How to shop like an adult -- even when you're not.

As millennials, we live in squalor for most of our 20s.

The one expense that can make or break your budget is food. And how you spend money on food determines how much savings you'll have left in the bank. Shopping while poor is an art learned by experience -- and by experience only. 

Here is what I've learned:

• Buy cheap staple foods -- foods that can be cooked multiple ways. That way, you have an endless variety of meals at your fingertips. And trust me -- you will appreciate that variety fast.
• Not to be understated is this one key component of eating while poor: if you want to save money, learn to cook. Seriously. Google it. You don't have to make elaborate meals, either. You can make simple, nutritious meals on a budget from minimal ingredients. Make sure to eat staple nutritious foods. When you're living on your own, it's not always easy to manage money. Nutrient deficiencies can totally happen. It won't feel good. You're an adult now. Self-care is an art, not a science.

These are the best staple foods you should always have in your fridge and/or cabinet.

1. Eggs.

Eggs are filling -- and delicious. You can cook eggs a million different ways.

They've got protein, fats, and omega-3s. Eggs will also kill your appetite and feed your brain. I am strongly convinced that eggs in tortillas are the perfect breakfast.

2. Tortillas.

You will notice that on this list there are no snack foods. Every food item on this list requires the act of actually preparing a meal. You will start to crave carbs, fast. You will see tortillas in your fridge, and that will motivate you to make eggs.

If you can splurge for it, invest in shredded cheese. Shredded cheese means tortillas have double-potential -- you can make egg wraps- OR cheese quesadillas.

Cheese quesadillas feel really unhealthy, but they aren't. Cheap and sustainable.

3. Salad.

Since you're cutting out snack food, you'll want something in your fridge that's readily consumable. Salad is that food. Salad is also hella filling. And it's hella cheap.

Plus you need vegetables. Invest in salad.

4. Potatoes.

Potatoes are hands-down the single most important food. Pop them in the microwave baked, slice them into baked chips for the oven, or mash them -- potatoes are filling, nutritious, and consistently enjoyable.

Potatoes are fantastic with butter alone, but if you want to splurge and shake things up, invest in gravy.

No one ever told you this, but microwaved potatoes covered in gravy are even better than potatoes mashed. Trust me -- also cheap.

They're also packed with vitamins and iron -- which, on a cheap budget, you will badly need.

5. Pasta.

Pasta is filling -- and endlessly delicious. Pasta is also very cheap.

Pasta pretty much sells itself. It's the most delicious carb.

That is pasta.

6. Frozen Vegetables or Beans.

Cheap, filling, and dude, you need to be eating vegetables. Add some color and variety to your diet. You will feel hydrated and better, overall. Drown them in butter if you hate them. Regardless: frozen vegetables.

7. Butter.

Butter makes any staple food into a meal. You will need butter -- and lots of it. Don't cut corners and skip out on it -- It's the butter that makes food taste more filling. Butter is a must.

Extra Credit: Box Wine.

Okay, so this is not a food item. But if you are an adult (which you are) and if you are a drinker (let's be real), and if you're on a limited budget, then it's time to admit that bottled alcohol is a thing of the past.

I know you love your craft beer and your Apothic Red. But splurging on alcohol will drain your wallet. A box of wine is about $15, and it's the equivalent of three huge bottles. If you're a regular drinker, this is an adjustment that's simply realistic.

I know this doesn't sound fun, but trust me -- things are not as grim as they sound. Food is amazing, and you CAN sustain your nutrition on a budget. I believe in you. And you'll love it when you have the extra money to spare. Good luck, and happy eating!

What's your favorite delicious food that won't break the bank? Share your insights in the comments.