Eat a variety of non-starchy vegetables and low-sugar fruits such as these:
Salad Greens (lettuce, spinach, cabbage)
Other Leafy Greens1 (Swiss chard or other chard, collard greens, kale, bok choy)
Herbs (basil, parsley, cilantro)
Other salad vegetables (radishes, sprouts, cucumbers, tomatoes)
Other green vegetables (avocado, asparagus, broccoli, green beans, Brussels sprouts, okra, also cauliflower)
Other non-starchy vegetables (summer squashes, peppers, green onions, eggplant, artichokes, mushrooms)
If fruit allowed on your plan, servings of berries2 and melons and small peaches are good choices
Meat, Poultry, Fish, Seafood, Eggs
Almost any of these are fine. Eggs are extremely nutritious3. Oysters and liver have a little carb, so some diets recommend limiting them in the first phase.
Cream, butter, full-fat cottage cheese (see oils below for info on these), sour cream, cheeses, ricotta, sugar-free yogurt4
Fats and Oils
Most low-carb diet authors argue that foods high in saturated fats (butter, coconut oil) are not a problem in the context of low-carb diets, while a few others avoid them. Most say to avoid oils which are high in omega-6 fats (soy, corn, most safflower and sunflower). Partially hydrogenated oils should always be avoided.
Olive oil5 (particularly recommended)
High-mono safflower and sunflower oils (check the labels carefully) such as Saffola brand
Other oils in small amounts as flavoring (sesame and nut oils)
Other high-fat foods: nuts, nut butters, seeds, avocados, and cream
It’s a good idea to have frozen meats, fish, vegetables, and berries handy.
Canned versions of the above vegetables, also, black soy beans6, olives, coconut milk.
Nuts and Seeds
Most nuts and seeds (and butters made from them) are OK, although check the carbs. Flax7, almond8, and coconut flour/meal are particularly good for baking, but try to make sure they are fresh. Some diets avoid legumes, which include peanuts. Make sure coconut is unsweetened.
Mustard, full-fat mayo (preferably not made with soy oil), sugar-free ketchup, sugar-free salad dressings (hopefully not made with soy oil), soy sauce, pesto sauce, broth or bouillon, spices, hot sauce, sugar-free pickle relish, sugar-free jams9 and preserves
Unsweetened soy, almond, rice, or hemp milk
Unsweetened chocolate10 and cocoa powder
On a moderate-carb diet, you can add limited amounts of corn, al dente pasta, beans, high-fiber breads, and grains such as rice, quinoa, and barley. Also, more fruit.
Aisles to Avoid
Just Say No. Don’t go to these areas: Baked Goods, Cookies, Crackers, Bread, Candy, Pasta, Baking Supplies, and most processed foods.