If you’ve heard someone talking about their macros (a.k.a. macronutrients), you probably understand that it has something to do with carbs, protein, and fat—but what exactly does it all mean?

A lot, actually. Developing a daily macros ratio can help you achieve your personal fitness and health goals.

What Are Macros?

Macronutrients are molecules our bodies use to create energy. In simpler terms, they are the types of foods (carbs, fats, and protein) we need to eat each day in large amounts, according to the National Institutes of Health. (Micronutrients are vitamins, minerals, and amino acids).

But what macronutrient ratios should you follow? The experts weigh in below.

The Right Macronutrient Ratio for Weight Loss

There are plenty of weight-loss plans, and most involve creating a calorie deficit. It’s pretty simple: To shed the pounds, you need to burn more calories than you take in each day. Counting macros is no different, but before you start adjusting your ratio, you’ll need to determine your ideal calorie intake based on your goals.

You can calculate how many calories you should consume each day using the Mifflin – St Jeor equation, which takes your weight, height, age, activity level, and desired weight loss or gain into consideration before spitting out a daily calorie number. Once you have that number, you will also need to adjust each macronutrient. Just know that there’s no magic, one-size-fits-all ratio for any goal, since it’s so individual.

Related: What Is The “If It Fits Your Macros” Diet—And Should You Try It?

So, how does counting macros differ from simply counting calories? Your macronutrient goal focuses on the type of calories you eat, not just the total amount. If your goal is to drop weight, cutting back on your carbohydrate intake should be your main focus, according to registered nutritionist Amy Shapiro of Real Nutrition NYC.

“It’s mostly scaling back on those simple carbohydrates and sugar,” says Shapiro. “We want to bring down the carbohydrates to lose weight and increase the fat and protein to help keep you full and keep your muscles supported.”

FYI: This ratio doesn’t mean you can just eat red meat all day. Shapiro urges the importance of paying attention to portion sizes, eating a balanced meal that includes fruits, vegetables, and whole grains, and staying within your set calorie limit for the day.

In general, the Dietary Guidelines for Americans suggest that 45 to 65 percent of our total daily calorie intake come from carbohydrates (while 10-35 percent come from protein and 20-35 percent from fat).

Related: 5 Fitness Apps That Helped Me Drop—And Keep Off—75 Pounds

By dropping that percentage closer to the lower end or below 45 percent and making sure that the carbohydrates consumed are complex carbohydrates like veggies and whole grains (rather than processed carbs), you can expedite your weight loss. Lean proteins (like turkey, eggs, or beans) and heart-healthy fats (like olive oil and avocado) are also excellent for weight loss.

Some people up the ante on their fat intake by ascribing to the ketogenic diet, which plays with the ratio to focus on a very high-fat, low-carb diet. Basically, its goal is to get you into ketosis, a specific metabolic state which forces our bodies to begin running on ketones, which burns fat. How do you achieve this state? By getting less than 10 percent of your calories from carbs. On a ketogenic diet, you’ll get about 75 percent of your calories from fat and about 20 percent from protein for several weeks.

The Right Macronutrient Ratio for Building Muscle

If you’re looking to gain muscle, your macronutrient ratio will differ pretty drastically from someone trying to lose weight.

“In order to put on muscle, what we focus on is protein,” Shapiro says. “Protein breaks down into amino acids, [which are] the building blocks of muscle.”

Related: Shop protein powder to help you pack on the muscle.

Again, you’ll stay on target with your daily calorie goal, but you’ll increase your protein intake to between one and 1.5 grams of protein per pound of body weight (so, 1.5 grams per every pound for a 180-pound person amounts to about 270 grams of protein daily). Protein is the name of the game here, but it’s definitely not a free-for-all!

“When you eat too much of anything that you’re not using, you store it as fat,” Shapiro says. “It’s starts to tax your body when you have to break down and eliminate the byproducts of protein. The research isn’t behind it that more than 1.5 grams is going to actually help you to put on significant muscle.” So it’s key that you stay on target.

In order to build muscle, we need to burn energy, and—you know it—energy comes from carbs. So once you’ve established your protein intake, fill out your macro ratio with roughly 40 percent of your calories coming from healthy carbohydrates. The rest will come from heart-healthy fats.