As the inevitable New Year’s resolutions begin, people will consider starting an exercise program to try to lose weight. What could be better than running? It’s a simple, accessible, cheap and very effective way of increasing your metabolism to burn calories. Dialling in the right running intensity will produce the best weight-loss results.
Calories in/calories out — the fuel you consume and the energy you burn — is one concept for achieving weight-loss goals. Energy is stored as carbohydrates and fats and the greater the duration and intensity of running, the greater the amount of energy burned.
The concept relies on burning more calories during exercise and daily activities (calories out) than you eat (calories in). This concept is a good, albeit basic, starting point to weight loss. To achieve your weight-loss goals effectively, the most important factor is the intensity at which you’re running.
Fats are burned most effectively at low intensity, whereas carbohydrates are burned at a greater rate at higher intensities. You can see this in Table 1, which shows data from a metabolic assessment. The final two columns show substrate utilization (fats/carbs burned) during each stage.
In the initial stages (lowest intensity) we burn more fat than carbohydrates. As the speed of running increases, the amount of carbs burned also increases and the fat being utilized drops to zero. This is partly why low-intensity running – long slow distance (LSD) – is so important. Low intensity running burns calories from your stored fat.
Knowing the right intensity for each person is imperative for weight loss, as we all burn different amounts of fat at different intensities. Plus, you don’t want to go so slowly that there is neither improvement in your running fitness, nor increase in your metabolism.
High intensity interval training (H.I.I.T.) or fartlek, might burn more calories, but those calories come from carbohydrates, not stored fat (Table 1). They will be quickly replenished in your diet without any significant effect on weight loss.
After strenuous exercise, your body will continue to burn energy to repair and rebuild. With high intensity running, metabolism remains elevated for some time after exercise.
During this recovery time, the body is at low intensity, using stored fat to fuel this repair process. However, the amount of energy consumed at this low intensity is considerably less than that burned while running at your ‘fat max speed.’
So, when it comes to weight loss, greater gains can be found burning fat running at the right intensity, rather than post-exercise.
High-intensity running still has a role for weight loss and performance improvements.
It is very important to incorporate higher-intensity workouts into your training to increase your metabolism and to run faster.
It is vital to build a program that incorporates both high and low intensity running in the correct ratios and identifying the optimal intensity for you. In training and weight loss goals, most people don’t do their slow running slow enough, or their fast running fast enough.
Gradual progression is key for the effectiveness and longevity of any exercise program. Training volume (distance/duration/intensity/sessions) should increase by approximately 10 per cent each week. Many people fail because they try to do too much too soon.
If you are new to running or you haven’t exercised recently, start with one or two sessions of 20-30 minutes a week. As your body adapts, increase the volume gradually. For example, add 5-10 minutes to each session or add in a third, then fourth session. Slow and steady wins the weight-loss race.
Weight Loss Tips
- Calories in/calories out is not always the most effective way to achieve weight loss goals.
- Low intensity running burns a greater amount of fat than high intensity running, which burns more carbohydrates.
- Incorporate low and high intensity running in your program for maximum gains.
- Avoid injury or failure by progressing gradually.