Training for performance vs. exercising for weight loss. Yes, there's a difference!
An unfortunately large number of people know that exercise alone is not really an effective way to lose weight. The popular understanding of how this is supposed to work -- simply burning more calories than we take in -- skips over the fact that exercise doesn't require that many calories to start with. At least not enough to make a real difference.
Added to this is the way the body uses stored energy. Typically we think of fat as the only kind of stored energy in the body but in reality there are about 1200 to 1600 calories stored as glycogen in the muscles and liver. This is immediate, readily available energy that the body will always use first before it begins the much longer process of converting fat to fuel. 1600 calories is a lot of energy. Most people do not work out long enough to burn that many calories so their workouts are fueled by glycogen without ever touching stored fat.
Sugar is the body's only fuel. Carbohydrate and fat provide the raw materials that are eventually converted to sugar.
Our bodies are fueled by sugar in the form of glucose. We don't actually "burn" fat, we convert it to glycogen and later, glucose. It's glucose that we actually burn. Think of fat as crude oil. It's very high in energy (9 kcal/g), compared to just four kilocalories per gram of carbohydrate, but it's not in a form that can be used until after a lot of chemistry happens.
So let's say your workout burns about 800 calories. During the next few hours the body will be replacing that energy in the muscles and liver so that you have a 'full tank' for the next bout of activity. Ideally, it would do this by converting fat to glycogen but that's usually not what happens because most athletes have a carbohydrate dense snack following training to speed this replacement process along. Carbohydrate is much easier to convert than fat so fat stores are ignored and the carbohydrate gets processed into glycogen. This is good for athletes, they want their glycogen levels to be at full capacity as much as possible so that training can be done properly, but this is bad for anyone trying to lose weight.
Exercising to reduce weight has an entirely different goal than training for performance. We actually want glycogen stores to be low when we start exercising because that way we will be able to use up this fuel faster, thus forcing the body to begin converting fat to energy sooner. We don't really care if we feel fatigued due to low glycogen levels because we're not training for performance.
To lose weight we have to somehow get the body to create glycogen from fat. So the question is how do we do this?
First, forget about the calorie in, calorie out balancing thing. Our goal is not just to burn calories but rather target which specific sources of fuel we convert to energy. Here's how this can be done:
Step 1: Exercise when glycogen stores are low. For most people this means morning workouts. When we wake in the morning our glycogen stores and blood sugar levels are naturally low since we haven't eaten for a number of hours. Once we eat and begin the day the body uses carbohydrate in our food to replace glycogen. If we can hold off eating for an hour or so then the body uses fat to replace glycogen, which is what we want.
Step 2: DON'T EAT before you exercise. It's important that you keep glycogen and blood sugar levels low. Drink plain water, tea, or coffee.
Step 3: Drink plain tea or coffee to release some fatty acids into the blood. This step is optional but it helps. Caffeine causes the release of fatty acids into the bloodstream. It comes from fat stores so it helps to jumpstart fat conversion. Note that the tea or coffee is plain, no sugar, no milk. Nothing. If you're serious then you shouldn't be drinking your carbohydrates. This means we should not be eating or drinking anything sweet including drinks sweetened by artificial sweeteners.
Step 4: Exercise. You probably won't feel full of energy when you start but in a few weeks your body should adjust to having less glycogen available and get used to tapping fat stores for energy. In other words, the process of converting fat to glycogen to glucose will become more efficient.
The actual exercise should last about 40 minutes to an hour. It doesn't have to be hard but it should be continuous. Walking, running, swimming, or cycling are all good activities because the intensity can be easily adjusted. Curiously, the intensity of the exercise really doesn't matter as far as fat conversion is concerned as long as you get your heart rate up and your breathing rate increased.
Step 5: Wait about thirty to sixty minutes after you exercise before eating. You're using this time to take advantage of your increased metabolic rate, which remains high for several hours following exercise. Your body is working hard to replace glycogen stores in the muscles and liver and guess where it's getting this energy from... that's right, fat! In the absence of carbohydrate the body will begin converting fat to glycogen.
Step 6: Reduce the amount of carbohydrates that you eat in a day. Carbohydrate is a form of sugar so eating any kind of carbohydrate triggers an insulin response that tries to store glycogen in the muscles and liver. If carbohydrate is available then this gets stored quickly. Other nutrients such as fats and proteins also get stored quicker than normal because of elevated insulin levels.
By adjusting when and what we eat we can change how the body uses energy and where it gets it. This method will help with weight loss but as with any serious plan it takes time to show results. Establishing a time each day for exercise will help you stay on track with your fitness and making simple changes to the timing and content of meals will shift the fat burning process into high gear.
Bill Price is the Chief Information Officer at USSA Malaysia in Kuala Lumpur.