How the goal date is calculated
The calculator finds your maintenance calories (revised Harris-Benedict equation and your activity level), sets a daily deficit of 250, 500 or 750 kcal, and assumes about 7,700 kcal per kilogram of body fat. Days to goal = kilograms to lose x 7,700 / daily deficit.
If a pace would put you below 1,200 kcal (women) or 1,500 kcal (men), the target is held at that floor, and the date is worked out from the smaller deficit you would really have. That is the same rule the Calo AI app follows, so you will never be shown a date that only a crash diet could deliver.
Example: a 32 year old man, 172 cm and 85 kg, lightly active, aiming for 75 kg at a steady pace, would eat about 2,072 kcal a day and reach his goal in about 154 days (around 22 weeks).
Why the real date is usually a little later
The 7,700 kcal rule is a straight line, but your body is not. As you lose weight you burn slightly less, so the same intake makes a smaller deficit. Research by Kevin Hall and colleagues at the US National Institutes of Health showed the simple rule overestimates long-term loss for this reason. Treat the date as a target, recalculate every 4 to 5 kg, and look at the monthly trend rather than daily weigh-ins.
Making the date
- Track what you eat for the first few weeks, including oil and drinks. Most gaps between expected and real progress are untracked calories.
- Keep protein high (see the protein calculator) so the weight you lose is mostly fat.
- Walk more. Even 3,000 extra steps a day adds up; see the steps to calories calculator.