Doing fasted weight training or fasted cardio does definitely have benefits and it also has it's drawbacks. Some people might benefit more than others when doing fasted training and some might just do more harm to their body. In this article we will show you the good and the not so good of fasted training and rather how to use it in such a way that you benefit out of it as much as possible.
The pros:
POTENTIAL FOR INCREASED FAT BURN
Some research suggests that exercising in a fasted state (having fasted for between 8 and 12 hours) can boost fat oxidization (or burn) during your workout and as a result, enhance weight loss. So, how does this work?
The body stores fat in two places – in adipose tissue and in the muscle fibres as triglycerides. When we exercise, the body metabolizes both triglycerides and carbohydrates, converting them to fuel. Carbohydrate stores are more readily drawn on by the body because they are easily mobilised and yield energy quickly. But, as those supplies run low, the rate at which the body burns (or oxidises fat) increases.
When working out in a fasted state, the body, already working with depleted glycogen stores, turns more quickly to burning stored fat for energy. This is backed up by a study in the British Journal of Nutrition which found an increase of over 20% in the amount of fat burned during training when fasted.
IT MAY IMPROVE BLOOD SUGAR CONTROL.
The most common concern about doing fasted cardio is hypoglycemia, or low blood sugar, but most studies show that it does not cause detrimental decreases in blood sugar, even for those with diabetes.
Some studies have even found positive effects on blood sugar regulation and insulin sensitivity from exercising on an empty stomach. However, if you have diabetes, you should consult your healthcare provider before starting a fasted cardio routine.
BOOSTS TRAINING ADAPTATIONS
There is some evidence that suggests that fasted training helps boost overall long term performance, particularly in endurance athletes by helping the body adapt to burning fat more efficiently. Working out in a fasted state helps train the body to adapt to low blood sugar levels by burning fat and as a result helps prevent us from hitting the wall or “bonking” during training.
Occasional early morning exercise in a fasted state has been shown to increase VO2 Max– the maximum amount of oxygen an athlete is able to utilize during training in athletic training, and as a result our capacity to perform sustained exercise.
The cons:
MAY RESULT IN REDUCED MUSCLE MASS
Exercising in a fasted state increases the production of the stress hormone, Cortisol, which in turn can lead to the body burning amino acids, which are the building blocks of protein, for fuel. The result? A degradation in muscle tissue and reduced overall muscle mass. One study found that 10% more protein was used during fasted cardio workouts, and another that strength training without fuel can lead to a breakdown in muscle mass. Some nutritionists suggest countering this by taking protein in the form of a shake 30 minutes before your workout, to help prevent the body breaking down muscle.
REDUCED ABILITY TO SUSTAIN INTENSITY
Sounds great, doesn’t it? However sadly, there’s a “but.” As this effect can be negated by the fact that training on an empty stomach and depleted glycogen reduces our ability to sustain intensity during that training session. As the body is forced to turn to burning fat for energy, performance slows, we hit exhaustion faster and may even “bonk” out of that workout altogether.
For most of us that means ruling out HIIT and longer sessions in a fasted state – and in turn, we lose the fat burning and performance benefits associated with them. Essentially, while eating before training reduces mid workout fat burn, fasted training can mean a compromised training session with compromised results.
AFTER BURN IS REDUCED
It follows that while you’re burning more fat when training in a fasted state, research shows that fasted cardio does not increase fat burning overall over a 24 hour period. Why? This primarily relates to the after burn effect.
After burn or Excess Post Exercise Oxygen Consumption (EPOC) relates to energy expenditure and calories burned after a workout. Research shows that this effect is reduced when training in a fasted state, with one study suggesting that ingesting carbs before a workout actually increases the after burn effect.
Like most methods in the world of training you will find some things work for you and some don't. The advice that can be taken out of this article is that fasted cardio has its place and time. If you are a more endurance type of athlete or someone that's main focus is burning fat and losing weight then fasted cardio or fasted weight training is not a bad idea. If you are someone that is more focused on weight training and building muscle and you want to build maximum muscle then fasted cardio might not be in first place on your training schedule. First decide on what your fitness goals are and then plan your fasted training according to this. Also do not over use the fasted training and think the more the better. Use it strategically and with a lot of patience and you will find it work when it needs to.
Gym Cat Team
Exploring the nuances of fasted training reveals a spectrum of health impacts. While it may contribute to increased fat burn and potential blood sugar control, its effects on intellectual health remain a subject of consideration. Striking a balance is key, especially for those prioritizing muscle building, as it may lead to reduced muscle mass and compromised workout intensity. Implementing fasted training requires a thoughtful strategy aligned with individual goals, recognizing that it's not a universal solution but can play a role in overall health, both physical and intellectual.