Fasted cardio, often proclaimed as a strategy to enhance fat burning, is a term used for cardiovascular exercise that is done on an empty stomach, typically in the morning before eating breakfast.
But does this practice truly deliver the promised benefits? Before we reach any conclusions, we first need to cover some basics.
HOW YOUR BODY USES ENERGY
Before we can talk about the benefits of fasted cardio, it’s crucial to understand how our bodies use energy during exercise. There are primarily two pathways:
ANAEROBIC PATHWAY
This pathway kicks in during high-intensity exercises like HIIT (High-Intensity Interval Training), weightlifting, or any type of short bursts of intense activity. Glycogen, derived from carbohydrates, and creatine phosphate serve as the primary fuel sources here.
AEROBIC PATHWAY
The other pathway is known as the aerobic pathway, and your body uses this for low-to-moderate-intensity exercise such as power walking, light jogging, or steady-state cardio. The main fuels for this type of exercise are glycogen and fat.
When you start any type of exercise, you will be in the aerobic/fat-burning zone. As your exercise intensity increases, you will switch over to the anaerobic pathway at a certain point. The fitter you are, the longer you can stay in this fat-burning zone.
RELATED BLOG POST: How To Get Lean Legs: Why You Need Cardio For Slim Legs
When you do cardio at a low to moderate intensity, the body’s preferred fuel is glycogen (carbohydrate) first, and then fats. However, the longer you exercise, the more fat your body will burn.
HOW FASTED CARDIO IMPACTS OUR HORMONES?
It’s important to mention that fasted cardio can influence female hormones in various ways.
For some women, exercising on an empty stomach may disrupt hormonal balance, particularly cortisol levels. Cortisol, often referred to as the stress hormone, can rise during fasted exercise, potentially leading to increased stress levels. Elevated cortisol levels may also interfere with other hormones, such as estrogen and progesterone, which play crucial roles in menstrual cycle regulation and overall reproductive health.
However, the impact of fasted cardio on hormones can vary significantly among individuals, with some women experiencing minimal disruptions while others may notice more pronounced effects. It’s essential for women to listen to their bodies and monitor how they respond to fasted cardio, adjusting their workout routines accordingly to maintain hormonal balance, their personal fitness goals, and their overall well-being.
Is HIIT Making My Legs Bigger Or Smaller?
SO IS FASTED CARDIO BENEFICIAL?
So to finally answer the question, it IS beneficial to do fasted cardio (but keep in mind, all in moderation). This is because you have not eaten anything for a fairly long period of time, so there is not much glycogen (carbs) stored in your body, and as a result, you will end up burning more fat. Fasted cardio works better if you haven’t had a lot of carbs to eat for dinner.
It is best to do low-to-moderate-intensity cardio in the morning. If you tried high-intensity exercise, your body would not have as much energy for it. Therefore, you would not be able to do as well during your workout. If you are fit, you would likely still burn more fat doing higher-intensity fasted cardio, but it is generally not recommended.
Long, slow cardio is not the most effective way of losing weight. However, it is beneficial if your goal is to have a lean and more toned physique. You will not gain muscle doing this type of exercise, but you won’t necessarily lose muscle either. Read more about how to use fasted cardio to lean out your legs here.
What’s The Difference Between Resistance, Strength, And Weight Training?
WHEN SHOULD YOU AVOID DOING FASTED CARDIO?
These are some situations when you should avoid doing fasted cardio, in order to prioritize your health and well-being:
- Medical conditions: Women with medical conditions such as diabetes, hypoglycemia, or any other condition that affects blood sugar regulation should steer clear of fasted cardio. Exercising without sufficient fuel can exacerbate these conditions and lead to adverse health effects.
- Hormonal imbalances: Women experiencing hormonal imbalances, such as irregular menstrual cycles, amenorrhea, or polycystic ovary syndrome (PCOS), may want to avoid fasted cardio. Intense exercise in a fasted state can further disrupt hormone levels, potentially increasing existing imbalances.
- Pregnancy and breastfeeding: Women who are pregnant or breastfeeding should avoid fasted cardio to ensure they maintain adequate energy levels for themselves and their baby. It’s essential to prioritize nutrient intake and avoid unnecessary stress on the body during these fundamental periods.
- Recovery from illness or injury: If you’re recovering from illness, injury, or surgery, you should refrain from fasted cardio until you have fully regained your strength and stamina. Exercising in a fasted state can impede the body’s ability to recover and may prolong the healing process.
- Chronic stress: Women experiencing chronic stress, whether due to work, family responsibilities, or other factors, may benefit from avoiding fasted cardio. Elevated stress levels can already impact hormonal balance, and adding fasted exercise to the mix may further enhance stress-related symptoms.
CONCLUSION
Adding fasted cardio to your workout routine should be a personal choice. Whether you choose to exercise on an empty stomach or not, the key is consistency.
Regular physical activity, coupled with a balanced diet, offers numerous health benefits, including the potential for sustainable weight loss. But if you’re new to fasted exercise, it’s best to ease into it gradually. Allow your body time to adjust to any changes in your workout and dietary habits, and find ways to be active that work best for your personal goals and your lifestyle.
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41 Responses
Hi,
I try to eat when I wake up as to not mess with my hormones and cortisol. does fasted running also work if i eat a breakfast with little to no carbs in it?
Thank you
Hey lovely, yes it still does work! Also, studies say that there is no difference in calories burned over 24 hours between people who eat or skip breakfast. So to answer your question, your metabolism won’t slow down if you skip breakfast and do fasted cardio and you will burn more fat if you keep your body in the fat burning zone <3 Hope this helps! xx
Hi, nice article! ive read that exercising without eating breakfast keeps your metabolism slow so you burn less calories. so if i walk in a fasted state does it actually matter that my metabolism is slow and will i burn fat?
Hey lovely,
Thanks for reaching out!
Actually, studies say that there is no difference in calories burned over 24 hours between people who eat or skip breakfast. So to answer your question, your metabolism won’t slow down if you skip breakfast and do fasted cardio and you will burn more fat if you keep your body in the fat burning zone :)
Let me know if you have any other questions!
Love,
Marina