People who want to lose weight are wondering what the most effective way to shed extra pounds is – and fad diets or workouts that claim to have the “secret” to shedding fat abound.
According to one theory, training at around 60% of its maximum heart rate puts the body in the “fat burning zone” which is best for weight loss.
But does this zone really exist?
The first step is to understand how metabolism works. Even if you sit all day at a desk to meet your energy needs, the body uses “fuel,” which comes from carbohydrates, proteins, lipids (or fats), and phosphates. However, the rate at which energy is used and the amount available varies from person to person. It depends on several factors, such as food intake, age, sex, and how much or how often you exercise.
In general, low-intensity exercise – like walking at a brisk pace or light jogging – does not require as much strain on our muscles as, for example, sprinting. This means that the body needs less energy and, in this case, it obtains mainly from fat.
However, as the intensity increases, the body can no longer metabolize fat fast enough to meet its energy needs. It then uses up the carbohydrates so that it can metabolize them faster. It can be concluded that there is indeed an intensity of exercise where fat is the main source of energy.
When the body is at rest, the number of calories it needs to function is deficient, so it draws its energy from fat. This means that the possible ‘fat-burning zone’ would lie between the resting state and the level of exercise intensity where carbohydrates become the main source of energy (in terms of percentage of demand contribution. energy).
This is referred to as a zone that ranges from a resting heart rate of about 70 beats per minute to a rate of about 160 beats per minute during moderate exercise (such as cycling at a constant speed where having a conversation becomes a challenge), where we shift from using fat to carbohydrate.
The problem with such a large area is that exercising does not always optimize their ability to metabolize fat. As the intensity of the exercise increases, there is a gradual change in the proportion of fats and carbohydrates used to fuel the body.
Fat burning zone
How do we know when our bodies switch from using fat to using other fuels for energy?
One approach taken by researchers is to assess how much fat is used as an energy source during different intensities.
By measuring how much air a person expels during an increasingly difficult stress test, physiologists have been able to calculate the proportion of fat and carbohydrate used to meet energy needs at different intensities. The greatest amount of fat burned is called the “maximum fat oxidation rate” (or MFO), and the intensity at which it occurs is called “FATmax.”
The more intense the exercise, the less fat our body uses for energy.
Since researchers first used this calculation method, studies have shown that when the intensity drops from about 40% to 70% of VO2 max (the maximum amount of oxygen the body can consume in itself) resulting), there is an increase in the rate of carbohydrates and fats used. The fat level begins to decrease beyond this level because the body needs to obtain energy faster.
The “fat-burning zone” is known to be 50-72% of a person’s VO₂ max. However, the ability to burn fat also depends on genetic factors. Studies have shown that this zone is generally lower in overweight or obese people – at around 24 to 46% of their VO₂ max – and higher in endurance athletes.
Another question to ask yourself is: how much fat do we burn while exercising (in grams per minute)? The answer is: surprisingly few. Even in studies of athletes training at FATmax, participants burned an average of just 0.5 grams of fat per minute, which equates to 30 grams per hour.
things in perspective, a pound of fat weighs about 454 grams. So while training in the fat-burning zone helps with fat loss, this could explain why it usually takes a long time to lose weight while exercising.
However, following certain diets (such as intermittent fasting or a high fat ketogenic diet) and doing longer workouts has been shown to increase the amount of fat you burn.
Maybe it’s time to stop looking for the best fat-burning zone and instead consider that there is an individual “sweet spot” that can be used to optimize weight loss through exercise. physical.
