A 12% decline in activity and 4 lbs of body fat in 8 weeks

Globally, people have experienced significant reductions in physical activity since the onset of the COVID-19 pandemic.  This has been quantified by activity tracking.  As outlined in the following paragraphs, activity decline and limitations on movement could theoretically lead to a reduction in calorie expenditure and an increase in body fat over a 2-month period, and other health concerns.

Fitbit tracking data reported that Americans, on average, experienced a 12% decline in activity levels for the week ending on March 22nd, 2020, compared with the same week in 2019.  The 12% decline was considerably larger in magnitude than the previous week (ending March 15th, 2020). This likely underestimates the activity declines in the weeks after as the shelter-in-place orders continued to take effect across many of the states.

The decline in activity, however, was not uniform across the United States, nor across the world.  Americans living in metropolitan areas showed declines of at least 18% in some larger cities such as San Francisco and New York.  In countries such as Spain the reduction in activity was 38% while in Australia it was 4%.

Lowered activity levels tend to compound preexisting concerns related to sedentary lifestyles — a characteristic of populations in developed countries.  Activity guidelines of 150 mins of moderate exercise/week for optimal health and wellbeing is recommended by many health organizations.


Is this reduction in activity meaningful?


It’s important to note that the activity data extracted by Fitbit represents the average reduction in steps per day.  This decline could reflect a decrease in incidental daily activity, and the temporary closing of fitness centers.  However, there are caveats regarding the data.  For example, we don’t know the reduction in activity as it correlates to intensity or distribution in any day or across the week. We also don’t know if the Fitbit users represent all demographics or socioeconomic levels including children, or people who differ in race, ethnicity, income, health status and typical activity levels. For these reasons, we should consider the data with caution.  Given the rapid and dramatic world-wide reductions in activity levels of Fitbit users, we can, however, extrapolate several probable consequences these changes in activity levels.

Calculations, along with some assumptions, demonstrate probable consequences to body weight and health over this period. We will assume for this purpose, the 12% reduction in the steps/day for Americans is directly translated to a 12% reduction in caloric expenditure (or caloric ‘burn off’).  In this case, for the average 2000 kilocalories (kcals)/day diet, a 12% reduction in activity is equivalent to 240 kcals/day that was not expended. Assuming there was no adjustment in caloric intake to offset the decline in activity, the average American, would, therefore, preserve  — rather than expend — 240 calories/day during this period. This 240 kcal equivalent is a ~2.5 mile walk or 30 minutes of home exercises.


How quickly do we gain fat?


One pound of body fat is equivalent to 3500 kcals. Theoretically, given a consistent 12% reduction in activity — and 12% reduction in caloric expenditure — the average American would gain one pound of body fat in 14.5 days.  Over the duration of 8 weeks, this equates to a gain of ~4 lbs in body fat.

These calculations do not consider other changes in behaviors that could offset or, alternatively, accelerate weight and body fat gain. Certainly, a decrease in caloric intake would offset the lower activity levels.  However, an increase in food intake would accelerate body fat gain above 4 lbs over 8 weeks. Furthermore, the consequences of such inactivity would likely result in a loss of muscle mass and aerobic capacity (cardiovascular fitness) over 8 weeks, particularly for older adults who already have diminished capacity. The health consequences of inactivity could also be long lasting given the close link between activity, fitness and disease.


What can I do?

This snapshot of reduced activity levels raises many questions and opportunities for intervention, should an extension or reinstatement of shelter-in-place orders occur.  While travel and our daily movements may become less restrained, social distancing requirements will continue to impose limitations and constraints on activity choices.  Therefore, performing exercise in a home-based or a small group setting is a practical and feasible option.  Exercise regimes and challenges, recommended by SimpliMove.health, are within reach of those who recognize the importance of daily movement.

When meeting the recommended activity levels per day, the benefits of exercise are tremendous and well worth the effort for increased quality of life, optimal mental health, strength, endurance and independence.  Consider the change in your own activity levels over the last 2 months during the shelter-in-place orders.  What will you do to stay active and cash in on ways to stay active?

Explore one of our SimpliMove.health exercise challenges below to offset sedentary behavior during the COVID-19 pandemic:

Challenge 1       7-Day strength-based exercises

Challenge 2       7-Day strength-based exercises

Challenge 3       6 Week aerobic exercise – running

Challenge 4       6 Week aerobic exercise – walking

Challenge 5       7-Day strength-based exercises

Challenge 6       7-Day strength-based exercises

Challenge 7       7-Day strength-based exercises