## TL;DR

Nutrition provides the energy and nutrients necessary for health. Macronutrients: carbohydrates (4 cal/g, energy), proteins (4 cal/g, repair/build), fats (9 cal/g, hormone production, cell membranes). Micronutrients: vitamins and minerals needed in small amounts. Water: essential for all bodily functions. Balance, variety, moderation are key principles.

## Core Explanation

Carbohydrates: simple (sugar, quick energy) vs. complex (whole grains, sustained). Proteins: complete (animal, contains all essential amino acids) vs. incomplete (most plants). Fats: unsaturated (olive oil, nuts — heart-healthy), saturated (limit), trans (avoid — artificial, banned US 2021). Fiber: 25-30g/day for digestion and heart health. MyPlate: half vegetables/fruits, quarter protein, quarter grains.

## Further Reading

- [Dietary Guidelines for Americans 2020-2025](https://www.dietaryguidelines.gov/)