If you want to influence your weight, you need to control your calories. If you want to influence your health, you need to control your nutrition.
There are many ways to accomplish both of these.
One way is portion control.
When you are focusing on portion control, you are splitting your plate up into segments and filling each one with certain groups. You are making sure that you are including certain portions of certain foods each time you eat.
The end goal with this, and any other diet (or "eating style" for those anti-dieters out there) is to increase mindfulness to help control both quantity and quality of your food.
With portion control, you are looking to be mindful, without stressing the details of exact calories or macronutrients. At each meal, you are looking in include a serving of protein, fruits/veggies and some carbs (optional).
Here are some examples of how you might set up you plate. If you were looking to lose/maintain weight something like this would be a good place to start.
The carb source is optional, but could easily be subbed out for some more protein, fruits or veggies.
If you were looking to gain some weight or were looking to maintain performance, this might be a better option:
As with all of your eating, the more often you can fill this plate up with high quality, single-ingredient, whole food the better. However, sometimes your carb serving may just need to be cake - enjoy!
You may be looking at the plate wondering where the serving of fat is. Realistically, most people don't need to worry about adding a lot of fat to their diet. Your protein source will probably have some and your carbs/veggies will more often than not have some sort of fat on them. If you are falling short on your fat goals, the hand method will help (below).
The portion control method is great for people who are often on the go. Trying to count calories while on the road can be next to impossible. Instead of being exact in your grams of protein you are just looking to fill up a quarter of your plate with whatever protein is available.
Along with the plate strategy, there is another method you could try with portion control. It's the hand method. The hand method uses different parts of your hand to act as a serving size guide for different food groups.
For example, your protein source is roughly the same size as your palm. Your fruit/veggie serving is the size of a fist, a serving of carbs is roughly the size of half a fist and a serving of fat is the size of your thumb. This looks like this:
This approach is great because it's scalable to your body- if you are a bigger person, you will probably need bigger portion sizes.
With this approach, it can be very easy to overthink it. Foods that are blended (like eggs, nuts, dairy products, etc.) can be tough to place. Here is a simple cheat sheet to help you know where those go:
Remember, our goal is to be reasonable eaters, not perfect. If you happen to call a whole egg a serving of protein instead of fat, don't sweat it. Being consistently "good enough" is far better than being rarely "perfect".
Personally, if I am using the hand method I count foods as a serving of what they have the most of. While nuts do have protein, they are mostly fat - thumb-sized. With eggs, I may consider it a serving of protein and my fat serving. Beans and lentils may be a protein serving for the plant-based eaters out there, but a carb for omnivores. Figure out what works for you.
Individualizing this approach goes like this:
Men, start with 1.5-2 servings of each at each meal.
Women, aim for around 1-1.5 of each.
If this is going to work well (like any diet), you want to be consistent. If you want to know your sweet spot for the number of servings, you need to know how your body reacts to them. If you are eating two servings of each, then one serving of each, then five servings of carbs for a few days, it becomes difficult to make adjustments. If you are getting your 1-2 servings of each every day and your weight is going up, you could try dialling a serving of carbs back a bit. If you weight is going down too quickly (yes, that's a thing) or it's not going up when you want it to, you could try to add another .5-1 serving to a few meals each day.
What about snacks?
For both the plate or hand method, try to pick snacks from the protein and/or fruit and veggie groups as much as possible. A simple measurement tool is that your snack must fit in the palm of your hand. That should be enough to get you through to the next meal. If you find that you are constantly craving and hungry between meals, you can either wait it out (it's probably just cravings) or add a little bit more protein to your meals.
Just like calorie counting, portion control is a tool. There is nothing holy or magical about it. It's just another way that you can increase mindfulness with your eating.