The simplest diet that covers all your nutritional bases is built from roughly five to seven whole foods, chosen so their strengths overlap and their gaps cancel out. No single food can keep you healthy indefinitely, but a small, deliberate combination can. The key is pairing foods that complete each other’s missing nutrients, particularly protein building blocks, essential fats, and the handful of vitamins that only show up in specific places.
Why No Single Food Is Enough
Your body needs two types of fat it cannot manufacture on its own (omega-3 and omega-6), around nine amino acids it can only get from food, more than a dozen vitamins, and several minerals. Adults need about 1.1 to 1.6 grams of omega-3 fat per day, at least 3,510 mg of potassium, and a bare minimum of 8 to 10 mg of vitamin C just to avoid scurvy. Skip any one of these long enough and specific problems emerge. Without vitamin C, for example, scurvy symptoms start appearing within 60 to 90 days. Without vitamin B12, your body can draw on liver stores for several years before deficiency sets in, but when it does, the nerve damage can be permanent.
Potatoes often come up as the closest thing to a one-food diet. They’re rich in potassium, vitamin C, and decent starch energy. But a cardiovascular dietitian at the University of Virginia pointed out that surviving and being healthy are two very different things. People who have attempted potato-only diets show visible muscle wasting within months because potatoes lack sufficient protein, fat, and several key vitamins. Adding butter helps with calories but floods you with saturated fat while still leaving major gaps in B12, vitamin A, iron, and essential fatty acids.
Rice and Beans: The Classic Foundation
Rice and beans together form what nutritionists call a complete protein. Each one is missing certain essential amino acids that the other provides, so when eaten together, you get all eight amino acids your body cannot make on its own. This pairing has fed civilizations for thousands of years and remains one of the cheapest, most shelf-stable food combinations available.
Where rice and beans fall short is in fat-soluble vitamins (A, D, E, K), vitamin C, vitamin B12, calcium, and essential fats. They also provide very little of the omega-3 fatty acid your body needs daily. So while rice and beans are an excellent starting point, you need a few more items to close the gaps.
A Practical Minimal Diet
Here’s what a nutritionally complete simple diet looks like, built from the fewest possible foods:
- Rice and beans (or lentils): Your calorie base and complete protein source. Brown rice adds more B vitamins and fiber than white.
- Dark leafy greens (spinach, kale, or collards): These supply vitamin A, vitamin C, vitamin K, calcium, iron, folate, and magnesium. A daily portion of greens covers most of the micronutrient gaps that grains and legumes miss.
- Eggs: One of the most nutrient-dense foods available. Eggs provide B12, vitamin D, vitamin A, choline, complete protein, and both omega-3 and omega-6 fatty acids. Two eggs a day fill several of the hardest gaps to cover on a plant-only diet.
- A small amount of oil or fat: A tablespoon of flaxseed oil or canola oil daily covers your omega-3 requirement. Olive oil works for cooking but is lower in omega-3s.
- A piece of fruit: An orange, a banana, or a handful of berries provides additional vitamin C and potassium as a buffer.
That’s five to six items. You could eat variations of this every day and meet your body’s requirements for protein, essential fats, all major vitamins, and the critical electrolytes. It’s not exciting, but it works.
What Each Addition Fixes
The logic behind this list is gap-filling. Rice and beans handle calories and protein but are missing B12, which only reliably comes from animal products or fortified foods. Eggs solve that. Greens handle vitamin C, which prevents scurvy, along with vitamin K for blood clotting and calcium for bones. The oil handles essential fatty acids that grains and legumes barely contain. Fruit adds an extra margin of vitamin C and potassium beyond what greens provide.
If you removed eggs from this list, you’d need either a B12 supplement or a fortified food like nutritional yeast. B12 is the one nutrient that essentially does not exist in unfortified plant foods. Your liver stores enough B12 to last a few years, so deficiency wouldn’t be obvious right away, but it would catch up with you.
The Cost of Too Little Variety
A simple diet can meet your basic nutrient needs, but eating a narrow range of foods does come with trade-offs. Research from the American Gut Project found that people who ate 30 or more different plants per week had significantly higher gut microbiome diversity than those eating fewer than 10. That diversity matters because gut bacteria produce short-chain fatty acids and other compounds linked to immune function, inflammation control, and metabolic health. Interestingly, the variety of plants mattered more than whether someone identified as vegan, vegetarian, or omnivore.
This doesn’t mean a simple diet will make you sick. It means that if you’re eating the same five foods every day for months, your gut bacteria community narrows, and your resilience to illness and digestive problems may decrease over time. Even small additions, like rotating between different types of beans, switching up your greens, or throwing in a sweet potato instead of rice once a week, help maintain that bacterial diversity without adding complexity.
How to Make It Even Simpler
If meal planning and cooking feel like the real barrier, these strategies strip things down further:
- Batch cook once a week. A large pot of rice and beans, portioned into containers, gives you a ready-made base for every meal. Reheat and add greens or an egg.
- Canned beans work fine. They’re nutritionally comparable to dried beans and take zero prep time.
- Frozen greens are equivalent to fresh. A bag of frozen spinach stirred into hot rice and beans delivers the same vitamins without wilting in your fridge.
- Hard-boiled eggs keep for a week. Cook a dozen on Sunday and grab two a day.
The total cost of this diet runs remarkably low. Rice, dried beans, frozen greens, eggs, a bottle of oil, and a few pieces of fruit can feed one person for well under $30 to $40 a week in most areas, making it one of the most affordable nutritionally complete diets possible.
When a Supplement Makes Sense
If you want to go fully plant-based or just can’t tolerate eggs, a basic multivitamin or a standalone B12 supplement closes the biggest remaining gap. Adults need about 2.4 micrograms of B12 daily. A simple daily supplement handles this and removes the need to plan around animal products entirely. Vitamin D is the other common shortfall, especially if you get limited sun exposure, and most multivitamins include it.
Beyond that, the foods listed above cover your needs without supplementation. The goal of the simplest livable diet isn’t perfection. It’s building a small, sustainable routine from a handful of affordable, accessible foods that keep your body functioning well over the long term.