Is there an optimal pulse for weight loss during training?

Statistically, half of Germans are overweight. And if you ask, who is dissatisfied with his figure, the result is probably a similar picture. Losing weight is therefore one of the biggest motivations for sports. But with what intensity should I train to boost my fat burning in the best possible way?

The question is: where is the optimal fat burning pulse in endurance sports? Running or cycling with this constant heart rate would burn most of the fat, according to the theory behind it. However, three things are often mixed together: Losing weight is not synonymous with direct fat burning and you have to distinguish between the relative and absolute fat burning at a load. Or in other words, one has to first think about the training goal before dealing with the burning of fat.

If someone wants to lose weight, then he actually means a fat reduction, but usually speaks of kilos on the scales. The scale is a bad guide, because short-term weight fluctuations are often due to the water balance and have nothing to do with the desired fat reduction.

Fat burning or fat reduction?

In contrast, endurance athletes specifically train their fat metabolism in order to preserve the body's limited carbohydrate stores (glycogen reserves) during longer competitions. So there are different motives to train the fat metabolism.

Basically, fats serve the body as an energy source. One gram of pure fat stores around 9 kilocalories. So fat can deliver twice as much energy as the same amount of carbs. Fats are a very efficient energy store for the body and they also fulfill other important functions in the body.

Although fats are vital components of the body, a high body fat percentage is still not good for us. On the one hand, the associated weight limits our performance and, on the other, overweight can cause complications such as diabetes or cardiovascular complaints.

So it makes sense to reduce the body fat percentage to a normal level. There are different possibilities for this. In addition to a balanced diet as a basis, sport is a suitable way to burn fat and reduce or maintain body weight.

A good lipid metabolism saves glycogen reserves

Most gyms today still recommend moderate endurance training in the so-called fat burning zone. The background is that although all metabolic processes take place simultaneously in the body, at lower intensities the proportion of burnt fats in the total energy supply is slightly higher.

Because fats need more oxygen than carbohydrates to be converted into energy in the muscles. The faster we walk or cycle, the less oxygen is available and, accordingly, the limited carbohydrate reserves of the body take over the energy supply.

If there is an optimal fat burning pulse, it is more likely to be at a low intensity of exercise. Using spiro-ergometry, the energy metabolism can be measured under load. In the evaluation example of a triathlon beginner (see graph), one can understand what happens in the body when the intensity slowly rises on a cycle ergometer.

Relative or absolute

At the initial load of 90 watts, the proportion of fat burning is 51% of the total energy supply. Relatively speaking, this is the burden of maximum fat burning, because at no higher intensity is proportionately more fat burned. However, the total consumption of 494 kilocalories (kcal) per hour at this level of stress is also relatively low.

In absolute terms, most fat calories are consumed at 180 watts, although the share of fat burning in the energy supply here is only 37%. Nevertheless, this pulse range for an endurance athlete is considered to be optimal for a fat metabolism training. The total calorie consumption here is also over 700 kcal, ie 200 kcal higher than the relatively highest fat burning.

The calories gained from fat are only marginally higher at 180 watts at 287 kcal than at 90 watts. For an ambitious endurance athlete but that plays only a minor role. His goal is to improve the basic stamina with long bike rides in this area and to specifically train the fat metabolism. As a result, the body learns to be more economical with its limited glycogen stores. In competition, the trained runner or triathlete can therefore maintain a high average speed for longer.

For the offensive hobby athlete is training with the optimal fat burning pulse, however, less interesting. Although a fitness athlete burns proportionally more fat calories in this area, the bottom line is the energy balance of the entire day. In order to ensure that a moderate amount of calories comes together through moderate endurance training, you have to train for a long time. In the present example, half an hour on the ergometer at around 150 watts brings just 350 kcal, which is about as much energy as half a bar of milk chocolate. The actual calorie consumption is often overestimated. If you want to lose weight, you either have to work much longer in the fat burning zone or increase the calorie consumption by exercising much more intensively. Through high-intensity intervals can be achieved in half an hour similar high consumption, as in an hour of relaxed training with the optimal fat burning pulse.Furthermore, the intensive training, the so-called afterburning effect is enhanced. Studies have shown that the body has an increased energy requirement for up to 24 hours, if it was previously trained with high intensity. These calories are not only positive in the energy balance, but are covered in the resting phase predominantly from fats, unless you constantly carbohydrates.