I found this article here: http://www.soulcysters.net/exercise-weight-loss-how-much-enough-you-wont-like-answer-36210/?highlight=lifestyle
__________________________________________________ __
Physical Activity Recommendations: How Much is Enough?
Substantial data now show that that a high level of physical activity, maybe as much as
80 minutes/day, is required to maintain a substantial reduction in body weight. This is more than twice the current recommendation for physical activity, according to Holly Wyatt, MD. Dr. Wyatt reviewed the recent available data on the amounts of physical activity needed to prevent weight re-gain following weight loss and discussed the critical need for data about how much physical activity prevents weight gain.
Over 60% of American adults are overweight or obese, according to recent studies. Over 54 million Americans are currently dieting, but the national obesity rate continues to rise. Alarmingly, only about 20% of individuals who do lose weight are able to keep it off long-term.
Weight management is also a critical component in the successful management of individuals with diabetes, especially those with type 2 diabetes.
What physical activity recommendations can clinicians make for overweight or diabetic patients who want to lose weight or prevent weight re-gain? The topic is controversial. Dr. Wyatt presented data suggesting that the current recommendations for daily physical activity fall far short of the levels required in clinical trials to prevent weight re-gain.
Current recommendations may not be high enough
Current recommendations from the US Surgeon General Report and the National Institutes of Health, National Heart, Lung, and Blood Institute recommend 30 minutes of moderate intensity exercise most preferably all days of the week. These recommendations developed to improve cardiovascular health and fitness and not to produce weight loss or prevent weight gain or re-gain.
A common misconception, said Dr. Wyatt, is that 30 minutes/day of physical activity is all that is needed to achieve or maintain a weight loss. People feel that if they walk for 30 minutes a day they should lose weight. It is important to note that the current recommendations were not based on what is necessary for long-term weight management.
To make recommendations on how much physical activity is needed for long-term weight management, keep in mind what you want to achieve. Recommendations for weight loss differ from those for weight re-gain stressed Dr. Wyatt.
Weight loss and physical activity
Physical activity should be a part of any weight loss intervention said Dr. Wyatt. However, physical activity does not contribute to weight loss nearly as much as a dietary intervention that reduces caloric intake. Creating a negative energy balance is imperative for weight loss and this is most easily done by reducing energy intake. It is very difficult to create a large negative energy balance, sufficient to produce substantial weight loss, using physical activity alone (Figure 2). Multiple studies have shown that adding moderate amounts of physical activity to a dietary intervention will result in minimal if any additional weight loss.
Exceptions do exist when physical activity levels are increased to greater than 4 hours a day, but for the average individual activity doesn't seem to add much to increase the amount of weight initially lost. According to Dr. Wyatt, recommendations on the amount of physical activity, therefore, take a back seat to implementing successful dietary restriction in this area. However, the opposite appears true once the real hard part starts- maintaining the loss long-term.
Prevention of weight regain hinges on high amounts of physical activity
According to much of the data available, physical activity plays a critical and pivotal role in the prevention of weight re-gain. It is absolutely crucial to successful prevention of weight-regain and one of the best predictors for long-term success, said Dr. Wyatt.
High rates of physical activity are closely related to long-term successes in prevention of weight re-gain. Several studies have been done in an attempt to quantify the amount of physical activity require to prevent weight re-gain.
The first of these is from Schoeller et al.2 who conclude that roughly 80 minutes of moderate daily activity or 35 minutes of vigorous activity added to a sedentary
lifestyle are necessary to prevent weight re-gain. This is significantly more than the 30 minutes on most days recommended by the Surgeon General.
Another study done by Weisnier et al.3 supports the conclusion of Schoeller et al., that the amount of physical activity needed to prevent weight re-gain was 77 minutes per day, or 2.5 times the current recommendations.
The National Weight Control Registry (NWCR) was founded in 1993 by researchers at the University of Colorado and Brown University to study adults who have lost 30 or more pounds and kept from re-gaining it for at least 1 year.4 Subjects who have kept their weight down for a year or longer report burning an average of 2,682 calories per week, to maintain their weight loss (Figure 3). Dr. Wyatt explained that this is the equivalent of walking about 4 miles per day. Only 9% of registry members do not report using physical activity for weight loss maintenance.
These studies and others point to the fact that reduced individuals may need to target much higher levels of physical activity in the range of 60-80 minutes for long-term weight loss success. 30 minutes just may not be enough (Figure 4).
Physical activity recommendations for preventing weight gain
While some studies have shown a negative association between physical activity levels or changes in physical activity levels and weight gain over time, to date there are no prospective, randomized interventions to test and quantify the minimum amount of physical activity required to prevent the weight gain we are currently seeing in the US population. Theoretically a small increase in physical activity should be sufficient to stop the 1-3 lb/yr weight gain seen in much of the population, however, we have little objective evidence on which to base a specific recommendation.
Conclusion
Substantial data suggest that a high level of physical activity in the range of 60-80 minutes is necessary for long-term maintenance of a weight loss. This is substantially higher than our current physical activity recommendations. The amount of physical activity required for preventing weight regain may be different than what would be necessary to halt the weight gain in those with a healthy body weight. While substantial cross sections data does suggest that increasing physical activity could prevent weight gain in the general population, we lack quantitative prospective data to allow us to identify the minimum amount required to make a specific recommendation. While one recommendation may not fit all, there is little doubt that increasing physical activity should be a high priority in both reversing existing obesity and the prevention of "new" obesity.
References
1. Wing RR, Hill JO. Successful weight loss maintenance. Ann Rev Nutr 2001;21:323-341.
2. Schoeller DA, Shay K, Kushner RF. How much physical activity is needed to minimize weight gain in previously obese women? Am J Clin Nutr 1997;66:551-6.
3. Weinsier RL, Hunter GR, Desmond RA, Byrne NM, Zuckerman PA, Darnell BE. Free-living activity energy expenditure in women who are successful and unsuccessful in maintaining a normal body weight. Am J Clin Nutr 2002;75.
4. Klem ML, Wing RR, McGuire MT, Seagle HM, Hill JO. A descriptive study of individuals successful at long-term maintenance of substantial weight loss. Am J Clin Nutr 1997;66:239-46
Source:
http://diabeteshighlights.org/summar...&ld=2002-06-17 
Similar Threads 
October 31st, 2006, 06:09 AM
PCOS & Exercise 
Linear Mode
