Archive for month: July, 2025

Nutrition is integral to both health and performance. In order to get the most out of your performance, it is more important to ensure you fuel appropriately, which means fuelling properly before, potentially during (depending on how long your session is), and then immediately after for your recovery. Sufficient nutrition, particularly in daily energy intake, is necessary for the hormonal balance needed not just for progression in your performance, but also to ensure that you prevent metabolic injury (insulin sensitivity, ability to oxidise fats, slower metabolism etc), which in the long run can lead to the body down regulating and preserving energy, which in turn impacts numerous processes in the body including body composition. Ie in trying to lose weight you can end up gaining weight.

First question, is why do you want to do IF? The most common answers are:

• To lose weight
• To lost body fat
• To perform better

What is Fasted Training?

Fasted training is when an athlete performs a session in a fasted state, ie nothing to eat, and trains first thing in the morning. Studies have shown that while there may be some potential benefits to this, the sessions must be recovery or easy sessions, for no more than 60mins and no more than twice a week if you are looking at performance gains. Please note that the benefits (ie initial weight loss and improved fat burning) are usually more prevalent in untrained athletes or people new to training. A trained athlete who is already lean may not see much difference other than negative effects.

When you apply fasted training in longer sessions it has the tendency to add stress to the system and elevate stress hormones. While the body can cope with small amounts of stress, when these stress hormones stay chronically high they may have a negative impact on both health and performance.

In women, the response is more sensitive and can have sever negative consequences to your reproductive hormones (regardless of whether you are past child bearing age – we need our hormones to function well for good health and longevity!) Low reproductive hormones affect your health, lowers mood, impacts body composition and decreases bone health – but more importantly your performance (which is the point of this article). It reduces your capacity to train, your adaptation to training stimulus is reduced, and you are more susceptible to injury.

So why do it at all?

IF is aimed at getting you to reduce calories and assist your body to burn fat at rest more efficiently as well as oxidate fat during long periods of exercise with less reliance on carbohydrate (CHO) intake.

The fact is that most endurance athletes are already pretty good at burning fat as energy just by the nature of their training, especially in endurance athletes with a long training age. So, in general – most of you JUST NEED TO TRAIN to be able to metabolise fats better and lose weight and gain lean muscle.

IF may be of benefit if you are an elite athlete that has reached the point of diminishing returns – ie improvements from training have been limited – then a change in body composition may be of help.

However, for most 40-60 year olds that participate in endurance sports as well as balancing work and families, they have a huge capacity for improvement through training by improving their aerobic development and fitness. So looking at IF here, trying to optimise fat ultisation will not make a substantial difference in performance. Improving your FITNESS will. By improving fitness and your capacity to tolerate a higher volume of work at a higher intensity, this will in turn aid in weight loss and a better body composition. Which let’s face it – is what most of the active population is after. But by restricting calories you are limiting your ability to train at a higher output, therefore compromising these gains.

Train Low

If you feel like you do really need to lose some weight to assist in training better or performing better, you can try a method called ‘Train Low’. The concept is you perform selected workouts with low CHO availability which has been shown to improve endurance performance. It involves the athletes to either do two workouts in a day, using the first to deplete CHO stores (glycogen) and the 2^nd is done in a fasted or low CHO state in the evening. The first session is high intensity and the evening is a recovery or easier session. Or you can do your session at night and restrict CHO intake afterwards so as to remain glycogen depleted overnight. Note that his can effect a session the following morning if high intensity.

Train Low lowers workout quality so needs to be balanced with high intensity workouts with high CHO availability. This concept is bets used when in a maintenance phase or training for general fitness rather than in an event focused phase. I’d advise getting guidance on this through your coach or a trained sports dietician.

Considerations for Endurance Athletes

• Individual Needs:

Not all athletes respond to IF in the same way. Factors like training volume, intensity, individual metabolism, training age, fitness level and overall dietary intake play a role in its effectiveness. 

• Proper Fuelling:

Endurance athletes need to ensure they are still consuming adequate calories and nutrients, especially during the feeding window, to support their training and recovery. The quality of your food choices is also paramount to weight loss, body composition, recovery and performance. Also ensuring that their intake post intense or long sessions enables adequate recovery. Nutrition timing is important if considering IF and athletes may consider only doing IF on certain days to coincide with their training.

• Training Adaptation:

IF may require adjustments to training schedules and intensity to minimise negative impacts on performance. 

• Professional Guidance:

It’s advisable for endurance athletes considering IF to consult with their coach and/or a sports nutritionist or registered dietitian to assess their individual needs and develop a safe and effective plan.

Simone Hayes – Energy Fitness Running – July 2025

Level 3 Trail & Ultra Performance & Development Coach

Level 3 Personal Trainer