The age old debate – let’s look at both sides of the argument.

If you’re already devoting the time to working out, you’re probably interested in making the most of that time and getting in the most possible benefit in the shortest amount of time.

When you exercise while fasting, it essentially forces your body to shed fat, as your body’s fat burning processes are controlled by your sympathetic nervous system (SNS), and your SNS is activated by exercise and lack of food. The combination of fasting and exercising maximizes the impact of cellular factors and catalysts (cyclic AMP and AMP Kinases), which force the breakdown of fat and glycogen for energy.

Training fasted has also been proven to go beyond helping you to burn fat and lose weight. Studies also prove that other benefits may help you to:

  • Turn back the biological clock in your muscle and brain
  • Boost growth hormone
  • Improve body composition
  • Boost cognitive function
  • Boost testosterone
  • Prevent depression

As exercise and fasting help prevent muscle aging, which has been proven to boost fat-burning compared to working out after eating. Eating a full meal, particularly carbohydrates, before your workout can inhibit your sympathetic nervous system and reduce the fat burning effect of your exercise in some cases. This is because eating lots of carbs activates your parasympathetic nervous system, (which promotes energy storage—the complete opposite of what you’re aiming for).

Training on an empty stomach will effectively force your body to burn fat, while also offering additional benefits. However if training fasted, it is CRUCIAL that you eat an appropriate recovery meal after your workout to prevent brain and muscle damage from occurring.

The reason being:

When you implement intermittent fasting you put your body into a strong catabolic state. Your body is literally eating up and destroying damaged and injured brain and muscle cells. You rapidly accelerate this process when you exercise in this state. It’s this very powerful synergy that will allow you to effectively rejuvenate your muscle and brain. This is the radical new approach that very few know about and even fewer have implemented.

The MAJOR danger though is that you will need to rescue your muscle tissue out of this catabolic state and supply it with the proper nutrients to stimulate repair and rejuvenation. If you fail to supply these nutrients at the proper time you will hurt yourself.

Your post exercise recovery meal is critically important. It’s needed to stop the catabolic process in your muscle and shift the recycling process towards repair and growth. If you fail to feed your muscle at the right time after exercise, you won’t just miss this window of opportunity to restore and build your muscle, you’ll actually let the catabolic process go too far and potentially waste and damage your muscle.

Eating a full meal, particularly carbohydrates, before your workout will inhibit your sympathetic nervous system and reduce the fat burning effect of your exercise. Instead, eating lots of carbs activates your parasympathetic nervous system, (which promotes energy storage—the complete opposite of what you’re aiming for).
As mentioned earlier, training on an empty stomach will effectively force your body to burn fat, while also offering additional benefits.

Which would I Suggest? Whichever suits you best, and works best for you. It is crucial that you always listen to your body when it comes to exercise and food.

The majority of the “fuel” used during most exercise is not actually coming from the food you have just eaten. If you’re working out at a moderate to high intensity you’re using glycogen and fat that is stored in your muscles, liver, and fat cells. Typically, your body has enough of that stored fuel to last for one to two hours of intense work, or three to four hours at moderate intensity.

Therefore, if you are consuming a high-quality diet, eating every three to four hours, your body probably does not need anything to eat before you begin your workout. Still, some people do have a hard time exercising without eating something first.

Typically these people are more sensitive to changes in their blood sugar levels, which can decline during the first 15-25 minutes of their workout. It is this decline in blood sugar that causes dizziness, faintness, nausea or lightheadedness. This is especially true if you exercise first thing in the morning. Of course, a number of individual factors can also play a role in whether it’s appropriate to train fasted such as your age, when you last ate, whether or not you’re pregnant, taking medications, your medical history, level of fitness, and the type of workout you engage in.

Ideally you goal is to shift your body so it is using fat to fuel the bulk of your energy and shift it away from using sugar that most people are using. It may take a few weeks to shift your body into fat-burning mode and your food choices will be crucial. Rather than consuming 50% carbohydrate you can cut that down by 20-25% and replace that with healthy fats, like coconut oil, egg yolks, butter, avocados, and nuts.

Studies suggest that consuming whey protein (20g protein / serving) 30 minutes before resistance training boosts your body’s metabolism for as much as 24 hours after your workout. It appears as though the amino acids found in high-quality whey protein activate certain cellular mechanisms, which in turn promote muscle protein synthesis, boost thyroid, and also protect against declining testosterone levels after exercise. In practical terms, consuming 20 grams of whey protein before exercise and another serving afterward will most likely yield the double benefit of increasing both fat burning and muscle build-up at the same time.

Again, not everyone will need to eat something prior to exercise, but if you do, a high-quality whey protein is one of your best bets. It’ll curb your hunger while still optimizing fat burning. I believe the best approach is to use some common sense and listen to your body, and if you feel weak or nauseous while exercising on an empty stomach, you may want to eat a small meal, such as a high-quality whey protein shake, before your workout.