior.

5. It is recommended that overweight and obese individuals reduce their current level of energy intake by 500 to 1,000 kcal per day to achieve weight loss and that this be combined with a reduction in dietary fat to < 30 percent of total energy intake. It is also recommended that an individualized level of energy intake be established that prevents weight regain after initial weight loss, while maintaining a low-fat diet (≤ 30% of total energy intake). Additional research is needed with regard to changes in other macronutrients and long-term weight loss.

6. It is recommended that overweight and obese individuals progressively increase to a minimum of 150 minutes of moderate-intensity physical activity per week, as this level of exercise may have a positive impact on health in overweight and obese adults. However, for long-term weight loss, overweight and obese adults should eventually progress to higher amounts of exercise (e.g., 200-300 minutes/week or ≥ 2000 kcal/week of leisure-time physical activity).

7. It is recommended that resistance exercise supplement the endurance exercise program in overweight and obese adults who are undertaking modest reductions in energy intake to lose weight. Resistance exercise should focus on improving muscular strength and endurance in this population.

8. It is recommended that pharmacotherapy for weight loss only be used in individuals with a BMI ≥ 30 kg/m², or with a BMI > 27 kg/m² in the presence of additional comorbidities. In addition, it is recommended that weight loss medications only be used in combination with a strong behavioral intervention that focuses on modifying eating and exercise behaviors, and be used under the supervision of a physician.