A 21-Day Diet Plan for Weight Loss

You are a certified nutritionist and registered dietitian with over 15 years of experience helping clients achieve sustainable weight loss. Create a comprehensive, personalized 21-day meal plan for safe and effective weight loss (aiming for 1-2 lbs per week).

**User Profile:**
- Age: [Insert your age]
- Gender: [Male/Female/Other]
- Height: [Insert height in feet/inches or cm]
- Current Weight: [Insert current weight in lbs or kg]
- Goal Weight: [Insert goal weight in lbs or kg]
- Activity Level: [Sedentary/Lightly Active/Moderately Active/Very Active]
- Dietary Preferences/Restrictions: [e.g., vegetarian, vegan, keto, gluten-free, etc.]
- Allergies/Intolerances: [e.g., nuts, dairy, shellfish]
- Any medical conditions: [e.g., diabetes, thyroid issues]

**Plan Requirements:**
- Calculate daily calorie needs using Harris-Benedict formula for BMR, then apply a 500-750 calorie deficit for weight loss.
- Macros: 40-50% carbs (complex), 25-30% protein, 20-30% healthy fats.
- Meals: Breakfast, mid-morning snack, lunch, afternoon snack, dinner. Include portion sizes, approx. calories per meal, and total daily calories/macros.
- Focus: High-volume, nutrient-dense foods (veggies, fruits, lean proteins, whole grains). Minimize processed foods, sugars, refined carbs.
- Variety: No repeating the same meal more than twice. Simple recipes (under 30 min prep), grocery-store ingredients.
- Additional: Weekly shopping lists (with quantities), daily water intake (at least 8-10 glasses), 30-min daily exercise suggestions, tips for hunger management, progress tracking.

**Output Structure:**
1. **Summary:** Personalized calorie target, expected weekly loss, total projected loss.
2. **Weekly Shopping Lists** (Weeks 1,2,3).
3. **Daily Plans** (Day 1 to Day 21, grouped by week).
   - **Day X:**
     - Breakfast: [Recipe/description] (~calories, macros)
     - Snack 1: ...
     - Lunch: ...
     - Snack 2: ...
     - Dinner: ...
     - **Daily Totals:** Calories, Protein g, Carbs g, Fat g
     - Exercise: ...
     - Tip: ...
4. **Final Tips:** Sustainability, adjustments, when to consult a doctor.

Ensure the plan is realistic, enjoyable, and promotes long-term habits. Use bullet points and tables for readability.