Leisure-time physical activity (LTPA) has been closely related to health improvement. The under-appreciation for energy output by nutritionists stems in part from limited data expressed in caloric equivalent. We converted the frequency, duration, and intensity of LTPA, reported from 15,390 adults in the Taiwan National Health Interview Survey 2001, into kilocalories (kcal). Half of Taiwanese adults admit to no LTPA. Women, lower education or income, younger age, smokers and chewers of betel quid; exercised significantly less than their counterparts. Less than 1/5 (18.9%) of the population in Taiwan was physically active at >or=750 kcal/week, and only 1/7 (13.9%) reached a more desirable goal of >or=1,000 kcal/week, compared with 1/3 in the U.S. The most disconcerting finding was the Taiwan unique U-shaped prevalence for males, with the 25-44 age group being the least active, >or=65 age group being the most active; and S-shaped for females, lowest at age 18-24 years and highest at the two older groups (45-64 and >or=65 years). LTPA was under-appreciated, particularly among the most productive work force (25-44-year group), who exercised with a prevalence only 1/4 of their U.S. counterparts. Expressing LTPA in kcal makes direct comparison easier. Invoking a goal of >or=750 kcal/week for Asians, attainable by exercising 4 hours/week, can facilitate nutritionists in assessing LTPA adequacy. Currently, 4/5 of adults in Taiwan failed to reach this goal. Recognizing the concept of cumulative energy expenditure, in contrast to disciplined daily work for 5 or more days, will encourage the infrequent exercisers such as "weekend warriors" to continue with their activities.