17 Fit Calculators Calorie deficit calculator
Calorie deficit calculator your calories for weight loss and when you’ll reach your goal
Enter your sex, age, height, weight, goal weight and activity. You’ll see how many calories to eat, your daily deficit, your weekly pace and roughly when you’ll get there.
The date moves with you. In 17 Fit, once you’ve logged three weigh-ins over two weeks, the forecast follows your real weight trend instead of the formula, and the plan adjusts every week.
You’ll reach your goal in
29 weeks
- Daily calories
- 1,620 kcal
- Deficit
- −402 kcal a day
- First week
- −0.37 kg, 0.5 % of your weight
- To lose
- 10 kg
- Straight-line estimate
- 28 weeks
That goal puts your BMI below 18.5, under the healthy range, so the calculator doesn’t plan for it. For your height, the healthy range starts at 50.4 kg.
17 Fit never suggests a goal below a BMI of 20, which for your height is 54.5 kg.
At this pace it would take more than two years, so there’s no date: the deficit is too small to plan with.
The plan never goes below 1,200 kcal a day, as in the app, so your deficit is less than 20 %.
This pace is more than 1 % of your weight a week, faster than 17 Fit recommends.
Enter an age of 15 to 90, a height of 120 to 230 cm, and current and goal weights of 35 to 250 kg, with the goal below your current weight.
An estimate: real weight loss isn’t a straight line, and water moves the scale from day to day.
1,620 kcal a day; you’d reach your goal in about 29 weeks.
How the date is worked out
The same plan 17 Fit gives for weight loss, followed week by week.
- Maintenance Your basal metabolic rate by Mifflin–St Jeor times your activity factor: the calories that keep your weight steady.
- The deficit The plan is 20 % under maintenance and never below 1,200 kcal a day for women or 1,500 for men.
- The pace A kilo of body fat holds about 7,700 kcal, so the week’s deficit divided by 7,700 is the week’s loss in kilos.
- Week by week Each week the plan is worked out again at the new weight. A lighter body burns less, so the pace slows and the date comes later than a straight line suggests.
How long it takes to lose 5, 10 or 15 kg
Worked out the same way, week by week. Your own date is in the calculator above.
| Profile | −5 kg | −10 kg | −15 kg |
|---|---|---|---|
| Female, 30 years, 165 cm, 75 kg, light activity | 14 weeks | 29 weeks | 44 weeks |
| Female, 45 years, 162 cm, 85 kg, minimal activity | 16 weeks | 33 weeks | 50 weeks |
| Male, 30 years, 180 cm, 90 kg, moderate activity | 10 weeks | 20 weeks | 30 weeks |
| Male, 45 years, 178 cm, 100 kg, light activity | 11 weeks | 22 weeks | 34 weeks |
Questions and answers
How long does it take to lose 10 kg?
It depends on your size and activity. For example, a woman who is 30 years old, 165 cm tall and lightly active would start on 1,620 kcal a day and go from 75 to 65 kg in about 29 weeks. A straight-line estimate says 28 weeks, but the body burns less as it gets lighter.
How big a calorie deficit is safe?
About 20 % under maintenance, as 17 Fit plans it: for most people that’s 300–600 kcal a day. Women shouldn’t go under 1,200 kcal a day, or men under 1,500, without medical supervision.
How fast can I safely lose weight?
Up to 1 % of your body weight a week: for most people, 0.5–1 kg. Any faster and you’re likely to lose muscle along with the fat.
Why does weight loss slow down?
A lighter body needs less energy, so the same plate makes a smaller deficit. The calculator works the plan out again every week, which is why its date is later than a straight-line estimate at 7,700 kcal a kilo.
Why doesn’t the scale follow the forecast?
Water, salt and food in the gut move the scale by a kilo or more from day to day. Judge the trend over two to three weeks, not a single weigh-in.
Can I reach my goal faster by eating less?
Not safely below 1,200 kcal a day for women or 1,500 for men: under those floors it’s hard to get enough protein, vitamins and minerals, and you lose more muscle. The calculator never plans below them.
Who is the calculator not for?
Pregnant and breastfeeding women, children and teenagers, people with an eating disorder now or in the past, and anyone with a condition that needs a therapeutic diet. Please plan with a doctor or dietitian instead.
17 Fit
A goal date that follows your real weight
17 Fit draws the trend through your weigh-ins, shows when you’ll reach your goal at your real pace and warns you if it’s faster than 1 % of your weight a week.
- Weight trend and the date you’ll reach your goal
- Calories and macros from a photo of your plate
- Free food diary, no sign-up and no ads
