It makes sense doesn’t it? If I workout on an empty stomach, I’m taking in less energy and I’m doing a workout, I should burn more kilojoules and lose weight faster right?
Unfortunately, this doesn’t take into account the metabolic and hormonal effect of exercise and purpose of the exercise session in the first place. Exercise is training, for a purpose. It deliberately puts a stressful load on the body in order for it to adapt, become stronger, faster etc. This adaptation occurs when you rest, not when you exercise. The purpose of eating before, during and just after exercise (also known as fuelling) is to provide energy to the body and muscle to get the most intensity out of the workout and protein to minimise the damage caused by exercise. The result is better progression and better long term outcomes from your exercise program.
What are the exact hormonal effects of exercise and how does eating affect this?
When you exercise, especially at higher intensities, your body releases adrenaline and cortisol in its normal stress response. Unfortunately, cortisol dampens your immune system and causes you to retain body fat. To reduce the production of cortisol, you need to consume enough energy (in the form of carbohydrate) before and after your session to minimise this response.
In addition, eating good quality protein before and after your workout, will stunt the cortisol response of training and help begin the resynthesis of muscle tissue. Within 15 min of the end of the session, you should aim to consume 15-20 g of protein (1 x 95 g of tuna).
Low glycogen levels (stored glucose in the liver and muscles), impairing both exercise intensity and training adaptation through reduced post-exercise signalling actions. In addition, low glycogen availability during exercise reduces glucose required for the immune and central nervous system, increasing the risk of infection and chronic fatigue. Proper fuelling before and after exercise reduces the depletion of your glycogen stores during exercise and encourages the restoration of your stores after exercises
The vicious cycle of under fuelling combined with under recovery eventually leads to athletic starvation (less long term energy that you need for activity that you are asking your body to do). The end result is a loss of functional muscle mass and retention of non-functional fat mass, the opposite to what you are trying to achieve.
What does good fuelling look like?
• Before exercise:
o You need to take in some carbohydrates 30 minutes prior to training to help establish fuel reserves, most critical for training first thing in the morning. This should be a fast acting carbohydrate, such as a piece of bread
o The optimal fuel source will contain some high quality protein and a high quality fat eg Cottage cheese and banana
• After exercise (within 30 minutes):
o Similar to before exercise, combine protein with carbohydrate to replenish your depleted glycogen stores, promote recovery and minimise cortisol spike.
o If you gain this energy from real food, be sure to also drink plenty of water
• Within 1.5 -2 hours of exercising:
o Eating a post workout meal replaces the depleted energy and promotes the recovery process further
o Eating this meal within 90 minutes or so of your training session should prevent hunger cravings later in the day
o In the 90-120 minutes following your workout, your metabolic rate is still elevated and your absorption of carbohydrate is higher
o To continue to restore your hydration status to a normal level, water will suffice
- Structure of the meal:
1 cup of high-energy carbohydrates such as Oats or rice
1 cup of low-energy carbohydrates such as Broccoli, carrots, apples for long term energy
High-quality protein, such as tuna, chicken or cottage cheese
Good quality fats – 1 teaspoon of flaxseed oil, which is a very high source of Omega 3 fatty acids
What if I’m trying to lose weight?
It is almost impossible to make smart decisions about the quantity, quality and timing of food and energy intake if you are mixing your training intake with your daily life choices.
Fuelling for workouts is this way will allow you to hit intensity and/or duration with the least amount of negative stress on your body (cortisol production) and allow proper recovery after the training session, setting you up for your next session.
Proper fuelling also facilitates self-control and high quality food choices throughout the day by diminishing the cravings that occur as a result of poor fuelling
Proper daily nutrition will promote general health and support your immune system along the way. However, if you are aiming to lose weight, creating a negative energy balance can be achieved by eating good quality food throughout the day and by increasing your activity level a bit (by going for a low activity level walk), to increase your energy expenditure above your intake level. This means that you provide your body with the nutrition it needs, without compromising recovery and progression in your next exercise session.
Dixon, M (2014) Well-Built Triathlete: Training potential into performance.
In addition, click on the link to listen to Matt Dixon’s podcast on The Physical Performance Show:
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