In one camp they say you should never exercise on an empty stomach because it can lead to muscle wasting and exercise burn out.
But, in the other camp there are those who swear by working out before eating anything.
In the past I’ve generally encouraged eating something small before exercising, however I’ve swayed back and forth on this in more recent days.
So, what does the research say?
Well, according to one group of scientists, if you want to shift the fat fast you should skip your pre-workout snack.
Evidence Supporting Fasted Exercise
Their 2010 study looked at the effect of running or cycling before eating breakfast, and what this did to the body.
The study was admittedly very small (28 participants), but the results are very interesting nonetheless;
- The groups were made up of healthy, active young men.
- They were given an unhealthy diet of 50 percent fat and 30 percent more calories than they had been consuming.
- One group were told not to exercise (control).
- Those in the other group were asked to exercise four times a week in the mornings, running and cycling at a strenuous intensity. Two of the sessions lasted 90 minutes, the others lasted one hour.
- Participants in the exercise group were split, with one side eating a carbohydrate-rich breakfast before exercising, and carbohydrates (sports drink) throughout their workout. The second group worked out without eating, and only drank water during their training, with breakfast being eaten later in the morning (comparable calorie content to the other group).
At the end of six weeks the non-exercising group had gained an average of more than six pounds. And, they too developed insulin resistance.
The group who ate breakfast before they exercised also gained weight, although this was half what the control group had gained. They also became more insulin-resistant.
So, what about the group exercising before eating breakfast?
Interestingly, they gained almost no weight, and showed enhanced insulin sensitivity. They also showed significantly improved muscular adaptations to training.
Our current data… indicate that exercise training in the fasted state is more effective than exercise in the carbohydrate-fed state to stimulate glucose tolerance despite a hypercaloric HFD (high-fat diet).
So, we should all be working out on an empty stomach…
Not so fast!
Unsurprisingly, there is research to contradict the above.
Supporters of fasted exercise emphasize the idea that working out on empty forces your body to burn stored fat as you workout.
But, some critics of this point out that while you may burn more fat during your workout on an empty stomach, your overall workout output will be lower, and those who burn fat during their workouts actually burn less fat over the rest of the day.
Evidence Supporting Fueled Exercise
So, here’s another piece of research to throw a spanner in the works!
The study published in 2011, took a closer look at this question of exercising on an empty stomach. Here’s what they did;
- Workout 1: 8 men did 36 minutes of moderate cardio at 65% heart rate before eating
- Workout 2: 8 men did 36 minutes of moderate cardio at 65% heart rate after eating
The group who ate before their cardio session continued to burn significantly more calories up to 24 hours after their exercise session.
So, the researchers concluded;
When moderate endurance exercise is done to lose body fat, fasting before exercise does not enhance lipid utilization (fat use); rather, physical activity after a light meal is advisable.
I think it’s safe to say neither study is all that convincing, given the small sample size of both.
Whey Protein and BCAAs
In terms of the first study, I’d be interested to see what the results were if the exercise training had been in a protein-fed state, rather than a carb-fed state.
I think it would have been a very different ballgame!
There is very good evidence to suggest the benefits of pre-workout protein, specifically the branched chain amino acids (BCAAs), which help fuel the muscles during training.
Also, one study found that a scoop of whey protein prior to working out increased the calorie burn over the subsequent 24 hours.
Timing PRO (protein supplementation) before HRT (heavy resistance training) may be a simple and effective strategy to increase energy expenditure by elevating REE (resting energy expenditure) the day after HRT. Increasing REE could facilitate reductions in body fat mass and improve body composition if nutritional intake is stable.
Clearly, the jury hasn’t completely decided whether you should or shouldn’t eat before a workout, so apply a good dose of common sense to the matter, and listen to what your body is telling you.
Why Exercising In The Morning Works
Over the years I’ve become an advocate of exercising first thing in the morning.
Firstly, it gets it done.
When you decide to make exercise part of your life, no doubt you have all the very best intentions. But, any number of things can happen throughout the day to prevent you getting that workout squeezed into an already busy day.
However, when you work out in the morning, you’re much more likely to just get it done without too much ado.
For best results, I recommend regular, high intensity workouts. Personally, I prefer to do them fasted, and then have breakfast right away following the workout. But, that’s just my preference.
If like our first study suggests, there really are additional health benefits to exercising before eating breakfast, well, that’s just a bonus.
Morning Exercise Cautions
There are caveats, of course.
I believe the best approach is to tune in to how your body feels.
I wouldn’t go about recommending that everyone workout on an empty stomach.
Some of you will have a hard time exercising without eating something first.
So, if you are likely to notice dizziness, faintness, nausea or lightheadedness when you workout on an empty stomach, particularly first thing in the morning, you should eat something before you start working out.
Working out on an empty stomach, if you aren’t able to sustain adequate energy levels, means your workout will suffer.
So, if exercise on an empty stomach isn’t for you, go for a small handful of nuts, a shake made with a high quality whey protein powder, or the BCAAs instead.
Whatever method of exercise you choose, make sure you couple it with a healthy diet, and incorporate some high intensity exercises to further maximize your fat burning potential.
I also recommend drinking water only, rather than sugary sports drinks, because they will destroy many of the health benefits of your training. Trust me, you don’t need them!
As I said, you need to exercise common sense on this one.
So, if fasted workouts have you hitting personal bests, then keep doing it.
But, if it leaves you feeling like your energy is lagging and you can’t work to your full potential, eat something small beforehand.
What about you, do you have a morning exercise routine?