ButtMaxx gives general nutrition and training guidance for healthy adults. This page explains how each number is calculated and links the published work it rests on. None of it is medical advice: if you are pregnant or breastfeeding, have a history of disordered eating, kidney disease or any other condition, or take medication that affects appetite or weight, talk to a doctor or registered dietitian before following any target in the app.

Your resting energy is estimated with the Mifflin-St Jeor equation from your weight, height, age and sex, then multiplied by an activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active) for your day-to-day activity outside workouts. The result is never set below your resting energy or below 1,400 kcal.

Grow adds a small surplus of about 250 kcal a day, Strong about 150 kcal, Sculpt stays at maintenance, and Lean uses a moderate deficit of about 300 kcal with higher protein so muscle is kept while fat is lost. For beginners with a body mass index of 27 or above, the surplus is deferred: new lifters build muscle at maintenance in their first months, so the app waits before adding calories.

The daily protein target is 1.8 g per kg of body weight (2.0 g/kg on the Lean goal and when a surplus is deferred), kept inside 1.6 to 2.2 g/kg. Meal hints point at 25 g or more per meal, since spreading protein over three or four meals of roughly 0.4 g/kg supports muscle growth better than one large serving; the daily total still matters most.

Fat is set at 28 percent of calories, inside the 20 to 35 percent range recommended for adults. Carbohydrates fill the remaining calories, never below 80 g a day. The fiber target is 14 g per 1,000 kcal.

The sugar cap is 10 percent of calories, the World Health Organization's limit for free sugars. For sodium the app uses a soft ceiling of 3,000 mg a day, above the 2,000 mg (WHO) and 2,300 mg (Dietary Guidelines) general-population limits, because women who train several times a week lose sodium in sweat. It is a nudge, not a medical limit: anyone with high blood pressure or a kidney or heart condition should follow their doctor's figure instead.

Foods are grouped as whole, processed or ultra-processed following the NOVA classification, using the Open Food Facts NOVA group where one exists and the AI estimate otherwise.

The daily Health Score is ButtMaxx's own index, built from the targets above. A day starts at 100 and loses points for protein below 90 percent of target, fiber below 70 percent, calories more than 5 percent over, sugar or sodium over their caps, and for the share of ultra-processed and processed food. 85 and above reads as an elite day, 70 to 84 as solid. It is a habit tracker, not a validated clinical measure, and it only scores what you log.

The in-app coach follows the same protein and calorie rules. It may mention creatine monohydrate at 3 to 5 g a day as a well-studied extra, and 7 to 9 hours of sleep for recovery. It gives no other supplement doses and no medical advice. In the weekly check-in it reads one week of weight change as noisy, and explains that a small gain while training and eating near target usually reflects new muscle and the water and glycogen it stores, not fat.

Sessions put compound lifts first, progress load only after every set hits its target, keep 2 to 3 minutes of rest on compounds, aim for 10 to 20 hard sets a week per muscle, and leave at least a day between heavy glute sessions. Every plan trains the glutes 2 to 4 times a week, since training a muscle at least twice a week builds more of it than once. Sessions open with a lighter warm-up set before the first heavy lift, and every fifth week is a lighter deload week. When you report still being sore, heavy compound lifts start about 12.5 percent lighter that day, and after two sore sessions in a row exercises with more than two sets drop one. Two sessions in a row with missed reps bring the weight about 10 percent lower. All of this follows the progression and recovery advice of the ACSM position stand below.

The comparison shown at the start of the app comes from a randomized study in 124 untrained young men who followed the same 11-week program, one group with one coach per 5 people and one with one coach per 25: bench press strength rose about 16 percent with closer coaching against about 10 percent with less, and only the closely coached group gained significant knee-extensor strength. A 2023 study in trained men and women found the same direction: supervised training produced more muscle growth and better adherence than the same program done unsupervised. ButtMaxx guides each set (load, reps, rest and form cues) to bring that structure to training on your own; it is not a personal trainer, and results vary.

The calories shown after a workout are an estimate: 4.5 MET for time spent lifting and 1.8 MET for rest between sets, multiplied by your body weight and the time spent, following the standard MET method. It is a motivator, not a measurement, and is not added to your daily food target.

Spotted an error, or a newer study? Email info@buttmaxx.app. The app's health and safety terms are in the Terms of Service, section 8.