“Are you tracking your macros?” This fairly common question among health aficionados today may not have made sense to nutrition-savvy people of the past. Macros, short for macronutrients, are the building blocks of any diet. Break down any food into its basic molecular components and you’ll find the proteins, fats and carbohydrates that give us the energy to live. And it’s become increasingly common to pay close attention to what proportions of each you eat, whether your goal is weight loss, muscle building, decreased hunger or just improving general health.

Proteins

Your body uses protein to build and repair muscles, organs and other tissues in your body. So even if you’re not working on your bulging biceps, you need plenty of protein in your diet to keep your body functioning. For instance, hemoglobin — the molecule that allows your red blood cells to shuttle oxygen around the body — is a protein. Proteins are also important for building components of your immune system, hormones, neurotransmitters and many structures inside each of your cells.

Proteins are made of different combinations of amino acids. The body can make many amino acids itself, but there are nine amino acids that you can only get from your diet — these are called the essential amino acids. People eating a diet that includes animal protein typically have no problem getting them all, but vegans and vegetarians need to be sure to consume protein-rich foods like beans, nuts and seeds to meet their protein requirements.

The current recommended daily allowance for protein is 0.8 grams per kilogram of body weight. That’s about 73 grams for a 200-pound person. Though, studies have suggested that that’s more of a minimum for a healthy diet. The jury’s still out on what the upper threshold for dietary protein is, though it’s known that excessive protein consumption can lead to kidney stones. That’s not to mention the side effects that come with eating too much of certain foods like red meat, which includes high cholesterol and heart disease.

Protein also triggers your body to feel full. A recent guide published in the British Journal of Diabetes explained that people will naturally want to continue to eat until they’ve gotten enough protein, which can lead to overeating when your meal is unbalanced. Their suggestion? Make sure your meal has 15 percent of its calories from protein — even if that means swapping a McDonald’s Big Mac meal (a burger, fries, and a drink) for two double cheeseburgers: You’ll almost double your protein for fewer calories and carbs.

Fats

Fats are still recovering from the undeserved bad reputation they had in the ’90s. More recent research has revealed that, perhaps counter-intuitively, it’s not necessarily fat-containing foods that make a person, well, fat. In fact, fats are a critical part of any balanced diet.

Fats come in two forms: saturated and unsaturated. The two come from different sources, and their chemical differences affect how you can cook with them and how they affect your health. Saturated fats come from animal products, and are more solid (picture: butter, cheese or lard). They’ve also been strongly linked to high cholesterol and increased risk of cardiovascular disease, which is why it’s recommended to limit them in your diet. Unsaturated fats, on the other hand, come from plants. This includes olive oil or the fats in nuts and avocados. These are considered healthy fats — your body needs them just like it needs proteins to build and repair. Every cell in your body has a membrane made of lipids, or fats. Body fat is also important for cushioning your internal organs and absorbing nutrients.

By the way: The saturated term refers to hydrogen atoms covering fat molecules. Both saturated and unsaturated fats have these atoms, but molecules of saturated fat are maxed out with as many hydrogens as their chemical formula can hold. This is also why the “hydrogenated oil” in your peanut butter is considered saturated fat, even though it comes from a plant source — it’s been chemically modified with hydrogens to make it that way. Although this may seem like a small difference in the chemical formula, it changes how the fat molecules behave in your bloodstream and whether they’ll raise or lower your cholesterol.

Carbohydrates

Carbs are the starches and sugars in our diet, and they give us energy. That’s because your body converts the carbohydrates you eat into glucose — your so-called blood sugar that powers your body’s cells and brain.  

The two types of carbs are simple and complex. Simple carbs are already in the form of sugar and are found in foods like honey, fruit and lactose-containing dairy products. Complex carbs are starches, like potatoes and grains. These are larger carbohydrate molecules and take your body longer to digest and therefore release glucose into your bloodstream more slowly.

Some people swear by carb-restricting diets as a strategy for weight loss, but researchers haven’t yet been able to confirm the long-term safety of eating this way — especially fully no-carb diets like keto. Although numerous theories exist on why this seems to work for some people, researchers do agree that it works when it causes people to eat fewer calories in an easy, sustainable way.

Micronutrients

Micronutrients are the vitamins and minerals your body needs to maintain good health. Six of the most essential micronutrients for health are iron, vitamin A, vitamin D, iodine, folate (vitamin B9) and zinc. They’re called “micro” because you need them in much smaller quantities than the macronutrients for your health — but that doesn’t make them less important. For instance, vitamin A deficiency can lead to blindness, while iron is essential for your hemoglobin to keep transporting oxygen around your body.

Although taking a multivitamin, in theory, is a good way to make sure you’re getting all your micronutrients — research has repeatedly shown that they don’t really work and that eating a balanced diet is a better way to get your vitamins and minerals.

But with fad diets on the rise, many people are opting to eat an explicitly not-balanced diet. A 2020 study in Food Science & Nutrition found that cohorts of people on high-fiber or low-carb diets were not getting enough micronutrients. Any time you cut something out of your diet, it’s important to be aware of what else you might be losing.

How Much Do You Need?

Dietary advice is tricky, since each person is so different. Researchers are constantly learning more about how different macro- and micronutrients affect our heath. If you’re looking for numbers, this online calculator gives you your macronutrient and micronutrient recommendations based on your height, weight, age, sex and activity level. But in the end, you’ll need to find a nutrition plan that’s right for you and approved by your doctor.