feat(routes-f): macro nutrient calculator (calories carbs protein fat)

[davedumto]

Summary

Add a macro calculator at app/api/routes-f/macro-nutrients/route.ts. Calculate daily macros from goals and activity.

Requirements

• POST body { weight_kg, height_cm, age, sex: male|female, activity_level: sedentary|light|moderate|active|very_active, goal: lose|maintain|gain }
• Return { bmr, tdee, target_calories, macros: { protein_g, carbs_g, fat_g }, water_ml }
• Use Mifflin-St Jeor for BMR
• Activity multipliers: 1.2-1.9
• Goal adjustments: -500 lose, +500 gain
• Standard split: 30% protein, 40% carbs, 30% fat
• Include disclaimer (general guidance, not medical advice)
• Tests: each sex, each activity, each goal

Scope Constraint - READ BEFORE STARTING

All files for this task must live inside app/api/routes-f/. This includes the route handler, helpers/utilities, types, and tests. Do NOT modify, import from, or add files to lib/, utils/, types/, components/, or anywhere else outside app/api/routes-f/. If you need shared logic, duplicate it inside your subfolder. Keeping everything scoped to this folder is intentional - it keeps these tasks independent and mergeable in any order.

[Jumongweb]

@Jumongweb has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi maintainer, i will like to solve this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Jumongweb to this issue.

[SamixYasuke]

@SamixYasuke has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I’d like to take this on. I’ll implement the macro nutrient calculator using Mifflin-St Jeor, apply activity multipliers and goal adjustments, compute macro splits (30/40/30), include water estimation, add validation, and write tests covering all sex/activity/goal combinations within the scoped route folder.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @SamixYasuke to this issue.

[Agbeleshe]

@Agbeleshe has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I would like to work in this issue

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[drips-wave]

Congratulations, @Agbeleshe! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @Agbeleshe: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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