Quarantine Activity Calculator
Staying home changes your daily energy expenditure more than most people expect. This calculator uses the Mifflin-St Jeor equation for your basal metabolic rate and MET-weighted activity hours to compute your Total Daily Energy Expenditure (TDEE) before and during quarantine. You get the calorie gap, a physical activity level comparison, and a recommended calorie adjustment so your weight stays on track.
Why quarantine often causes unintended weight gain
When you shift from a typical working day to home isolation, you lose a surprising amount of incidental movement: the commute walk, trips to the office kitchen, standing in queues, lunch-hour errands. Research published after the 2020 lockdowns consistently found that daily step counts fell by 30-60% in many populations during strict stay-at-home orders, reducing total energy expenditure by 300-500 kcal/day in moderately active adults. If food intake stays the same, that gap translates to roughly 0.3-0.7 kg of weight gain per month - invisible week to week but measurable over a quarantine period.
How this calculator works: BMR, PAL, and TDEE
Your Basal Metabolic Rate (BMR) is the energy your body burns at complete rest, computed here with the Mifflin-St Jeor equation (the most validated formula for healthy adults): BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5 (male) or -161 (female). Total Daily Energy Expenditure (TDEE) is then BMR multiplied by a Physical Activity Level (PAL) factor. PAL is derived from the MET (metabolic equivalent) values of each activity type, weighted by the hours spent on it across a 24-hour day. Activities given higher MET values (running 8.0, HIIT 8.5) move the PAL needle much more per hour than sedentary time (1.3) or light housework (2.5). The calculator computes PAL and TDEE for both your pre-quarantine and quarantine routines and shows you the daily gap.
Closing the calorie gap without a gym
The two levers are burning more and eating a little less. Home HIIT workouts (20-30 minutes, 3-4 times a week) can recover 150-300 kcal/day of the deficit. Body-weight strength training - push-ups, squats, lunges - preserves muscle mass that would otherwise shrink, keeping your BMR higher. Even simple behavior changes help: standing while on video calls, pacing during phone calls, doing a short walk before meals. On the dietary side, cutting 100-200 kcal/day by reducing liquid calories (alcohol, juice, specialty coffee) or portion-trimming one meal is usually easier than a full diet overhaul.
Interpreting your Physical Activity Level
The WHO/FAO classifies a PAL below 1.55 as sedentary and notes that sustained PALs in this range are associated with higher rates of metabolic disease. A PAL between 1.70 and 2.00 is moderately active and the range most easily maintained with 30 minutes of brisk activity per day. During quarantine, many people drop from a pre-pandemic PAL near 1.70 to a quarantine PAL around 1.40-1.50. The gauge visual above your results places your quarantine PAL on this scale so you can see at a glance where you sit. PAL above 2.0 is hard to sustain without deliberate daily training.
Physical Activity Level (PAL) reference ranges
| PAL range | Category | Typical lifestyle |
|---|---|---|
| 1.00-1.39 | Very sedentary / bed rest | Bedridden; minimal movement |
| 1.40-1.55 | Sedentary | Desk work, no deliberate exercise |
| 1.56-1.69 | Lightly active | Desk work + 1-2 short walks/day |
| 1.70-1.99 | Moderately active | Some walking and light exercise |
| 2.00-2.40 | Very active | Regular moderate to intense exercise |
FAO/WHO/UNU 2001 classification. PAL = TDEE / BMR. Most people working from home fall in the 1.40-1.60 range.
Frequently asked questions
What is the Mifflin-St Jeor equation and why does this calculator use it?
The Mifflin-St Jeor equation (1990) is widely considered the most accurate BMR formula for healthy adults. A large 2005 meta-analysis in the Journal of the American Dietetic Association found it predicted resting energy expenditure within 10% of measured values for the majority of subjects, outperforming older formulas like Harris-Benedict. It uses weight, height, age, and sex, all of which are easy to measure accurately.
What is a MET value and how is it used here?
MET stands for metabolic equivalent. An activity with a MET of 3.5 burns 3.5 times as many calories as sitting completely still. The Ainsworth Compendium of Physical Activities assigns MET values to hundreds of activities. This calculator uses representative MET values for each activity type (e.g. running 8.0, yoga 3.0, sedentary 1.3) and weights them by the hours you spend on each to compute a 24-hour average PAL.
How accurate is the calorie change estimate?
The figure is a physiological estimate, not a precise measurement. Individual variation in metabolism, body composition, and non-exercise activity thermogenesis (NEAT) means actual TDEE can differ by 10-15% from the formula output. Use the result as a directional guide: a drop of 300 kcal/day is meaningful and worth addressing; whether the true figure is 280 or 320 matters less.
Does the weekly weight change projection account for metabolic adaptation?
No. The projection assumes a fixed calorie surplus or deficit, but in reality your BMR falls slightly as you lose mass and your body adapts. The first two to three weeks of a deficit are usually the most productive; after that, weight change slows. Treat the weekly figure as the early-period rate, not a guarantee sustained over months.
Can I use this for children or teenagers?
The Mifflin-St Jeor equation is validated for adults aged 18 and over. Children and adolescents have higher mass-specific metabolic rates and different activity patterns. For those under 18, a pediatric-specific BMR formula and age-appropriate activity guidelines should be used instead.
What PAL should I aim for during quarantine?
The WHO recommends a PAL of at least 1.70 for good long-term health. During strict quarantine this can be hard to achieve without deliberate exercise, but a PAL near 1.60 is realistic with 30 minutes of moderate home activity daily. Anything below 1.50 over several weeks is associated with muscle loss and metabolic changes that persist after quarantine ends.
Sources
- Mifflin MD et al. (1990) - A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition
- Ainsworth BE et al. (2011) - 2011 Compendium of Physical Activities. Medicine and Science in Sports and Exercise
- FAO/WHO/UNU (2001) - Human Energy Requirements. Food and Agriculture Organization of the United Nations