Calorie Deficit at 400 lbs: How Much to Eat to Lose Weight
At 400 lbs, a lightly active woman eats about 2,919 calories a day to lose 1 lb a week, and a man about 3,265. Full table by activity, plus how long 10 and 20 lb take.
At 400 lbs, a 35-year-old lightly active woman of average height loses about 1 lb a week eating 2,919 calories a day. A man of average height at the same weight and activity can eat 3,265. Both numbers are maintenance minus a 500-calorie deficit, the default Nouri applies for a weight loss goal.
Your height, age, and activity move these numbers, so run the full calorie deficit calculator for your own target, or jump to another weight below.
How these numbers are calculated
Maintenance (TDEE) uses the Mifflin-St Jeor equation (women: 10 x kg + 6.25 x cm - 5 x age - 161; men: same but + 5) times an activity multiplier, rounded, exactly as the Nouri app and the deficit calculator compute it. The target is maintenance minus the deficit, rounded, and never below 1,200 calories. 400 lbs is about 181 kg.
Mifflin-St Jeor needs height and age, so the tables use age 35 and the CDC's average measured US adult height: 5'3.5" (63.5 in) for women and 5'9" (68.9 in) for men. They are examples, not your number.
Women at 400 lbs (5'3.5", age 35)
| Activity | Maintenance | 500 deficit | 750 deficit |
|---|---|---|---|
| Sedentary (x1.2) | 2,984 | 2,484 | 2,234 |
| Lightly active (x1.375) | 3,419 | 2,919 | 2,669 |
| Moderately active (x1.55) | 3,854 | 3,354 | 3,104 |
| Very active (x1.725) | 4,289 | 3,789 | 3,539 |
| Extremely active (x1.9) | 4,724 | 4,224 | 3,974 |
Men at 400 lbs (5'9", age 35)
| Activity | Maintenance | 500 deficit | 750 deficit |
|---|---|---|---|
| Sedentary (x1.2) | 3,286 | 2,786 | 2,536 |
| Lightly active (x1.375) | 3,765 | 3,265 | 3,015 |
| Moderately active (x1.55) | 4,244 | 3,744 | 3,494 |
| Very active (x1.725) | 4,723 | 4,223 | 3,973 |
| Extremely active (x1.9) | 5,203 | 4,703 | 4,453 |
A 500 deficit is about 1 lb a week at 3,500 calories per pound, and 750 is about 1.5 lb. Your activity multiplier already counts exercise, so do not eat back workout calories on top.
How long to lose 10 and 20 lbs from 400
Lightly active, same example heights and age. Each projection holds the daily target fixed and recomputes the burn from each week's new weight, the same math as the goal weight date calculator, so loss slows a little as you go.
| Who | Deficit | Daily target | Lose 10 lb | Lose 20 lb |
|---|---|---|---|---|
| Women | 250/day | 3,169 | 23 weeks | 55 weeks |
| Women | 500/day | 2,919 | 11 weeks | 23 weeks |
| Women | 750/day | 2,669 | 7 weeks | 14 weeks |
| Men | 250/day | 3,515 | 23 weeks | 55 weeks |
| Men | 500/day | 3,265 | 11 weeks | 23 weeks |
| Men | 750/day | 3,015 | 7 weeks | 14 weeks |
The 3,500-calories-per-pound rule is an estimate, and water shifts can hide fat loss for a week or two. Treat the weeks as a planning range and let your two-week scale trend have the final word. Need your daily protein too? See the protein intake calculator.
Other body weights
FAQ
How many calories should I eat to lose weight at 400 lbs?
With a standard 500-calorie deficit and light activity, about 2,919 a day for a 5'3.5" woman and 3,265 for a 5'9" man, both age 35. Moderately active, it is 3,354 and 3,744. Taller, younger, or more active people get a higher number.
What is maintenance at 400 lbs?
Mifflin-St Jeor puts resting burn at about 2,486 calories for the example woman and 2,738 for the example man. Multiplied by activity, maintenance runs from 2,984 to 4,724 for her and 3,286 to 5,203 for him.
How long does it take to lose 20 lbs from 400?
At a 500-calorie deficit and light activity, about 23 weeks for the example woman and 23 weeks for the example man, with the burn recomputed every week as weight drops. A 750 deficit cuts that to 14 weeks and 14 weeks.
Is a 750-calorie deficit too aggressive?
It is the top of the sensible 250 to 750 range. At 400 lbs it means about 2,669 a day for the lightly active example woman and 3,015 for the man. Nouri never sets a target under 1,200, and if the math lands there, talk to a healthcare provider before going lower.
Why does the time to lose 10 lb not double for 20 lb?
Because a lighter body burns less. The example woman takes about 11 weeks for the first 10 lb and 23 weeks for 20 at the same daily target, since the deficit shrinks a little each week. Rerunning your numbers every 10 lb keeps the pace up.
Sources
- Mifflin MD, St Jeor ST et al., "A new predictive equation for resting energy expenditure in healthy individuals," American Journal of Clinical Nutrition, 1990. pubmed.ncbi.nlm.nih.gov/2305711
- CDC National Center for Health Statistics, FastStats: Body Measurements (measured data, August 2021 to August 2023). cdc.gov/nchs/fastats/body-measurements.htm