Understanding calorie needs can be more complicated for transgender and non-binary individuals. This article explains how Kanvie approaches this topic responsibly.

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Background

Common BMR calorie formulas including our default, Mifflin-St Jeor, were developed using large population studies and include a biological sex term because, on average:

• People with testosterone-dominant hormone profiles tend to have more lean mass, which raises BMR
• People with estrogen-dominant hormone profiles tend to have slightly lower lean mass at the same weight/height/age

The Mifflin-St Jeor formula itself cannot know your hormone profile or muscle-to-fat ratio. It can only use population averages. This is why biological sex is included mathematically.

This means that, for accurate calorie budgeting, formulas must use the physiological inputs they were designed for, which in this case includes your biological sex.

However, this creates a practical question:

How do you get an accurate daily calorie budget when your body, hormone profile, or muscle mass doesn't neatly match one of these traditional groups?

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How Kanvie Approaches This

Kanvie offers two complementary options:

1. You control your biological sex input

The Mifflin-St Jeor formula, which is the default, requires a biological sex input. Kanvie does not infer or assume this value.

Learn more about editing your biological sex in the Kanvie app here.

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2. You control which BMR formula is used

Since different formulas rely on different assumptions, you can choose the method that best fits your body:

• Mifflin–St Jeor (default)
• Katch–McArdle (recommended when body-fat % is known)
• Cunningham (advanced, also requires your body-fat %, for athletic or highly trained individuals)

Learn more

• Compare the three different calorie formulas supported by Kanvie
• Editing your basal metabolic rate formula in the Kanvie app

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Choosing a BMR Biological Sex Input

If you use the default settings of your Kanvie app, the Mifflin-St Jeor formula will be used. This means that your biological sex input from your biometric data settings will be used for calculating your daily calorie budget.

If you are pre-HRT

Your metabolism likely aligns more closely with the formula for your biological sex as assigned at birth, because:

• Muscle mass, bone structure, and hormone balance are typically unchanged
• Population-based formulas reflect that physiology

If you are on gender-affirming hormone therapy (HRT)

HRT can shift body composition in ways that affect BMR:

Trans men (masculinizing HRT)

• Muscle mass generally increases
• Fat distribution changes
• BMR tends to rise toward the male-average range

→ You may find the male formula more accurate after several months on testosterone.

Trans women (feminizing HRT)

• Lean body mass usually decreases
• Fat distribution shifts
• BMR tends to lower toward the female-average range

→ You may find the female formula more accurate after several months on estrogen + anti-androgens.

If you are non-binary

BMR equations require choosing one of the two physiological categories used in the original research.

→ You can select the biological sex option that best matches your current physiology (e.g., muscle mass, fat distribution, hormone profile). Your choice can be updated at any time as your body changes.

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If You Track Body Fat % Regularly

If you are able to provide regular measurements of your body fat percentage, we always recommend using the Katch-McArdle formula or the Cunningham formula.

Learn more

• BMR formulas you can use with the Kanvie app
• Editing your basal metabolic rate formula in the Kanvie app
• Tracking your body fat percentage with the Kanvie app
• Reading your body fat percentage or weight from Apple Health or Health Connect