Lose It Weight Loss Calculator

Model weight loss using energy balance, activity, and goals. Adjust timelines safely before changing habits. Review calorie targets, progress dates, and exportable results instantly.

Advanced Calculator

Use cm for metric, inches for imperial.
Required only for Katch-McArdle.
Daily planned exercise calories.
Use kg or lb based on unit choice.
Reduces TDEE by selected percentage.
Grams per kg of current body weight.
Grams per kg of current body weight.
Percentage of deficit from activity.

Example Data Table

This sample shows how different deficits can change the expected pace.

Daily Deficit Weekly Deficit Estimated Weekly Loss Comment
250 kcal 1,750 kcal 0.23 kg Slow and easier to maintain.
500 kcal 3,500 kcal 0.45 kg Common moderate target.
750 kcal 5,250 kcal 0.68 kg More aggressive for many users.
1,000 kcal 7,000 kcal 0.91 kg Needs careful review.

Formula Used

BMR: The calculator estimates resting energy with Mifflin-St Jeor, Revised Harris-Benedict, or Katch-McArdle.

TDEE: TDEE = BMR × Activity Factor + Extra Workout Calories.

Adjusted TDEE: Adjusted TDEE = TDEE × (1 − Adaptation Percentage).

Total energy gap: Weight to lose in kg × 7,700 kcal.

Daily deficit: Total energy gap ÷ available days, or weekly loss goal × 7,700 ÷ 7.

Calorie target: Adjusted TDEE − planned daily deficit.

Timeline: Days = Total energy gap ÷ effective daily deficit.

How to Use This Calculator

  1. Select your unit system first.
  2. Enter age, height, current weight, and target weight.
  3. Choose the BMR formula that matches your available data.
  4. Select your activity factor and add workout calories if needed.
  5. Choose weekly goal, target date, or calorie intake mode.
  6. Adjust adherence, adaptation, macros, and exercise share.
  7. Press calculate and review the result above the form.
  8. Use CSV or PDF buttons to save the result.

Physics Behind Weight Loss Planning

Energy Balance

Weight loss follows energy balance. The body stores extra energy. It also releases stored energy during a deficit. This calculator treats body weight change as an energy problem. It compares estimated daily burn with planned daily intake. The gap becomes the expected deficit.

Why TDEE Matters

Total daily energy expenditure is the central value. It begins with basal metabolic rate. That is the energy used while resting. Activity then raises the total. Exercise calories can also be added. A person with a higher TDEE can usually eat more while losing weight.

Planning Pace

The calculator uses 7,700 calories for one kilogram of fat mass. This is a planning estimate. Real progress may shift because water, digestion, training, sleep, and hormones can affect scale weight. For this reason, the tool includes adherence and adaptation options.

Advanced Adjustments

Adherence lowers the effective deficit. This gives a more realistic result. Adaptation lowers estimated maintenance calories. This helps model slower progress during long diets. The safety floor prevents the plan from dropping below a chosen calorie limit.

Macros and Activity

The macro section divides calories into protein, fat, and carbohydrates. Protein is based on body weight. Fat is also based on body weight. Carbohydrates receive the remaining calories. The exercise share shows how much of the deficit comes from movement.

Using the Output

Use the result as a structured estimate. Compare several goals before choosing a plan. A slower timeline may be easier to follow. A faster timeline may require larger food changes or more activity. Review results with a qualified professional when medical concerns exist.

Frequently Asked Questions

1. What does this calculator estimate?

It estimates calorie targets, daily deficits, weekly weight change, goal dates, BMI values, and macro targets using energy balance formulas.

2. Which BMR formula should I choose?

Mifflin-St Jeor is a common default. Harris-Benedict gives another estimate. Katch-McArdle is useful when you know body fat percentage.

3. Why does adherence change the result?

Most plans are not followed perfectly every day. Adherence adjusts the effective deficit, giving a more realistic estimated timeline.

4. What is adaptation allowance?

Adaptation allowance reduces estimated maintenance calories. It models the slower energy burn that may happen during extended dieting.

5. Why was my calorie target adjusted?

The calculator applies your safety floor when the chosen plan creates a very low calorie target. This protects the estimate from becoming extreme.

6. Are the results exact?

No. They are estimates. Real weight changes can vary because of water balance, digestion, activity tracking errors, and metabolic differences.

7. Can I use pounds instead of kilograms?

Yes. Select the imperial unit option. The calculator converts pounds and inches internally before running the formulas.

8. When should I seek professional advice?

Seek advice if you have medical conditions, pregnancy, disordered eating history, medication changes, or symptoms during weight loss.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.