Calorie restriction has become a popular method of weight management and health elevation. Whether it’s a keto lifestyle, intermittent fasting, or intense fasting, calorie restriction poses some unique challenges in regards to exercising.

In this edition of Healthy is Happy, we share important information on the benefits and issues with exercising while restricting calories. Your body chemistry is unique, so please use these guidelines as recommendations, not rules. Make adjustments as necessary. And always lean on the side of caution and safety when exercising with limited carbs and calories in your body.

Potential Benefits of Fasted Exercise

  1. Enhanced Fat UtilizationNote that this effect only holds true for low-intensity exercise.
  2. Better EnduranceMultiple studies have shown that fasted cardio leads to an increase, over time, in VO2 max – a measure of the endurance capacity.
  3. More Growth HormoneBoth fasting and exercise while fasting increase human growth hormone (HGH). The purpose of HGH is to use stored fatty acids and glucose as energy.
  4. KetosisWhen you fast, blood sugar and insulin levels stay low, which sends the ketosis signal to your body. To maximize the fat-burning, ketogenetic potential of fasted exercise, focus on low-intensity exercise

Downsides of Fasted Exercise

  1. Muscle LossIf someone wants to add muscle, a fasted exercise is not recommended. You don’t need carbs to build muscle but you do need to eat leucine-rich protein (whey) in close proximity to strength training. All of our shakes have Whey protein to help you build muscle.
  2. Less EnergyCertain types of exercise like HIIT (High-Intensity Interval Training), heavy weights, etc. require hard effort to get maximum benefits. But when you train fasted, it is impossible to give 100% effort.
  3. Too Much StressFasting is a stressor. Exercise is a stressor. You need to be careful. Your body has a limited capacity, and if you exceed that capacity, you could suffer.

The most reasonable approach lies somewhere in the middle. If you want to do low-intensity exercise before breakfast, go for it. A 20-minute walk, some light yoga, an easy bike ride. There’s a chance you’ll burn more fat than you would otherwise.

But once the exercise intensity starts to ramp up, you should probably eat something first. Training fed, especially when talking about strength training, gives you more energy, prevents muscle breakdown, and reduces your overall stress burden.

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