The most successful and sustainable weight loss I have observed looked like this:
Breakfast: one single serving of plain Greek yogurt and two cups of black coffee.
Lunch: grilled chicken (breasts/thighs/chicken burger), or BBQd pork chop (cooking method, not BBQ sauce), or left over steak slices. Paired with a large serving of vegetables, usually roasted Brussels sprouts, broccoli, cauliflower, or asparagus. Sometimes lettuce wraps or a baked potato with salsa and black beans for variety. Generally this was the largest meal.
Dinner: Similar to lunch, just picking something different than whatever protein and veggies they had for lunch. Sometimes ordering in but following similar guidelines (protein and veg heavy, no fatty sauces, cheese, or breads).
Snacks: a large carrot, one string cheese, small scoop of cottage cheese, handful of nuts. Only one snack per day (two if really hungry/struggling with the diet).
Condiments: Lots of hot sauce, mustard, pepper, balsamic vinegar, everything bagel seasoning, and chopped chilis. Moderate olive oil and salt and low fat mayo. This person doesn't like citrus, but I think lemon or lime juice is so good on roasted vegetables.
Etc: no alcohol during the week. Less disciplined eating on the weekend, but still mindful and tracking calories. For example, picking a grilled chicken on wheat sandwich with no cheese or mayo instead of a double cheeseburger when out for lunch. Drinking on the weekend allowed, but more moderately than before.
Water: after morning coffee, lots of large Mason jars of ice water. Putting the water in a fun container helped for some reason.
Activity: More than before, but not extreme. One 20-30 minute Peleton ride or 3 mile walk or 60 minute bike (beach cruiser style bike, so not intense) ride every other day.
I personally couldn't stick to this, but it was impressive to see and very effective. It required discipline and accepting the boredom of a certain rotation of meals, but the weight fell off without being ravenous or needing to binge out of feeling deprived since the weekends were more relaxed, food-wise.