Protein-first logic
Muscle preservation target = 1.4 g/kg of goal weight.
Protein is set before fat and carbohydrate so you plan meals around amino acid adequacy, not whatever calories are left after skipping meals.
Calories, protein & hydration on GLP-1s
GLP-1 Macro & Calorie Calculator
Calories and protein-first macros for GLP-1 weight-loss therapy (semaglutide, tirzepatide, and common brand options). TDEE from Mifflin-St Jeor, 500 kcal deficit, hydration and fiber for GI comfort.
01
UnitsPersonal stats
Sex (BMR constant)
Used for BMR, TDEE, and hydration estimate.
02
Activity & meds
Light activity 1–3 days/week
Selection documents your protocol; energy math uses stats above, not dose.
03
Goals
Muscle preservation target scales at 1.4 g protein per kg of this weight.
Muscle preservation target
104.8 g
Distributed across meals; prioritize complete sources and resistance training as prescribed.
STEP trial optimized — protein emphasis aligns with intensive lifestyle support models used alongside GLP-1 therapy in trials such as STEP.[1]
GLP-1 deficit target
1665 kcal
BMR 1575 kcal · TDEE 2165 kcal
Activity ×1.375 (Light)
Dietary fat allocation
46.3 g
25% of target calories (~416 kcal)
Carbohydrate remainder
207.4 g
Non-protein, non-fat energy (~830 kcal)
Hydration (fluid oz)
133 oz
~3933 ml
Dietary fiber target
30 g
GI-friendly benchmark on GLP-1 therapy; titrate if bloating.
Logic & sources
Mifflin-St Jeor basal metabolic rate, activity-adjusted TDEE, fixed 500 kcal deficit, protein-first partitioning (1.4 g/kg goal weight; fat 25% of calories; carbohydrate residual), hydration heuristic, and fiber target for GI tolerance.
[1] STEP trials combined pharmacotherapy with intensive lifestyle intervention; this calculator borrows that protein-forward framing for educational planning—not a prescription.
Notice
For orientation only. GLP-1 medications require medical supervision; do not change therapy based on calculator output.
Nutrition on GLP-1 Therapy
GLP-1–based drugs for obesity or diabetes blunt appetite; the practical risk is under-eating low-quality food and losing lean mass. The notes below explain the clinical priorities encoded in this tool (protein-first partitioning, transparent energy math, GI support)—not a duplicate of the live results above.
Clinical orientation
Deficit without guesswork
TDEE comes from Mifflin-St Jeor × activity, then subtract 500 kcal.
It is transparent math you can reconcile with your clinician or dietitian—not a black-box “AI plan.”
Fiber & hydration
30 g fiber supports bowel regularity when gastric emptying slows.
Fluid ounces scale with current weight; still individualize for cardiac, renal, or GI conditions.
STEP-informed framing
Trials like STEP combined semaglutide with intensive lifestyle support.
This tool borrows that protein-forward, nutrient-density mindset for planning—it does not copy trial menus or replace medical nutrition therapy.
GLP-1 Macro & Calorie Calculator: Protein, Deficit & Hydration for Ozempic, Wegovy, Mounjaro, Zepbound
For adults using GLP-1 therapy for weight loss (e.g., semaglutide or tirzepatide), compute a transparent calorie target (Mifflin-St Jeor TDEE − 500 kcal), a muscle preservation protein goal (1.4 g/kg goal weight), fat and carbohydrate partitions, fluid ounces from current weight, and a 30 g fiber benchmark for GI health.
What This Calculator Does
Purpose & scope
- Who it helps:Adults on or considering GLP-1-based obesity pharmacotherapy who want a nutrient-dense, muscle-aware macro scaffold to discuss with a clinician or registered dietitian.
- What it does not do:It does not personalize for pregnancy, eating disorders, advanced kidney disease, elite sport, or tube feeds. It is not a prescription. For trial-style time-to-goal estimates by medication and dose, use the related GLP-1 weight loss calculator linked below this article.
All numeric outputs (calories, macros, fluid, fiber) are computed live in the tool above as you change inputs—see the subtitle on this page for a compact list. This section covers who should use it and what it is not.
GLP-1 Drugs, Weight Loss, and Why Calories Still Matter
Context
- Related planning tools:For height–weight context, a BMI calculator complements these macros. For broader calorie scenarios outside the fixed 500 kcal deficit model here, a general calorie calculator may be useful for comparison.
Medications such as Ozempic, Wegovy, Mounjaro, and Zepbound have made GLP-1–based therapy a mainstream part of obesity and diabetes care. They work mainly by helping people eat less, not by replacing the need for adequate protein, fluids, or fiber. A dedicated weight loss calculator that only projects scale change cannot, by itself, tell you whether today’s meals covered amino acids or roughage—this tool is meant to fill that planning gap next to your prescriber’s advice.
How the Math Works
Equations (summary)
- Low calorie warning:If target calories fall below ~1200 kcal/day (female sex selection) or ~1500 kcal/day (male sex selection), the tool surfaces a subtle warning—common clinical caution thresholds, not universal rules.
- Conflicting macros:If protein and mandated fat exceed total calories, the tool explains that the model is inconsistent at that intake and suggests professional adjustment.
BMR uses Mifflin-St Jeor with sex-specific constant; TDEE multiplies BMR by an activity factor from 1.2 (sedentary) through 1.9 (athlete). Target calories = TDEE − 500. Protein = 1.4 × goal weight (kg). Fat calories = 25% of target calories; carbohydrate calories fill the remainder (4 kcal/g protein and carbohydrate, 9 kcal/g fat).
GLP-1 Macro & Calorie Calculator FAQ
What are GLP-1 medications?
GLP-1 receptor agonists mimic a hormone your gut releases after meals. They strengthen fullness signals, slow stomach emptying, and help regulate blood sugar. For weight management, common weekly injectables include semaglutide (brand names include Ozempic for type 2 diabetes and Wegovy for chronic weight management) and tirzepatide (Mounjaro for diabetes, Zepbound for obesity). They are prescription drugs—eligibility, titration, and monitoring belong with your clinician.
Why is protein based on goal weight and not current weight?
This tool uses 1.4 g per kg of goal body weight as a muscle preservation anchor during weight loss. Anchoring to goal weight keeps protein from falling as you lose mass, which helps reduce sarcopenia risk when intake is suppressed on GLP-1 therapy. Your clinician may adjust this for kidney disease, higher training load, or other factors.
Is a 500 kcal deficit safe on Ozempic or Zepbound?
A fixed 500 kcal deficit is a common textbook default (~0.5 kg fat loss per week if perfectly adhered to). On GLP-1 medications, appetite is often lower, so some people land near or below that level without trying. If your target drops below typical clinical floors (often ~1200 kcal/day for many women, ~1500 kcal/day for many men), discuss sustainability, nutrient adequacy, and monitoring with your provider. This calculator flags that case but does not replace medical judgment.
Why 30 g of fiber?
GLP-1 drugs slow gastric emptying; constipation and bloating are common. A fiber target near 30 g/day is a practical benchmark aligned with general adult recommendations and GI-focused counseling, but you may need to titrate slowly with fluids to avoid discomfort. Ask your clinician if you have IBD, strictures, or other contraindications.
How is hydration estimated?
The calculator uses current weight in pounds × 0.67 to suggest daily fluid ounces—a simple heuristic, not a prescription. Needs vary with sweat loss, climate, kidney or heart conditions, and medications. Use thirst, urine color, and clinician advice as primary guides.
Does my medication dose change these numbers?
The energy and macro math uses your age, sex, height, current weight, activity level, and goal weight. Medication selection is recorded for context only; dose titration is not modeled here. Pair this tool with the GLP-1 timeline calculator if you want trial-based weight-loss pacing.
Do I still need calorie and protein targets if GLP-1 already curbs my appetite?
Many people eat less on these drugs without manual tracking, but total energy and protein still shape whether you lose mostly fat or also lean tissue, and whether you meet micronutrient needs on a smaller plate. This calculator offers a transparent ballpark to discuss with your care team—not a substitute for individualized medical nutrition therapy.
How does BMI fit in alongside this macro calculator?
BMI is a simple height–weight index clinicians often use to discuss risk categories; it does not measure body composition or tell you what to eat. If you want a BMI figure to compare with your goal weight, use a BMI calculator, then return here for calorie and macro targets grounded in your stats and activity.
Sources & citations
References used for the calculation method and definitions. Links open in a new tab when available.
[1]
Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)
Wilding JPH, et al. N Engl J Med. 2021. Pivotal STEP trial: semaglutide 2.4 mg weekly with a reduced-calorie diet and increased physical activity. Cited for the “STEP-informed” lifestyle-integrated framing used in this tool—not for any specific macro prescription from the trial protocol.
[2]
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)
Jastreboff AM, et al. N Engl J Med. 2022. Key obesity trial for tirzepatide (Mounjaro/Zepbound class). Included because this calculator’s medication list overlaps that evidence base; energy and macro math here are not dose-specific.
[3]
A new predictive equation for resting energy expenditure in healthy individuals
Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990. Original Mifflin–St Jeor equation used for BMR in this calculator.
[4]
Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients)
National Academies (Institute of Medicine) macronutrient report documenting adequate intakes for dietary fiber by life stage. The 30 g/day target in this tool is a practical counseling benchmark for many adults on GLP-1 therapy, not a substitute for individualized goals.
[5]
Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults
National Heart, Lung, and Blood Institute (1998; archived PDF). Widely referenced historical basis for roughly 500 kcal/day deficit as a standard teaching target for gradual weight loss; modern care should individualize with a clinician.
Medical Estimation Note
Estimates Only: Nutrition targets use published equations (e.g., Mifflin-St Jeor) and simplified deficit and macro rules. They are not individualized medical nutrition therapy.
Individual Variation: Energy needs, tolerance, comorbidities, and medication response differ. Protein, fluid, and fiber goals should be confirmed with your care team.
Consult Your Provider: Consult your healthcare provider or registered dietitian before adopting a calorie or macro plan, especially on GLP-1 therapy.
Privacy First: All calculations are performed locally in your browser. No health data is stored or transmitted to any server.
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