Fasted Workouts: Do They Really Burn More Fat?

Fasted workouts have gained popularity among those looking to maximize fat loss and improve metabolic flexibility. The idea is simple. You exercise on an empty stomach, usually in the morning before eating your first meal. But does working out in a fasted state actually help you burn more fat or is it just another fitness myth?

I personally do fasted workouts every day. The only thing I have before my workout is my pre-workout supplement, Shaklee Energize. I have trained this way for years and have seen great results, but I also understand that fasted workouts are not for everyone.

In this post, I am going to break down the science behind fasted workouts, the pros and cons, and whether they are the best choice for you.

What Are Fasted Workouts?

A fasted workout means exercising when your body has been in a fasted state for several hours. This typically happens when you work out first thing in the morning after an overnight fast. Since your insulin levels are low and glycogen stores may be depleted, your body is more likely to rely on stored fat for energy.

For a workout to be considered fasted, it must take place at least eight to twelve hours after your last meal. Drinking water, black coffee, or tea is fine, but consuming anything with calories will break the fast.

The Science Behind Fasted Workouts and Fat Loss

One of the main reasons people try fasted workouts is the belief that they will burn more fat. Research supports this idea to an extent.

Fasted workouts have been shown to increase fat oxidation, meaning your body burns a higher percentage of fat for fuel compared to fed workouts. This happens because insulin levels are lower, which allows your body to access stored fat more easily.

Exercising in a fasted state can also improve insulin sensitivity, which is beneficial for metabolic health and may help with long-term fat loss.

Fasted workouts can increase levels of norepinephrine, a hormone that helps break down fat. They may also lead to higher growth hormone levels, which support muscle preservation and fat burning.

However, while fasted workouts may increase fat oxidation during the session, they do not necessarily lead to greater fat loss over time. Fat loss ultimately depends on total calorie intake versus expenditure.

Pros of Fasted Workouts

Fasted workouts may increase fat burning during exercise. Research suggests that training in a fasted state can lead to a higher percentage of fat being burned during the workout itself.
They can improve metabolic flexibility. Your body learns to switch between using carbs and fat for fuel more efficiently, which may support long-term metabolic health.
They might enhance insulin sensitivity. Regular fasted training could help your body regulate blood sugar levels more effectively.
They save time. Skipping breakfast before training means you can get your workout done sooner without worrying about digestion.
Some people report feeling more focused and alert when working out in a fasted state, likely due to lower insulin levels and increased adrenaline.

Cons of Fasted Workouts

They may lead to muscle breakdown. If glycogen stores are too low, your body might start breaking down muscle protein for energy, which is not ideal for muscle maintenance or growth.
Performance can suffer. Some people experience lower energy levels during high-intensity or strength-based workouts when training fasted. This is especially true for longer or more intense sessions.
Hunger and fatigue can be an issue. Working out without eating first can leave you feeling sluggish, especially if you are used to eating before exercise.
It is not ideal for muscle building. If your goal is to build muscle, working out in a fasted state may not be optimal. Eating protein before a workout helps stimulate muscle protein synthesis, which is crucial for muscle growth.
Some people experience increased hunger and cravings after a fasted workout, which can lead to overeating later in the day.

Does Fasted Cardio Burn More Fat?

Fasted cardio is one of the most common forms of fasted exercise. Many people believe it is the best way to lose fat, but research is mixed.

Fasted cardio burns a higher percentage of fat during the session, but the total amount of fat burned throughout the day is what really matters. If you eat more calories later, it could cancel out any extra fat burned during the workout.

Fasted cardio may help with fat mobilization, but it does not necessarily lead to greater long-term fat loss compared to fed cardio.

If fasted cardio is easier for you to stick with, it can still be an effective tool for weight loss. However, total calorie balance is the most important factor in losing fat.

Who Should Try Fasted Workouts?

Those who prefer exercising on an empty stomach. If you feel sluggish when eating before a workout, training fasted may be a good option.
People focused on metabolic health. If your goal is to improve insulin sensitivity and metabolic flexibility, fasted training could be beneficial.
Those who enjoy fasted cardio. If you like the feeling of training in a fasted state and it does not impact your performance, it can be a solid strategy.
Intermittent fasting practitioners. If you already follow intermittent fasting, incorporating fasted workouts may align with your routine.

Who Should Avoid Fasted Workouts?

Those looking to build muscle. If muscle growth is a priority, training fasted is not ideal since eating protein before a workout supports muscle protein synthesis.
People who feel weak or lightheaded when fasted. If you experience low energy levels or dizziness, training fasted is not a good choice.
Athletes or high-performance trainers. If you are doing high-intensity workouts or need to perform at your best, fueling your body properly before training is key.
Anyone struggling with overeating later. If fasted workouts cause you to binge later in the day, they may not be the best approach for your fat loss goals.

Final Thoughts: Are Fasted Workouts Right for You?

Fasted workouts can be a useful tool for fat loss and metabolic health, but they are not a magic bullet. While they may increase fat oxidation during exercise, total fat loss still comes down to calories in versus calories out.

If you enjoy training fasted and it works well for your body, go for it. But if you feel sluggish or notice a drop in performance, eating before your workout might be the better option.

At the end of the day, consistency is what matters most. Whether you train fasted or fed, the key to success is finding an approach that fits your lifestyle and helps you reach your goals.