The journal *Medicine & Science in Sports & Exercise* (vol. 41, #2)
includes the American College of Sports Medicine’s new revised
guidelines for “Appropriate Physical Activity Intervention Strategies
for Weight Loss and Prevention of Weight Regain for Adults.”  This
updates their previous 2001 ACSM recommendations.

Here are their specific clinical recommendations and ratings of the
level of scientific evidence supporting each recommendation:

[begin excerpt]

*    For prevention of weight gain in most adults, physical activity of 150 to 250 minutes
per week
, with an energy equivalent of 1200 to 2000 kcal/week, will
prevent weight gain of more than 3% (level of evidence, A).

*There is a dose-response effect of physical activity on weight loss, with physical activity of less
than 150 minutes per week resulting in minimal weight loss, physical activity of more
than 150 minutes per week in modest weight loss of approximately 2 to 3
, and physical activity of more than 225 to 420 minutes per week leading to weight
loss of 5 to 7.5 kg (level of evidence, B).

*To maintain weight after weight loss, some studies suggest that physical activity of
approximately 200 to 300 minutes per week
will help minimize weight
regain, although “more is better.” To date, no well-designed,
sufficiently powered, energy-balance studies provide evidence concerning
the amount of physical activity needed to prevent weight regain after weight loss
(level of evidence, B).

*Lifestyle physical activity, which is an ambiguous term that should be better defined
to assess available evidence in the literature, may help counteract the
small energy imbalance ultimately leading to obesity in most adults
(level of evidence, B).

*If diet restriction is modest but not if diet restriction is severe, physical activity
will increase weight loss
(level of evidence, A).

*Resistance training is ineffective for weight loss with or without diet
restriction, according to limited research evidence. However, some
limited data suggest that resistance training enhances gain or
maintenance of lean mass and loss of body fat during energy restriction.
Furthermore, resistance training may also ameliorate risk factors for
chronic disease, such as low high-density lipoprotein cholesterol
levels, high low-density lipoprotein cholesterol levels, insulin
sensitivity, and blood pressure (level of evidence, B).

[end excerpt]

The article notes that the new ACSM Guidelines are consistent with the
U.S. Dephysical activityrtment of Health & Human Services Physical Activity Guidelines
for Americans.

Here’s the abstract: “Overweight and obesity affects more than 66% of
the adult population and is associated with a variety of chronic
diseases. Weight reduction reduces health risks associated with chronic
diseases and is therefore encouraged by major health agencies.
Guidelines of the National Heart, Lung, and Blood Institute (NHLBI)
encourage a 10% reduction in weight, although considerable literature
indicates reduction in health risk with 3% to 5% reduction in weight.
Physical activity (physical activity) is recommended as a component of weight
management for prevention of weight gain, for weight loss, and for
prevention of weight regain after weight loss. In 2001, the American
College of Sports Medicine (ACSM) published a Position Stand that
recommended a minimum of 150 min·wk-1 of moderate-intensity physical activity for
overweight and obese adults to improve health; however, 200-300 min·wk-1
was recommended for long-term weight loss. More recent evidence has
supported this recommendation and has indicated more physical activity may be necessary
to prevent weight regain after weight loss. To this end, we have
reexamined the evidence from 1999 to determine whether there is a level
at which physical activity is effective for prevention of weight gain, for weight loss,
and prevention of weight regain. Evidence supports moderate-intensity physical activity
between 150 and 250 min·wk-1 to be effective to prevent weight gain.
Moderate-intensity physical activity between 150 and 250 min·wk-1 will provide only
modest weight loss. Greater amounts of physical activity (>250 min·wk-1) have been
associated with clinically significant weight loss. Moderate-intensity
physical activity between 150 and 250 min·wk-1 will improve weight loss in studies that
use moderate diet restriction but not severe diet restriction. Cross-
sectional and prospective studies indicate that after weight loss,
weight maintenance is improved with physical activity >250 min·wk-1. However, no
evidence from well-designed randomized controlled trials exists to judge
the effectiveness of physical activity for prevention of weight regain after weight
loss. Resistance training does not enhance weight loss but may increase
fat-free mass and increase loss of fat mass and is associated with
reductions in health risk. Existing evidence indicates that endurance physical activity
or resistance training without weight loss improves health risk. There
is inadequate evidence to determine whether physical activity prevents or attenuates
detrimental changes in chronic disease risk during weight gain.”

The article is online — but requires a subscription — at: