How Liftbite calculates your numbers

The formulas, reference values, and data sources behind your calorie, macro, and nutrition numbers.

Last updated on June 16, 2026

Liftbite turns the details you enter into daily targets using published formulas and reference values. These numbers are estimates to guide you. They are not medical advice. Liftbite is not a medical device, dietitian, or doctor. Talk to your doctor before making medical decisions or big changes to how you eat or train.

Your daily calories

We start with your Basal Metabolic Rate (BMR), the calories your body burns at rest, using the Mifflin-St Jeor equation:

  • Men: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
  • Women: (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161

We then multiply your BMR by an activity factor based on how many times you train each week to estimate the calories you burn per day (your Total Daily Energy Expenditure, or TDEE):

  • 0 to 1 workouts per week: 1.2
  • 2 to 3 workouts per week: 1.375
  • 4 to 5 workouts per week: 1.55
  • 6 to 7 workouts per week: 1.725
  • 8 or more workouts per week: 1.9

For a weight goal we add or subtract calories from your TDEE, and we never recommend a target below 1,200 calories a day.

The Mifflin-St Jeor equation was published in the American Journal of Clinical Nutrition (1990) and was found to be the most accurate of the common equations in a systematic review by the Academy of Nutrition and Dietetics (2005).

Your weight-change pace

Each pace (slow, recommended, or fast) assumes roughly 7,700 calories per kilogram of body weight, which sets how many calories we add or subtract per day. A steadier pace is gentler and easier to sustain. National guidance describes a gradual rate of about 0.5 to 1 kg (1 to 2 lb) per week as sustainable.

Projected dates assume you keep a consistent pace and will shift as your real weigh-ins come in. See the NIH Body Weight Planner for how energy balance affects body weight.

Your protein, carbs, and fat

  • Protein scales with your body weight and goal, about 1.6 to 2.0 grams per kilogram.
  • Fat is set near 27% of your daily calories.
  • Carbs fill the remainder of your daily calorie target.

Protein targets follow the International Society of Sports Nutrition position stand on protein and exercise (2017). Fat and carbohydrate shares sit within the macronutrient ranges in the Dietary Guidelines for Americans.

Vitamins and minerals

Default targets for nutrients like fiber, sodium, potassium, calcium, and iron use the FDA Daily Values for a 2,000-calorie reference diet. You can adjust any target in the app under Nutrition goals.

Food calories

When you search foods or scan a barcode, nutrition comes from the FatSecret Platform nutrition database. When you photograph or describe a meal, AI reads it and returns an estimate. Every entry is yours to review and edit before logging, and these results can be wrong.

Workout calories

When Apple Health has no active-energy reading for a session, we estimate it from exercise intensity, your body weight, and how long you trained:

  • Calories = MET value x weight in kg x duration in hours

MET values come from the Compendium of Physical Activities (Ainsworth et al., 2011).

A reminder

These numbers are estimates that help you track and adjust, not medical advice or guaranteed outcomes. Always talk to your doctor before making medical decisions, and stop and seek help if something feels unsafe. See our Terms of Use and Privacy Policy for more.