Fasted exercise

by | Mar 19, 2023 | Nutrition

You get up in the morning and exercise. It’s a great start to your day. In addition, the morning is the only time during the day when you are sure that nothing will get in the way. However, if you want to get the most out of your morning exercise, you need to eat before. Or not?
You can read that training fasted on an empty stomach is the best way to lose weight, and at the same time, you can read in a different article that women should never exercise fasted because it throws off their hormones.

So how is it with fasted training?

  • There are people who do not care;
  • Those who have to eat something in the morning;
  • Those who are concerned that training will impair their training, or may even throw off hormones;
  • Die-hard followers of fasted training.
In this article you will find answers to the following questions:
  • Fasted exercise for weight loss.
  • Is fasted exercise different for women?
  • What if you don’t feel like eating in the morning?

As for nutrition before an early morning workout. The answer is very contextual and it depends on whether the person is obese, a healthy person, or an athlete. It also comes down to how physically active you are, and we cannot forget to consider what is practically realistic for you.

Fasted exercise for weight loss

If you’re trying to lose weight, morning fasted training can help you lose weight, but there’s nothing behind it other than a caloric deficit. There is a lot of advice about how fasted training helps with weight loss due to low insulin levels or increased fat utilization. In the end, however, it is just a good old energy deficit.

However, it should be noted that not all people respond to fasted exercise in the same way. For some people, morning exercise on an empty stomach suppresses hunger, which helps them delay the first meal of the day and thus get into a caloric deficit.

For other people, such exercise has the opposite effect. After training, they would eat everything.

In a study during Ramadan, they found that people subconsciously reduced their activity and thus their energy expenditure by ~10kcal/h after morning fasted training. At the same time, they observed an increased appetite.

Various studies have found no changes in body composition between fasted or fed training groups on weight loss.

29-year-old Veronika, with whom I worked, wanted to lose weight. In the morning, she had a kickboxing class, which she loved. But she couldn’t eat anything before training because it made her stomach upset. When we observed how such training affects her appetite, she noticed that after such an intensive morning training, she would be ravenously hungry. Hunger prevented her from sticking to a caloric deficit and losing weight. I suggested that she include water with protein and a blended banana during training. Banana was hard on her stomach, but she found another source of easily digestible carbohydrates. After including such a shake, she stopped feeling unbearable hunger after morning training, which helped her feel better and prevented overeating later during the day.

If you’re tempted to skip your pre-workout meal to burn more fat, think again. Eating before exercise means less fat burned during training, but that is irrelevant. It’s not about how much fat you burn during training, but whether you’re in a caloric deficit at the end of the day.

Eating excess calories after fasted exercise will get you nowhere.

Fasted training in women

Much of the research on fasted training is on men. But we know that the female body is largely influenced by hormones and is also more sensitive to energy fluctuations during the day and during exercise. In the last few years, more attention in research has started to be given to women as well. There are hypotheses and recommendations based on physiological mechanisms that suggest that the female body responds to fasted training differently than the male body.

For example, women use a higher relative percentage of fat during exercise than men. This could suggest that it will lead to higher fat loss. But in a study of 20 young female athletes, they found no changes in body composition between groups training on an empty stomach or after a meal.

Prolonged time without eating (intermittent fasting) in obese women shows positive changes in hormones.

However, female athletes should pay extra attention to their energy intake and not expose themselves to unnecessary extra stress.

However, there is still little research in this area, so it is good to focus on feelings and your own observations. Tina Gorsek Šparovec, an expert on women’s nutrition, commented on the topic in our interview as follows:

“It is necessary to distinguish between obese, healthy women and female athletes. While losing weight in any way is beneficial for obese women, it is more complicated for healthy women with a normal weight. As long as they exercise fasted in the morning and without negative consequences, I don’t see a problem. Female athletes however, they should be careful. If they train in the morning on an empty stomach and replenish their energy immediately after training, fine. However, training on an empty stomach may cause them not to get the adaptations they are striving for from training. A typical problem is also insufficient energy intake and if they have a shortened time to eat.”

In the context of female athletes, some research shows that even if female athletes have sufficient energy intake during the day, insufficient energy availability during training can have negative consequences in the form of:

  • worse sports performances,
  • impaired digestion (also the reason why many women train on an empty stomach),
  • slowed recovery,
  • bone thinning,
  • irregular ovulation,
  • a worse ratio of muscle and fat mass (due to a longer time spent in the catabolic phase).

What if you don’t feel like eating in the morning?

One of the main reasons why many exercise in the morning on an empty stomach is that they are not hungry. Shortly after waking up, the body may not be ready for digestion, and therefore eating a normal breakfast can be problematic even for dedicated athletes.

It doesn’t mean that you have to eat before your morning workout at all costs. If it is a light training, it is not a problem to train with liquids only. However, when it comes to more intense training, or training longer than an hour, it is advisable to give the body energy as well.

There can be several reasons why we cannot digest food in the morning:

  • the body is not used to eating early in the morning,
  • irregular regiment,
  • unidentified digestive disorders (IBS),
  • coffee on an empty stomach,
  • ovulation.

However, if morning training on an empty stomach leads to insufficient energy intake during the day, you feel bad during it, or you have intense training, it is advisable to consult your situation with a sports nutrition expert who will help you find a suitable strategy.

Nutrition before an early morning workout – how to

I recommend fueling before your morning workout if:

  • you train for endurance sports,
  • you train in two phases,
  • you have a physically active job,
  • are you trying to build muscle
  • you feel extremely exhausted after training,
  • you feel weak during training.

Here are some proven strategies for nutrition before an early morning workout:

  • Have a larger dinner or a smaller second dinner, containing mainly carbohydrates and proteins.
  • Choose a small dinner, at an earlier time. This way, the body will have enough time to digest the food and spend the morning better.
  • In the morning, it is advisable to rehydrate the body. Fruit juices or milk are nutritious liquids that provide you with electrolytes, carbohydrates, and fluids. In addition, they are quickly digestible.
  • Have a small snack. For example a toast with jam.


If your goal is to lose weight, training on an empty stomach, fasted, especially low-intensity cardio (cycling, walking) can suppress your appetite and thus help you achieve a caloric deficit. Training at high intensities tends to cause too much stress and lead to overeating later in the day.

If your goal is to improve in sports, pay extra attention to fueling. To improve, you need to give your body enough energy. For the maximum benefit from hard training and multi-phase training, it is necessary to be well-nourished. In the long run, consistency in training is the main factor for improvement. Inadequate nutrition leads to injuries, illnesses, and reduced adaptation to training.

Ready to Become a High Performing Athlete?

Find exactly what foods, how much, and when to eat for health and performance, but also for joy.