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Nutrition

TDEE Calculator

A free calculator that estimates how many calories you burn in a day, with a basic macronutrient split. On a GLP-1 it gives you a rough baseline for judging whether a much smaller intake is too low.

By the glp1.how editorial teamReviewed 2 min read

The TDEE Calculator (external link) is a free website that estimates your Total Daily Energy Expenditure (TDEE): the calories your body burns in a day, counting both resting metabolism and activity. When appetite suppression has you eating much less, it gives you a rough baseline to compare your intake against.

How it works

You enter your sex, age, height and weight, pick an activity level from sedentary to athlete, and can add your body fat percentage if you know it, which can improve accuracy. The calculator first estimates your Basal Metabolic Rate (BMR, the calories you'd burn at complete rest), then multiplies it by an activity factor. It shows your estimated TDEE along with your BMR, BMI and a macronutrient breakdown (inputs and outputs as of September 2026).

The macro breakdown is a generic split of your calories into protein, carbs and fat. It isn't a personalized protein target, so work out protein separately; our guide to protein, fat, and carbohydrates covers how.

Using it on a GLP-1

Appetite suppression makes it easy to lose track of what your body needs, as opposed to what you happen to be eating. A TDEE estimate gives you a rough sense of your baseline needs, so you can tell whether a much smaller intake is in a reasonable range or too low for your goals.

Treat the number as a planning input, not a figure to hit every day:

  1. Use it as a starting point for calorie goals, then refine them with your prescriber or a dietitian. Our discussion guide on talking to a dietitian or trainer can help with that conversation.
  2. Pair it with tracking. The calculator estimates what you need, and an app like Cronometer records what you actually eat. Comparing the two shows you the gap.
  3. Recalculate as you lose weight. TDEE changes as your weight changes, so a number from the start of treatment won't stay accurate. Redoing it every so often (for example, after each 10-15 lbs lost) keeps it useful.

The estimate also works as a check against eating too little, which is easy to do when appetite is low. If you're aiming for weight loss or body recomposition, knowing your baseline tells you whether you're in a deficit, at maintenance or in a surplus. And it gives you a concrete number to bring to your care team.

Limits

TDEE calculators give an estimate, and individual metabolism varies. They also can't account for any effect of the medication itself, and the evidence on that is early. In a phase 1 trial, tirzepatide increased fat oxidation in people with obesity but didn't change metabolic adaptation, the drop in energy expenditure that normally comes with weight loss (Ravussin et al., Cell Metabolism, 2025, DOI (external link)). Start from the calculator's range and adjust based on how your weight actually responds.

Research findings above are attributed to PubMed-indexed articles with DOI links.

nutritioncalculatortdeecaloriesmacros

Evidence

The source behind this article, labeled by type and strength.

Mixed findings1

Revision history

Updated 3 times since Sep 2, 2026 · show changes
  1. v4

    Evidence sources 0 → 1

  2. v3

    Summary rewritten; Body revised

  3. v2

    Body revised

  4. v1

    Change tracking began

Related guides

  • Do TDEE calculators still work after big weight loss on a GLP-1? · TDEE and BMR calculators give a useful starting estimate, but they get less reliable for people with obesity, and less reliable again after large weight loss, because of prediction-equation limits and metabolic adaptation. This guide explains why the number drifts and how to correct it against what your body is actually doing.
  • What a calorie deficit is, and how to find a healthy one for yourself on a GLP-1 · A GLP-1 medication makes a calorie deficit easier to keep, sometimes too easy. This guide covers what a deficit is, why it still drives weight loss on these drugs, what a healthy range looks like, and how to work out your own.
  • Micronutrient gaps on a GLP-1: a labs-first guide · Eating much less on a GLP-1 means taking in less iron, B12, vitamin D, calcium, folate, zinc and more, and many people start with gaps already. The evidence says the risk is real but mostly quiet, and the right response is to measure before you medicate. Here's which labs to ask about, who needs them most, the one rare deficiency that is an emergency, and how to fill gaps with food first and supplements second, without megadosing.
  • Collagen peptides on a GLP-1: what the types actually mean, and which promises hold up · Collagen is the supplement most heavily marketed to GLP-1 users, and the type numbers on the tub mean less than the label implies. Here's what Type I, II, and III are, what survives digestion, how the evidence grades for the three big promises (skin, tendons, and joints), and the one collagen myth that can set back your results.
  • Fiber on a GLP-1: how much you need, which type, and powder vs. capsules · Fiber is the second target after protein that a GLP-1 quietly makes harder to hit — and most of the advice about it online is written by companies selling fiber. Here's what the intake numbers actually say (including why the standard 25g/38g targets may be the wrong frame when you're eating far less), which types of fiber do what, why the fiber in gummies is unlikely to fix constipation, and the label math for powder vs. capsules.
  • Myth: you must avoid certain foods on a GLP-1 · There's a widely shared "banned foods" list for GLP-1 users: no fried food, no sugar, no alcohol, ever. The kernel of truth is that high-fat, greasy, very sugary meals and alcohol commonly worsen the medication's GI side effects, and clinical guidance does recommend avoiding them to manage symptoms. But no food is medically off-limits, the prescribing information lists no food interactions, and triggers are individual and usually worst while the dose is going up.

Related terms

  • TDEE (total daily energy expenditure) · The total number of calories your body burns in a day, combining resting metabolism, digestion, everyday movement, and exercise.
  • Appetite suppression · A reduction in the drive or desire to eat, distinct from the fullness felt during or after a meal.
  • BMI · Body mass index: a weight-to-height ratio commonly used as a screening threshold for obesity and GLP-1 eligibility.
  • Tirzepatide · A once-weekly dual GIP and GLP-1 receptor agonist made by Eli Lilly, marketed as Mounjaro for type 2 diabetes and Zepbound for weight management and obstructive sleep apnea.

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