How many calories do you burn in a day?
Your maintenance number is the starting line for everything else. This gives you the estimate and the two deficits I'd use.
Your result shows here
Fill in the form and hit calculate. You'll get your maintenance estimate, two deficit targets, and the protein and fiber to go with them.
What to do with the number
Treat it as a first guess. The formula knows your height, weight, age and roughly how much you move. It doesn't know your genetics, how fidgety you are, or how honest the activity dropdown was. In validation studies it lands within 10 percent of measured resting metabolism for most adults, which is plenty to start.
Pick the deficit, eat there for two weeks, and weigh in most mornings. Average each week. If the average dropped about what you planned, the number is right. If it dropped faster, add 100 to 150 calories. If it didn't move, take 100 to 150 off. Two weeks is the shortest stretch worth judging, because water swings hide the trend in anything shorter.
Why I start at half a pound to a pound a week
A bigger deficit loses weight faster and is harder to live with. In a three-year trial, people who lost the weight in 12 weeks and people who took 36 weeks had regained about the same share of it by the end (Purcell et al., 2014, linked below). The pace that works is the one you can hold through a normal month, travel and all. Half a pound to a pound a week is where I start most people. Up to two pounds a week can work when you have a lot to lose, and the time-to-goal calculator shows what each pace costs you in calories.
Where this fits with everything else
Calories set the direction. Protein decides how much of the weight you lose is fat (protein calculator). Fiber, produce and water make the deficit easier to live with. Short sleep makes hunger louder. That's the system my clients' plans are built on, and the free guide walks through it.
What formula does this use?
Mifflin-St Jeor for resting energy, multiplied by a standard activity factor. It's the equation most clinicians and researchers use for adults, and it's as good as any formula gets without measuring your breath in a lab.
Why does the lower target stop at 1,200 or 1,500 calories?
Below those levels it's hard to get enough protein, fiber and micronutrients from food, and the hunger usually wins. If the math says you need to go lower, the better move is a slower pace or more activity. Anything lower than that belongs under a doctor's care.
Where do these numbers come from?
Resting metabolism: Frankenfield et al., J Am Diet Assoc 2005, a systematic review that found Mifflin-St Jeor the most reliable equation for adults, within 10 percent of measured values for most people. Fast versus slow loss: Purcell et al., Lancet Diabetes Endocrinol 2014. Protein: Wycherley et al., Am J Clin Nutr 2012. Fiber and water: the National Academies' Dietary Reference Intakes (fiber 38 g a day for men and 25 g for women; total water about 3.7 L for men and 2.7 L for women, with roughly 80 percent of it from drinks).
I've been eating this little and I'm not losing. Why?
Most of the time the problem is the count. Oils, sauces, bites while cooking, drinks and weekends add up fast. Track everything for two weeks, including Saturday, before concluding your body is the problem. If you've done that and the scale still won't move, book a call and we'll look at it together.
Want the rest of the system?
The 4 Boring Pillars guide covers calories, protein, activity, sleep and the weekend plan, with the research for each.
Want someone to run the numbers?
Online coaching is me setting your targets, adjusting them from your weigh-ins, and planning around your actual week. $200 a month, and the first call is free.