Because most obese persons are inactive, physical activity interventions in this group should be approached with low starting levels and slow progression to higher levels of activity. The ideal level of physical activity for a person is not known, but as a general rule, some activity is better than none at all and more is better than less. Therefore, we recommend that a gradual reshaping of a participant's physical activity pattern over time be the focus of intervention, rather than providing a strict, regimented, and specific dose of activity in an exercise prescription.
The most feasible mode of activity for most adults is walking. It can be done anywhere and requires no equipment other than a pair of comfortable shoes, and the intensity is not aversive for most obese persons. It is tempting to recommend a specific amount of activity for obese individuals, but we believe that it is better not to give a universal target for all. Each person should develop a realistic goal for increasing activity, perhaps with professional guidance, which can be modified over time as activity levels increase. It is reasonable to suggest a gradual progression up to 1 hour of moderate-intensity activity (such as brisk walking) each day (Bouchard et al., 1993). It is important to stress that this amount of activity does not need to be obtained in a single session, but can be accumulated over the course of a day. Those who cannot achieve this level of physical activity should remember that some activity is better than none at all. As participants become more physically fit, they will be capable of more activity; they may ultimately engage in more vigorous activities such as cycling, jogging, or other vigorous sports or recreational activities and thereby achieve their caloric-expenditure goals in a shorter period of time. Selection of activity goals and the type of activities to be used are highly individualized matters. Persons should be encouraged to find what works for them and should evaluate different approaches until a sustainable activity plan is developed.
Generally, the more restrictive the diet, the greater are the risks of adverse effects associated with weight loss. Do-it-yourself and nonclinical programs must be safe for their clients. Clinical programs must also be as safe as reasonably possible, given that they are likely to be treating the very obese with comorbidities and health problems. Programs must insist that clients with one or more obesity-related comorbidities be monitored. A client should expect a program to provide detailed information about any potential risks that could occur. Special attention must be paid to the safety of programs for children, pregnant women, and the elderly. In general, no children or adolescents should be placed on a weight-management program without first consulting their pediatrician or family