I wouldn't replace lunch with a protein shake, but I do think protein shakes can have a place in an overall meal plan.
My protein shakes give me about 25 grams of protein for not very many calories. But they do not fill me up. They help me reach my protein goals (I lift weights).
My goal is to not be hungry and if all I had for lunch was a protein shake, I would be STARVING! Today my lunch was a steak sandwich with avocado and onion and asparagus. Now that's a lunch!
Volumetrics is the principle of eating foods that will fill you up without totally killing you calorie wise. Think fruits and veggies. Whole grains! Beans! It is possible to eat a large quantity of healthy food and lose weight.
What I would suggest first is just spend a week logging all your food in an online counter such as the Daily Plate. Once you see where you are, you can see where you need to go.
It appears that for most folks, a modest calorie restriction will facilitate weight loss. We all do things a little differently. And don't think you need to have all of the answers right out of the gate. I started out calorie counting and running and now I eat 6 times a day, focusing on getting in enough protein, veggies, fruit, fat, and carbs. I'm now weight lifting and running, but that was an evolution.
What else do you eat? If you post a typical menu, I'm sure we could help! Do you exercise?
