The Nutrition Facts panel looks like a wall of numbers, but the FDA designed it so that everything you need to make a quick decision lives in the same place [1]. Most of it boils down to seven things:
1. Serving size — read this FIRST. Everything below is per serving, and serving sizes are often smaller than what you'd actually eat in one sitting. The FDA updated serving sizes in 2016 to better reflect real consumption [1].
2. Calories — total energy. Context-dependent. 200 calories is a lot for a snack but tiny for a meal.
3. Saturated fat — the AHA recommends limiting saturated fat to less than 6% of daily calories (about 13g/day on a 2,000-calorie diet), with the FDA's Daily Value set at 20g [2].
4. Sodium — the USDA Dietary Guidelines recommend less than 2,300mg/day for most adults [3]. Most processed food hides a lot of sodium here.
5. Added sugars (the indented line under Total Sugars) — the FDA Daily Value is 50g/day, the AHA recommends even less (25g/day for women, 36g/day for men) [2].
6. Fiber — the USDA recommends about 25g/day for women, 38g/day for men [3].
7. Protein — varies by person, but check whether the protein number makes sense for the food. A 'protein bar' with 4g of protein is mostly marketing.
The % Daily Values are based on a 2,000-calorie diet, which may or may not be you, so use them as a rough guide, not gospel. As a quick rule: 5% DV or less is 'low', 20% DV or more is 'high' [1].