I’m reading a very good book written by Tom Venuto, called “The Body Fat Solution: Principles for Burning Fat, Building Lean Muscle, Ending Emotional Eating, and Maintaining the Perfect Weight“. The principle point of the book is finding the right balance between the calories taken into your body and the amount expended. If you take in more calories than you need, your body stores them as fat. If you take in too little calories, your body will slow down fat metabolism and eat away at your muscle mass. However, it’s not that simple as you still need to maintain the right ratio of protein, fat, and carbs.
In his book, Venuto also discusses the bodybuilder philosophy that I’ve always have embraced that morning aerobic exercise is a “tried and true” fat loss technique; even though there is definitely not a unanimous agreement about its effectiveness, especially in the scientific community.
As a triathlete and a runner, I have always lifted weights to build my body, keep it toned and defined, and to keep my abdominals at the surface. I’ve always weight trained with body builders because their understanding of the body’s muscle can be remarkable. I’ve learned the little things are more important than how much weight is actually lifted – little things such as wrist position, hip rotation, etc….how a bodybuilder will make a lesser weight seem heavier and isolate the muscle better because of a subtle change in hand or body position. I’ve also learned about diet and a few tips to reduce body fat or keep it low with before-breakfast exercise.
Most bodybuilders are die-hard advocates of doing aerobic exercise first thing in the morning before eating their first meal. They believe it will cause them to mobilize more stored body fat and increase their metabolic rate all day long. There’s quite a bit of scientific literature supporting the a.m. fasted aerobic exercise theory, but generally, the exercise physiologists and scientists tend not to buy it. They subscribe to the energy balance hypothesis, which states; as long as you burn more calories than you consume in each 24 hour period, then the time of day you burn them doesn’t matter, nor does whether you burn them from fat or carbohydrate.
It’s important to emphasize that when you do your aerobic exercise or the timing of it is not the most important factor in fat loss. When you do your aerobic exercise won’t make or break you. Simply doing it whenever it’s convenient and following a mildly calorie restricted diet is what’s important. However, there’s a very strong case for doing before-breakfast aerobic exercise if you want to gain every advantage possible to get leaner.
The rationale behind a before-breakfast aerobic exercise goes something like this:
1. When you wake up in the morning after an overnight 8-12 hour fast, your body’s stores of glycogen are somewhat depleted. Doing aerobic exercise in this state causes your body to mobilize more fat because of the unavailability of glycogen.
2. Eating causes a release of insulin. Insulin interferes with the mobilization of body fat. Less insulin is present in the morning; therefore, more body fat is burned when aerobic exercise is done in the morning.
3. There is less carbohydrate (glucose) “floating around” in the bloodstream when you wake up after an overnight fast. With less glucose available, you will burn more fat.
4. If you eat immediately before a workout, you have to burn off what you just ate first before tapping into stored body fat (and insulin is elevated after a meal.)
5. When you do aerobic exercise in the morning, your metabolism stays elevated for a period of time after the workout is over. If you do aerobic exercise in the evening, you burn calories during the session so you definitely benefit from it, but you fail to take advantage of the “after burn” effect because your metabolic rate drops dramatically as soon as you go to sleep.
Research supports this theory. A study performed at Kansas State University and published in Medicine and Science in Sports and Exercise showed that a kilogram of fat is burned sooner when exercise is done in the fasted state in the morning than when it’s done later in the day. The researchers measured respiratory gas exchange, caloric expenditure and carbohydrate and fatty acid metabolism, and found that the amount of fat burned during aerobic exercise amounted to 67% of the total energy expenditure in the morning after a 12 hour fast. This is substantially higher than the 50% expenditure achieved when the same exercise was done later in the day or after eating. A similar study from The Journal of Applied Physiology looked at the effects of aerobic exercise on lipid oxidation in fed versus fasted states. The researchers concluded, “our results support the hypothesis that endurance training enhances lipid oxidation in men after a 12 hour overnight fast.” Yet another scientific paper, Optimizing Exercise for Fat Loss,” reports, “The ability of exercise to selectively promote fat oxidation should be optimized if exercise is done during morning fasted metabolism.”
Despite the fact that increased fat burning from morning aerobics seems logical and is backed by research, there are other scientists and exercise physiologists that vehemently deny its effectiveness. I will discuss their counter argument later this week.
Even though there may be difference of opinion which I will be sharing, from my own personal experience it seems that morning aerobic exercise has enough indisputable benefits to motivate me to set my alarms early and get outside and run. But do what is best for you, your schedule, and your family –do something aerobically daily regardless of what time of the day you do it.
In the meanwhile, I’m going to keep waking up at 5:00 am to hit the running path,swimming pool or the gym.
