Is it better to train fasted or eat beforehand? Most of us have wondered.
You may have heard that training on an empty stomach helps weight loss by burning more fat. Is that true? What about fasted strength training: could it interfere with muscle gain?
Our sports nutritionists answer your questions about sporting performance.
Read on.
What happens when you exercise on an empty stomach?
Coordinate your training and nutrition. Food provides fuel, influencing both results and how you feel during a session.
Some people prefer training early without eating, while others struggle to get moving without food after getting up.
Which approach is right?
It depends.
Personal preferences matter, but so does understanding the effects of fasted exercise beyond your usual habits.
First consider the type of training: strength work, endurance and very high-intensity exercise have different demands.
For a demanding early-morning weights session, eating beforehand is generally more relevant than before a gentle run.
In the latter case, fasted training may feel comfortable depending on intensity and duration. An easy jog lasting under an hour may be an option. With lower carbohydrate availability, the body can use more fat as fuel, although that does not by itself guarantee the weight loss you seek.
An appropriate calorie deficit should be assessed with professional support.
Potential benefits of fasted training
Potential advantages include:
- Training with reduced glycogen availability can increase the body’s ability to oxidise fat for energy.
- It may help spare glycogen during competition and support performance in certain low-intensity endurance contexts.
- Low muscle glycogen may impair a session’s performance while also stimulating cellular pathways involved in muscular adaptation. These competing effects need considering.
Potential problems with fasted training
There can also be disadvantages:
- Glycogen sparing may be useful, but at higher intensities, carbohydrate is a primary fuel.
- Low glycogen can increase amino acid release and muscle protein breakdown, potentially contributing to muscle loss.
- Fasted training can increase fat metabolism while also raising levels of stress hormones, including cortisol and epinephrine.
Planning a pre-workout meal
Understanding how eating or fasting affects performance helps you choose an approach suited to your situation.
A professional can assess your individual needs, refine your nutrition plan and help you reach your goals.
Here are some general considerations for a pre-workout meal.
Eating 3–4 hours before exercise
Research has examined meals supplying 140–330 grams of carbohydrate 3–4 hours before exercise to increase muscle glycogen and support performance.
For prolonged exercise over 90 minutes without access to carbohydrate during the session, the approach discussed includes around 200 grams of carbohydrate 3 hours beforehand to support carbohydrate availability. Quantities need adapting to the person and their tolerance.
What about the hour before training?
You may have heard that carbohydrate immediately before exercise can cause a fall in blood glucose, or hypoglycaemia.
Approaches discussed to reduce this response include:
- Eating or drinking carbohydrate in the 5 minutes before exercise or the warm-up.
- Choosing carbohydrate sources with a low glycaemic index.
- Adjusting the carbohydrate amount, including protocols using more than 60 grams.
- Once exercise starts, consuming carbohydrate during activity.
To Sum Up…
Is fasted training a good idea?
It depends on the sport, duration, intensity and goal.
It can increase fat oxidation. In long-duration events, improved fat use may spare muscle glycogen and support performance in suitable circumstances.
For short strength or endurance efforts relying on ATP, phosphocreatine and carbohydrate, the same benefits may not apply.
Unsure how to plan your meals and nutrition for better performance? Our sports nutritionists can create a highly personalised plan tailored to your needs.
