First of all, what does it mean to be in a fasted state? When one’s muscles are depleted of glycogen stores, one is on a fasted state. And this can be achieved by, for example, not eating before exercise or through a low-carb diet. So one will usually lack stamina or strength while doing exercise in a fasted condition. However, fasted training has a different effect on anaerobic and aerobic exercise. And one’s goals are a factor as well. Should a trainee, who is looking to gain as much muscle as possible, train in a fasted state? Is fasting beneficial to someone who is about to run a marathon?
In general, one will usually feel more lethargic while exercising in a fasted state. Muscles, after all, prefer carbohydrates for fuel. And this applies to both cardiovascular exercise and strength training. So a trainee, who is prioritizing the barbell squat in order to gain size on his legs, will feel weaker while lifting weights if he is fasting. And in order to get stronger, in the case of weight lifting, one needs to add weight to the barbell over time. The same can apply to a runner. A runner can feel lethargic while running in a fasted state. And if he needs to improve his mileage, he might not see benefits from being depleted of carbohydrates during training.
Fasted training can be convenient for trainees that are mainly interested in losing weight. Not everyone is mainly interested in performance. And not all trainees are interested in maximizing muscle growth. And the key here is maximization. There are trainees who are just interested in weight loss. And in the case of beginners, they will see improvements in conditioning and strength in almost any type of fitness program. So a runner, who is mainly interested in losing weight, could benefit from training in a fasted state. According to researchers, the body tends to utilize fat for fuel while fasted. Not only that, but fasting can bring benefits in insulin sensitivity as well. Also, a lot of trainees practice Intermittent fasting. This means, for example, that a trainee might only eat during a 10-hour window. So for those who practice intermittent fasting, training in a fasted state can be highly convenient.