Identifying food sources that contain zero carbs and zero sugar can be challenging because most natural foods contain at least trace amounts of carbohydrates or naturally occurring sugars. However, there are several low-carb and low-sugar foods that are considered highly nutritious and beneficial for health. Here’s a list of 15 such foods that are very low in carbs and sugar:

1. Salmon: Rich in protein and healthy fats, salmon is a nutritious choice with negligible carbs and sugar.
2. Tuna: Another excellent source of protein and omega-3 fatty acids, canned or fresh tuna is low in carbs and sugar.
3. Sardines: Like tuna, sardines are a good source of protein and healthy fats, and they are very low in carbs and sugar.
4. Shrimp: Low in calories and carbs, shrimp is a great seafood option with no sugar.
5. Chicken Breast: A lean protein source that is virtually carb-free and sugar-free.
6. Turkey Breast: Similar to chicken breast, turkey breast is low in carbs and sugar while being high in protein.
7. Beef (Grass-fed): Lean cuts of grass-fed beef provide protein and essential nutrients with minimal carbs and sugar.
8. Pork Tenderloin: Another lean meat choice that is low in carbs and sugar.
9. Eggs: Eggs are a complete protein source and contain almost no carbs or sugar.
10. Spinach: A highly nutritious leafy green vegetable that is very low in carbs and sugar.
11. Broccoli: Rich in vitamins, minerals, and fiber, broccoli is low in carbs and sugar.
12. Cauliflower: A versatile vegetable that can be used in various dishes and is low in carbs and sugar.
13. Avocado: A fruit that is high in healthy fats and fiber, avocados are low in carbs and sugar.
14. Olives: Whether black or green, olives are a low-carb and low-sugar snack option.
15. Coconut Oil: A source of healthy fats that contains no carbs or sugar.

These food options can be incorporated into a low-carb or ketogenic diet, offering essential nutrients without contributing to carb or sugar intake.