Why this differs from other weight loss calculators
Most weight loss calculators use the rule that a pound of fat holds about 3,500 calories: eat 500 fewer a day, lose a pound a week, every week. That draws a straight line to your goal.
Real progress curves. As you lose weight, your body needs fewer calories, so the same meal plan creates a smaller gap each week. Researchers who tested the 3,500 calorie rule against real weight loss data found it overestimates how much people lose, more so the longer they diet.
This calculator works day by day. Each day it re-estimates your energy use at your new weight with the Mifflin-St Jeor equation, subtracts what you eat, and converts the gap to weight. The result is a slower, more realistic timeline.
Recalculate every 10 pounds
If you set your calories once and never change them, your weight eventually levels off at the point where that intake matches your needs. For small goals this rarely matters. For bigger goals, it can stop you well short.
The simple fix is to recalculate your target after every 10 pounds or so, which keeps your daily gap roughly the same. The calculator does this by default; untick the box to see what happens if you don't.
What to expect along the way
- The first week or two often shows a faster drop. Much of that is water and stored carbohydrate, not fat.
- Weekly numbers bounce. Salt, hormones, sleep and a late meal can move the scale 1 to 3 pounds overnight. Judge progress by your average over 2 to 3 weeks.
- A pace of 1 to 2 pounds a week is what the CDC describes as gradual and steady, and people who lose weight at that pace are more likely to keep it off.
- Losing 5% of your weight can already improve blood pressure, cholesterol and blood sugar. The calculator shows when you'd reach 5% and 10%.
Choosing a plan
The plan options cut 250 to 1,000 calories a day from what you burn at the start. Bigger cuts are faster but harder to stick to, and for smaller people they can push intake below 1,200 calories a day for women or 1,500 for men, common minimums for adults eating without medical supervision. The calculator will not go below those, which can stretch the timeline.
Not sure what you burn? The TDEE calculator shows it, and the calories burned calculator covers exercise. To check progress against your starting weight, use the weight loss percentage calculator.
Questions people ask
How long will it take me to lose weight?
It depends mostly on how big a calorie gap you keep and how much you have to lose. At about 500 calories a day below your needs, most people lose close to a pound a week at first, then a bit less as they get lighter. Enter your details above for a dated estimate.
Is losing 2 pounds a week realistic?
For people with a lot to lose, it can be at the start. It takes a daily gap of about 1,000 calories, which is hard to keep up and often not possible for smaller people without dropping below safe minimum intakes. One pound a week is a more sustainable target for most.
Why does weight loss slow down over time?
A smaller body burns fewer calories, both at rest and when moving. If you keep eating the same amount, your daily calorie gap shrinks and so does the weekly loss. Recalculating your target every 10 pounds keeps progress steadier.
Why did I lose more than predicted in the first week?
Early weight loss includes water and stored carbohydrate called glycogen, which can add several pounds in the first week or two. After that, the scale tends to follow fat loss more closely.
What should I eat once I reach my goal?
The calculator shows your estimated maintenance calories at your goal weight. It is lower than what you needed at the start, so returning to old habits is the most common reason weight comes back.
Sources
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241–247.
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet. 2011;378(9793):826–837.
- Thomas DM, Martin CK, Lettieri S, et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. International Journal of Obesity. 2013;37(12):1611–1613.
- Centers for Disease Control and Prevention. Losing Weight.