If you’ve ever heard that carbs make you fat, protein shakes are the secret to strength, or that fat is the enemy of all, then it’s time to get something straight: Carbohydrates, proteins, and fats aren’t diet villains nor superheroes. They’re simply nutrients—specifically, macronutrients—that are necessary for all athletes to perform. So you need to eat all of them.

Maybe you’ve never even uttered the word “macronutrients” (also known as macros) when discussing your diet, but macros are the three essential dietary elements that you need in relatively large quantities just to live. By comparison, your body only needs trace amounts of micronutrients (hence the names).

Contrary to enormous amounts of hype and hysteria surrounding macronutrients (low fat! low carb! high protein!), you need all three to keep your human machine healthy and humming along on all cylinders.

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“All the macronutrients have fallen victim to fad diets, especially fat, which was demonized for years and carbohydrates that are still being wrongly blamed for a host of weight and health problems,” says Stacy Sims, Ph. D., exercise physiologist, nutrition scientist, and human performance researcher. “When you dramatically limit your intake of any one of them, you may lose weight because you’re generally eating a lot less, but ultimately, your performance and health will suffer because they are all critical for exercise and recovery, as well as everyday life.”

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No Magic Macronutrient Formula

When you dig into macronutrients, you find a number of different formulas for what percentage of your daily diet should come from the three macros. Extreme diets will recommend a very high amount of one and very low amounts of another, with some people going as high as 80 percent fat and as low as 5 percent carbohydrates.

Most sports nutritionists, though, recommend avoiding those extremes and shooting for moderate ranges: 45 to 65 percent carbohydrate, 20 to 35 percent protein, and 20 to 35 percent fat. The truth is, though, that there is no one magical formula and trying to track macro percentages in the real world is quite tedious. A better (and easier) approach is to steer your food choices toward getting enough nutrition for what you’re doing, Sims says.

“The goal is to eat enough to keep your energy levels high, to support your workouts and recovery, and to avoid relative energy deficiency in sport (RED-S), a low-energy condition that can disrupt bone health, immunity, protein synthesis, menstrual function in women, and cardiovascular and psychological health,” she says.

Trust us, we know it’s not as simple as it sounds. We’ve all bonked on a long ride, botched our recovery, or had to deal with stubbornly leaden legs, lingering fatigue, and low moods.

So we put together a guide to maximizing your macronutrients according to your activity levels. You don’t need to measure every morsel of food or carry around a calculator. But it’s worth your while to familiarize yourself with the fat, protein, and carbohydrate amounts in the foods you commonly consume and adjust your diet accordingly to be sure you’re getting what you need on and off the bike.


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What it is: Pure fuel. Your body stores carbohydrates as glycogen in your muscles and liver. Each gram of carbohydrate provides four calories of energy. You have about 400 to 500 grams or 2,000 calories worth of carbs stored away to fuel your activity.

What it does: Carbs provide fast energy for your muscles because your cells can convert stored glycogen and glucose (blood sugar that is created when your body breaks down the carbs you eat) very quickly. The higher your exercise intensity, the more carbs you burn. Your body also uses some carbohydrates to assist with fat burning during lower-intensity exercise.

How much you need: You’ll deplete your glycogen stores after two to three hours of continuous low-intensity training or within 30 minutes of very high-intensity training. During long rides, you can maintain your energy levels by taking in 30 to 60 grams (120 to 240 calories) of carbohydrates per hour after the first 90 to 120 minutes. How many carbs you should eat as part of your daily diet depends on how much you train on a given day. Sims offers the following guidelines:

  • For moderate to high-intensity training lasting 60 to 120 minutes, aim for 1.6 to 1.8 grams of carbs per pound of body weight per day.
  • For endurance training involving two to five hours of intense training per day (cycling, running, swimming) aim for 2 to 2.7 grams of carb/lb./day.
  • For extreme training of five hours or more of intense training per day (Ironman or multi-sport events) aim for 2.7 to 3.1 grams of carb/lb./day.
  • For a light or non-training day, aim for 1.2 to 1.4 grams of carb/lb./day. This guideline also applies for short, intense training like CrossFit training, for example.

Where to find it: whole grains, pasta, cereals, fruits, vegetables, beans, potatoes, and other starchy vegetables.


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What it is: Building material. Your body uses small amounts of protein to make glucose during long training bouts that last longer than two hours. Like carbohydrates, every gram of protein provides four calories of energy.

What it does: Protein helps build and repair muscle and other body tissues. It also plays a key role in hormone production and immune function.

How much you need: Endurance athletes need upwards of one gram of protein per pound of body weight, Sims says. She offers the following guidelines:

  • For strength/power phases of training, aim for 1.0 to 1.2 grams of protein per pound of body weight per day.
  • For endurance phases of training, aim for 0.8 to 1.0 grams of protein/lb./day.
  • For a light or non-training day, aim for 0.75 to 0.8 grams of protein/lb./day.
  • For optimal recovery, take in 25 to 30 grams of protein within the first half hour post–event/training session.

Where to find it: lean meat, eggs, fish and seafood, poultry, beans and lentils, nuts and seeds, certain grains (like quinoa, kamut, and amaranth), eggs, and dairy products


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What it is: Fuel and insulation. Each gram of fat delivers nine calories of energy. Even lean people have enough stored fat to provide hours of energy. It’s stored all over your body beneath the skin, as well as in muscle tissue.

What it does: Your muscles burn fat for fuel during aerobic exercise. You need lots of oxygen to make energy with fat, so it’s your body’s preferred source during lower-intensity exercise. Fat also provides insulation, protects your organs, and helps you absorb essential fat-soluble vitamins like A, E, and D.

How much you need: Your daily fat needs don’t fluctuate with your training intensity and volume the way protein and fat do, Sims says. She recommends that endurance athletes aim for about 30 percent of their calories from fat, which you can easily get by eating a balanced, healthy diet.

Where to find it: You still need to be mindful of getting fat from quality food sources, not processed, fried or fast foods. Good fat sources include olive oil, nuts and seeds, fatty fish, and avocados.

How do you know when you’ve hit the right macronutrient medley? You feel good! You have the energy to perform your workouts, and you recover quickly. When your energy intake is off, you’ll find yourself with lingering fatigue and susceptible to getting sick. Instead of obsessing over every number and calculating percentages, tune in to what your body is telling you and aim for a balanced meal at each sitting.

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​Selene Yeager
“The Fit Chick”
Selene Yeager is a top-selling professional health and fitness writer who lives what she writes as a NASM certified personal trainer, USA Cycling certified coach, Pn1 certified nutrition coach, pro licensed off road racer, and All-American Ironman triathlete.