When it comes to building muscle and losing weight, protein is usually the macronutrient that gets the most attention. As a personal trainer and nutritionist, I am constantly encouraging my clients to prioritize protein in their diets, as it helps repair muscle mass and is satiating. However, that doesn’t mean it’s the only macro that matters — carbohydrates are also important.
Carbs have been vilified in many ways, and lots of diets cut them out altogether. However, they have their place in everyone’s meal plan, especially if you are looking to gain weight. Keep reading to discover why cutting carbs may be a huge mistake.
Why do carbs matter for training?
Carbohydrates are the body’s primary and most efficient energy source, especially during exercise. When you train, your muscles rely on glucose, the simplest form of carbs, to fuel movement.
Unlike fats and proteins, carbs can be broken down quickly, making them ideal for supporting both high-intensity and endurance workouts. Without enough carbs, you may experience fatigue, reduced stamina, and slower reaction times.
Carbs also spare protein from being used as fuel, allowing it to focus on repairing and building muscle. One ScienceDirect article states that “Protein sparing refers to the conservation of body nitrogen in a dietary state where amino acids from protein catabolism are not needed as an energy or glucose source, leading to reduced amino acid breakdown and urea synthesis.”
This is important to note for athletes and fitness enthusiasts alike — eating the right amount of carbs can significantly improve performance, consistency, and training outcomes.
The role of glycogen in performance
Glycogen is the stored form of carbohydrates in your muscles and liver, acting as your body’s quick-access energy reserve. During training, especially at moderate to high intensity, glycogen is the main fuel source your muscles draw on to keep you moving.
When glycogen stores run low, fatigue sets in, performance declines, and workouts feel harder than usual. Adequate carb intake before and after exercise ensures these stores are filled, allowing you to train longer and recover faster.
Endurance athletes, in particular, benefit from well-stocked glycogen reserves, but strength trainers and sprinters also rely on glycogen for explosive power and sustained performance.
How do carbs impact recovery and muscle growth?
Carbohydrates play a critical role in recovery by replenishing glycogen stores depleted during training. Refueling quickly after exercise helps prevent prolonged fatigue and prepares your body for the next session.
A meal with carbs and protein makes for the ultimate combo, as it enhances muscle repair and growth. Carbs trigger an insulin response that helps shuttle amino acids into muscle cells. This pairing speeds up recovery and supports muscle protein synthesis.
Without enough carbs, your body may break down muscle tissue for energy, slowing progress. Eating carbs after training not only restores energy but also promotes better muscle adaptations, making them essential for both strength and endurance athletes.
Best carb choices for fitness gains
Not all carbs are created equal, and while you may be tempted to reach for those donuts, choosing the right sources can make a difference in training results. Complex carbs like oats, brown rice, quinoa, sweet potatoes, and whole-grain bread provide steady energy and essential nutrients. These are excellent for fueling workouts and maintaining energy throughout the day.
Simple carbs, such as fruit, honey, or white rice, are best consumed around workouts when quick digestion and fast glycogen replenishment are needed. Timing matters: eat complex carbs before exercise for sustained energy and simpler carbs post-workout for recovery.
