Core Principles - High v Low Intensity Training for Weight Loss

Tuesday, 19 July 2011 10:25

High v Low Intensity Training for Weight Loss

Written by Gene Alessi

Low Intensity verses High Intensity Training: Which is best for fat loss?

Fat loss is often high on the list of reasons why people start an exercise program. While there is an abundance of information available on exercise and fat loss, like many things these days, it can be confusing to work out which approach is best. Some people swear by low intensity exercise – with long periods spent in the ‘fat burning’ zone – while others believe high intensity is best.

So which is it? And what will work for you?

Fat loss basics
First, let’s look at the basics of fat loss. In order for fat loss to occur the basic rules of calories in verses calories out apply. At the simplest level, weight loss and fat loss is a simple maths equation – consume more calories than you need and you gain weight and fat, consume less than you need and you lose weight and fat. One kilogram of body fat is equivelent to approximately 7000 calories. In weight/fat loss terms, to lose ½ kilogram a week, you need to consume 3500 calories less than you need. This isn’t done by food alone. Reducing your food intake by 250 calories a day and burning 250 calories from exercise a day will give you the 3500 calorie deficit a week you need to create weight/fat loss. Sounds easy when you put it that way, doesn’t it? Let’s look at the role exercise plays in this equation.

"One kilogram of body fat is equivilent to approximatley 7,000 calories"

Low intensity exercise
Low intensity or steady state aerobic exercise refers to exercise performed at 50-60% of your maximum (100%) effort . Many trainers and exercise professionals will advise people wishing to lose body fat to exercise at this level for extended periods of 40-60 minutes. The theory
behind this type of training is that it forces the body to burn fat for energy rather than using carbohydrates (or glycogen) during exercise.

While participating in low intensity exercise is recommended and beneficial to people who are obese, new to exercise, recovering from injury or illness, or pregnant, studies have shown that regular low intensity exercise can have little effect on body fat levels.

High intensity exercise
High intensity aerobic exercise (also known anaerobic exercise) is performed at 85% or more of your maximum effort. Because you work much harder at this level, sessions are often shorter or incorporated into circuits and interval training (interval training refers to a
period of work followed by a period of rest). During high intensity exercise, your body will use carbohydrate as its main source of energy.

There are a number of benefits to high intensity exercise including improved aerobic fitness, muscle strength and fat loss. That’s right, fat loss. And it all comes down to metabolism and how your body
burns fat. Let me explain.

High intensity for fat loss
When you exercise not only are you raising your heart rate but also your metabolism (metabolism is the process the body uses to convert fat, carbohydrate and protein
into energy). During low intensity exercise, when you are in the ‘fat burning’ zone, your heart rate and metabolism are raised only while you exercise, but with high intensity exercise your metabolism
stays raised after you finish exercising, burning more calories and fat overall.

I’ll give you an example. Let’s say you walk for 60 minutes in the ‘fat burning’ zone. Your heart rate and metabolism will be raised for the 60 minutes you are exercising and within 5-10 minutes of stopping, both will have returned to normal and you will have burnt 420 calories.

Compare this to running for 30 minutes (run for 2 minutes, jog for 1 minute). Your heart rate and metabolism are both raised during this time and you will have burnt 270 calories. Within 5-10 minutes of finishing your run, your heart rate will have returned to normal but your metabolism will stay elevated for up to 8 hours. If your metabolism stays high for just one hour after your run, you will burn an extra 480 calories. Your 30 minute run has now burnt 750 calories compared to 480 calories for a one hour walk!

The answer seems simple. Work harder, burn more calories and lose more fat but in reality there are some important considerations. High intensity training is great for experienced and regular exercisers who are injury free. If you are overweight, recovering from an injury or new to exercise, talk to your trainer first.

High intensity exercise can be incorporated into your regular routine by adding some interval or circuit training.
Give it a try and you’ll soon see the benefits of your efforts.

© Copyright Emma Lions 2010