Busting Myths about Burning Fat
Body fat is a necessary asset of our bodies. Aside from its well-known function of storing energy, body fat acts as an insulator by preventing excess heat loss, provides a protective cushion around our organs, supports the growth of healthy cells, and regulates hormone levels. For all of the bad rap it gets, body fat definitely plays a vital role in our health!
Of course, too much body fatness has health consequences as well, and most Americans are concerned with having too much rather than too little. In an effort to lose weight, many are looking for the nutrition and exercise regimen that will “burn fat”.
To “burn fat” means that the excess energy being stored in fat cells is being used up as fuel for the body. There are many diets that claim to burn fat more quickly or more efficiently than others, but none of them have proven to hold-up to their claims.
However, exercise is one potential strategy for burning fat.
Burning Fat While Exercising
A few fat-burning strategies exist for exercise. One of them is to train at a lower heart rate zone. Heart rate zones are a range of percentages of your maximum heart rate, and there are health benefits to exercising in each of these zones. The following are five different zones based on your maximum heart rate (MHR)*:
Zone 1: 50 - 60% MHR
Zone 2: 60 - 70% MHR
Zone 3: 70 - 80% MHR
Zone 4: 80 - 90% MHR
Zone 5: 90 - 100% MHR
* You can estimate your maximum heart rate by subtracting your age from 220.
As mentioned, there are various health benefits to training in each heart rate zone. For example, Zone 1 is great for muscle recovery, warm-ups, and cool-downs, while zone 4 strengthens respiratory fitness, enhances carbohydrate utilization during exercise, and improves tolerance of lactic acid build-up.
Zone 2 is touted for improving fat oxidation, which is the technical term for “burning fat”.
So, one potential strategy for burning body fat is to spend some time exercising at 60 - 70% of your maximal heart rate.
Another exercise strategy for burning fat is to train in a “glycogen depleted” state. Glycogen is the storage form of carbohydrate in your muscles. It is the optimal source of fuel for athletes, as it is a quicker source of energy during exercise. Most athletes are interested in honing-in on carbohydrate fueling for adequate glycogen stores. However, some research has shown that training with low glycogen muscle stores forces the body to improve its utilization of fat for exercise fuel.
So, another potential strategy for burning body fat is to exercise in a glycogen depleted state, typically achieved by some form of fasting.
The Myth
But here’s the truth: burning fat does NOT equal weight loss. This is an assumption that many people make when they think about burning fat. Yes, body fat can be used-up as fuel during exercise; however, this does not automatically result in weight loss.
Interestingly, studies have shown that athletes who train in a fasted state do show bodily adaptations that allow them to tap into their fat stores as fuel during their exercise. However, when compared to matched athletes who exercise with glycogen-full muscles, there is no difference in weight loss outcomes. Additionally, there does not appear to be much of a performance benefit either.
The Truth
Weight management is more complex than meets the eye, and using body fat for fuel does not necessarily result in weight loss. And despite our diet culture’s current fears over carbohydrates, adequately fueling your body with carbs from fruits, vegetables, and grains can actually support sustainable weight loss.
Working with a dietitian is a great way to achieve sustainable weight management outcomes and improve your athletic performance. If you would like to work with me, schedule a FREE Discovery Call here!