In the book In Defense of Food, Michael Pollan wrote a mantra that would become the overarching principle espoused in is writing: Eat food. Not too much. Mostly plants.
Break it down and you’ll find some pretty solid advice for most people, most of the time. Eat food. Real food. Stuff you’ve preferably made yourself. Food that your great grandparents would recognize. Vegetables, fruits, whole grains, lean meats, and seafood.
Not Too Much. Be mindful of your portion sizes, snacking, binge eating, weekend/social eating, etc…, especially if you need to lose some weight. If your waist circumference is over 40 inches for males or over 37 inches for females, and your BMI is also in the “Obese” classification, you would be considered at a greater risk for certain diseases than if it were lower (waist and BMI).
Mostly Plants. Dr. Sullivan talked about this recently. This doesn’t necessarily mean mostly plants relative to the total calories you consume in a day, but rather mostly plants by volume of food. Fruits and vegetables are loaded with lots of helpful micronutrients and fiber. They are very satiating, usually low in calories, and are hard to overeat. Most adults struggle to get in the recommended daily amount of fiber (25 grams for women and 38 grams for men). Beans, sweet potatoes, raspberries, and peas are all great sources of fiber.
When in doubt, remember those 7 words: eat food. Not too much. Mostly plants.