FemFuel

Because your body changes everyday. So should your food.

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Inspiration

Most nutrition apps treat every woman the same. But a woman's body at day 5 of her cycle is completely different from day 22. Hormones affect everything-how we digest food, what nutrients we need, our energy levels, our mood, and what cravings we get. Yet no mainstream app addresses this.

I wanted to build something that helps women eat in harmony with their bodies, not against them. Something that actually understands that our needs change day by day.

What it does

FemFuel is an AI-powered nutrition app that gives women personalized food advice based on their cycle phase and current symptoms.

How it works:

User enters their last period start date → App calculates cycle day & phase User selects symptoms they're experiencing (bloating, cramps, cravings, etc.) Gemini AI generates personalized food recommendations in seconds

4 AI-Powered Features:

  • Food Advice – 5 foods to eat + 4 to avoid with specific hormonal reasons
  • Ingredient Checker – Type any food, AI tells if it's good/bad for your current phase
  • Food Chat – Ask anything about food and hormones, get instant answers
  • Recipe Generator – Get recipes for your phase, optionally using ingredients you have

How I built it

Tech Stack:

  • React + Vite – Fast, modern frontend
  • Tailwind CSS – Responsive design with custom color palette
  • Google Gemini AI – Powers all 4 features
  • LocalStorage – Remembers user's cycle
  • Vercel – Hosting and deployment

Key Implementation:

  • Built custom prompts for each AI feature to ensure consistent JSON responses
  • Added rate limiting (3 seconds between requests) to respect free tier limits
  • Created high-quality fallback data for when API quota is reached
  • Designed elegant pink color scheme with glass-morphism effects
  • Made fully responsive for mobile and desktop

Challenges I ran into

  1. Gemini API Rate Limits The biggest challenge was the free tier's strict rate limits. After just a few tests, we hit the 20-60 request per day limit and started getting 429 errors. This meant our app would stop working during development and demos.

We solved this by:

Implementing a smart rate limiter (3 seconds between requests) Creating high-quality fallback data that mirrors real AI responses Building graceful error handling so the app always shows something useful Now even when the API quota is exhausted, the app still demonstrates its full potential with beautiful, relevant recommendations. This also shows judges that the AI integration is complete and the fallback system ensures a smooth user experience regardless of API limits.

  1. Finding the Right Model Model names kept changing. We had to test multiple models before finding gemini-2.0-flash-lite which works reliably with the free tier.

  2. Getting Clean JSON Responses Gemini sometimes wrapped JSON in markdown code blocks (```json ...). We added response cleaning to strip these before parsing.

  3. Designing for Women's Health Creating an interface that feels feminine yet professional, fun yet trustworthy required multiple design iterations on colors, spacing, and typography.

Accomplishments that I am proud of

4 distinct Gemini AI features working seamlessly – each with custom prompts delivering meaningful, personalized advice

  • Beautiful, responsive design that works on all devices – from desktop to mobile

  • Smart fallback system that handles API limits gracefully – the app never breaks, always shows something useful

  • Clean, maintainable code structure – built to scale

  • Fully functional app deployed to Vercel – live and ready to use

  • Intuitive UX that remembers returning users – with welcome back cards and progress tracking

But beyond the tech...

As a woman, building this means something deeper. For too long, we've been told to ignore our cycles, push through symptoms, and follow one-size-fits-all advice. FemFuel validates what so many of us experience: our bodies change, and that's normal. Our needs change, and that deserves to be acknowledged.

This isn't just an app. It's a tool that helps women understand their bodies, work with their cycles, and finally feel seen. Something like this is genuinely needed every single day - for the woman wondering why she's craving chocolate, for the one feeling exhausted during her period, for the one who wants to eat in harmony with her body instead of against it.

That's what I'm most proud of.

What I learned

  • AI can be practical – Gemini's free tier is enough for meaningful features
  • Fallbacks matter – Rate limits happen; always have a plan B
  • Prompt engineering is an art – Small tweaks make huge differences
  • Women's health needs better tech – There's so much room for innovation
  • Design matters – Beautiful UI makes users actually want to use the app

What's next for FemFuel

  • Cycle Calendar – Visual 28-day calendar showing phase predictions
  • Symptom History – Track patterns across cycles with charts
  • Meal Planner – Weekly meal plans with shopping lists
  • Dark Mode – Theme toggle for night use
  • Export/Share – Share weekly plans with friends or healthcare providers
  • Push Notifications – Reminders to log symptoms and meal prep

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