Updated: Mar 20
The prevailing wisdom regarding weight loss is to eat less and exercise more. On the surface this idea makes sense. How much you eat and how much you move can certainly influence your weight. However, this is a gross oversimplification of the weight loss process, and it doesn’t tell the whole story.
If you believe that losing weight is only about how many calories you ingest and how many you expend, then you may assume that the only role of exercise is to burn calories. You therefore might conclude that
1. The more you exercise the more weight you’ll lose.
2. Since aerobic exercise burns more calories than strength training during an exercise session, you should focus primarily on aerobic exercise.
So let’s create a hypothetical situation. You want to lose weight. But you don’t really want to make any significant changes beyond perhaps skipping desert and switching to skinny lattes, and you’d rather rely on the excess calorie burn that exercise provides.
The Cardio “Fat-Burning” Approach to Weight Loss
So you go to the gym, get on the treadmill, and walk for an hour or more. You come back the next day and do it again. You do this 5 or 6 times a week, and you do this week after week. You would, of course, expect to lose weight.
But there’s a really good chance that you won’t. Why?
Your appetite increases!
The more you exercise, the hungrier you get. I’m talking about actual, physical hunger, not food cravings. The more active you are, the more fuel your body needs.
This is one of the reasons why it is almost impossible to lose weight through exercise alone.
Still relying on the calories in/calories out theory and not wanting to make any substantial changes to your diet, you decide instead to increase the intensity of your workout so you can burn more calories. You get back on the treadmill, increase your speed and ramp up the incline. And you maintain your 60-minute, six-day-a-week fitness schedule.
However, the problem with this strategy is that you may find yourself over-exercising. And this can cause another set of problems.
Why? Because over-exercising causes stress.
Exercising is a type of stress. When you exercise at the appropriate duration and intensity, the body will experience positive stress. Something physiologists call “eustress.” This type of stress causes favorable adaptations in the body that lead to healthier, stronger body.
However, if you exercise too long, too hard and too often this will produce negative stress. Your body will begin secreting elevated levels of stress hormones, including cortisol.
Cortisol, when it is controlled and released in appropriate amounts (which will happen when you exercise at the appropriate duration and intensity) can help you burn fat.
But when cortisol is released in excessive amounts, it can bring your weight loss efforts to a screeching halt. Excessive cortisol will trigger muscle loss, primarily from your upper body, and fat storage around the middle. It will also wreak havoc on your nervous system and your immune system. Moreover, high levels of cortisol are also associated with increased hunger and food cravings.
The “Eat Less” Approach to Weight Loss
So perhaps at this point you decide that you do have to make changes in your diet. Since you’re basing your weight loss plan solely on the calories in/calories out theory, you may decide that you have to drastically reduce your caloric intake and deal with hunger.
Now a little bit of hunger is nothing to be afraid of. In fact, it’s a really good idea to allow yourself to get somewhat hungry before you eat, and to eat until you’re comfortably full.
But if you endure prolonged periods of hunger, you then run the risk of under-eating. And what happens when you don’t eat enough, when you don’t give your body the fuel it needs?
a) Your metabolism slows down. Your body will conserve calories by burning less of them. The body not only slows down the burning of fat, but begins breaking down muscle to be used as fuel, slowing down your metabolism even further.
b) You experience fatigue because you’re not eating enough to sustain your activity level. And how long can you keep up that level of activity when you’re tired?
Under-eating is not only unhealthy and unproductive, but unsustainable. Even if you do lose weight, it will be almost impossible to maintain because of the change in your metabolism and muscle mass.
The Solution: HIIT
The antidote to long and grueling workouts is shorter, more intense aerobic sessions. Enter HIIT.
HIIT stands for High Intensity Interval Training. It isn’t a new concept, but it has gained a lot of attention and popularity, precisely because you can shorten your workouts and get better results.
With cardio HIIT workouts, you alternate brief intensity and recovery intervals, increasing the overall intensity of your workout. How does this work?
First of all, let me introduce the Perceived Rate of Exertion Scale, or PRE. The PRE scale is used to subjectively measure the intensity of your exercise, and it runs from 1 – 10. These numbers rate how easy or difficult you find an activity. For example, 0 (nothing at all) would be how you feel when driving a car; 10 (maximum effort) is how you feel when you run as fast as you can.
1. Very Light
5. Somewhat Hard
8. Extremely Hard
Most endurance workouts, such as walking, running, or stair-climbing, are usually performed at a moderate intensity, or an exertion level of 5-7 on a scale of 0-10.
In a HIIT session high-intensity intervals are done at an exertion level of 7 or higher, and are typically sustained for 30 seconds to 3 minutes, although they can be as short as 8-10 seconds or as long as 5 minutes; the higher the intensity, the shorter the speed interval. Recovery intervals performed at an exertion level of around 5 or 6, and are equal to or longer than the speed intervals.
There are many different versions of HIIT. The program an athlete uses will be far more intense than the person who is exercising for general health and weight loss. Here is a 30-minute interval program geared toward the latter.
· Start with a 5-minute warm-up at light to moderate intensity
· Perform 1 minute of high intensity, followed by 3 minutes of moderate intensity
· Repeat this 4 times
· End with a 5-minute cool down at a moderate to light intensity
If you wanted to challenge yourself, you could increase the overall intensity of this workout by gradually decreasing the resting phase to 2 minutes.
Interval training is for experienced exercises. If you’re new to exercise, start off slow and easy, and build intensity gradually. Start by walking or performing some other type of aerobic exercise for 10 to 15 minutes, and when can walk for 30 to 45 minutes, at a pace that makes you breathe harder and elevates your heart rate, you might try introducing interval training.
In Part 2 of this article I talk about the importance of strength training for losing weight.