Yes, it is OK to work out while fasting because the key to weight loss and muscle gain is not just calories and exercise, but hormone optimization.
However in an unfed state, your body doesn't have a ready supply of glucose, meaning your performance is often compromised. This problem is worsened in weight training, with studies showing lifting weights while fasted results lower energy levels, hindered performance, and lower maximum weight ranges.
Recent research suggests that intermittent fasting (IF) does not negatively impact sports performance or lean muscle mass more than any other diet. “But still, the goal is to maintain your health and minimize muscle loss with the right blend of diet and exercise,” explains Kate.
Fasting, prolonged or otherwise, does not cause muscle loss. It's the lack of stimulating your muscles that causes muscle loss.
Lifting fasted is fine. What matters is protein and calories consistent daily, and consistent across a week.
Being fed doesn't necessarily correlate with power, and fasted strength training hasn't shown to be detrimental. However, it is not ideal for hypertrophy as muscle protein breakdown accelerates after fasted training. This will slow both muscle building and recovery.
Catabolic state: Exercising on an empty stomach can increase the risk of muscle breakdown, as the body may turn to muscle protein for energy in the absence of glycogen.
After hepatic glycogen stores are depleted, the body uses adipose tissue and protein for energy. The liver has an active role in the metabolism of fats as it is the main oxidizer of triglycerides. In more extreme versions of fasting, where fat sources have been expended, the body breaks down skeletal muscle for energy.
As stated above, very lean bodybuilders have anecdotally suggested that fasted cardio works best for them, but they are a select group who have a very different set of parameters to work with.
No, creatine does not break a fast. Creatine contains no calories and does not invoke an insulin response. Keep in mind though, this is only if you consume creatine on its own, such as creatine monohydrate powder dissolved in water, unsweet coffee, or unsweet tea.
If you're not training hard enough, progressing, or you're overtraining, you can see muscle mass go down, even if you're in the gym everyday. If your calories or protein are too low, you will see a decrease in muscle mass, even if you are getting stronger.
We conclude that during short term fasting in obese men: 1) serum FSH concentrations decrease, 2) the pituitary responsiveness of FSH and LRH is blunted, 3) serum testosterone decreases, and 4) the urinary excretion of both LH and FSH increase.
Limited research into intermittent fasting paired with regular resistance training suggests that while someone who is intermittent fasting may lose more weight than someone on a regular diet, their muscle gains and maintenance will be largely identical.
That plan is called the 30-30-30 rule. It's a simple but catchy idea that encourages you to eat 30 grams of protein within 30 minutes of waking up and then get 30 minutes of low-intensity exercise. The 30-30-30 rule now has millions of followers on TikTok.
If you are training for muscle strength, and trying to lift as much as possible, you probably do not want to run out of glycogen. There is little endurance required for this activity and explosive quick energy is needed so feeding beforehand is ideal.
A beta-analysis from 2017 looking at five studies on fasted versus fed exercise concluded that working out fasted does not result in greater weight loss or changes in lean muscle mass or fat mass.
So, can you build muscle in a calorie deficit? “The short answer is yes,” stresses Dr Adam. “Whichever way you look at it, a calorie deficit will lead to a loss of energy, initially from our glycogen stores and then predominantly from body fat.”
Decreased training intensity - for many training in a fasted state can result in a less productive training session due to the lack of food. To train optimally you will not do this on an empty stomach.
Eat after you exercise
Eating after you work out can help muscles recover and replace their glycogen stores. Think about having a snack if your meal is more than two hours away. Good post-workout food choices include: Yogurt and fruit.
Lactic Acid Buildup Causes Muscle Fatigue and Soreness. Anyone who has pushed themselves through an intense workout will be familiar with “feeling the burn” — that sensation of fatigue and pain that sets in when you subject your muscles to lifting heavy loads repeatedly or sprinting all-out.
The potential benefits of fasted training include: Enhanced fat utilization: This effect, remember, only holds for low-intensity exercise. Better endurance: Multiple studies have shown that fasted cardio leads to an increase, over time, in VO2 max—a measure of endurance capacity.
However, exercising on an empty stomach will also cause you to lose lean muscle mass at the same time, which can hinder long-term weight loss. Exercising without eating first can cause dramatic shifts in your blood sugar, and when it drops quickly you can feel nauseous, light-headed or dizzy.
Research suggests anytime between 2:30 pm - 8:30 pm is the best for training, assuming your sleep-wake cycle is from about midnight to 8 am. For those who don't fit into the regular sleep and wake cycle, 6-7 hours after waking would be ideal.