July 9, 2025, 8:57 am | Read time: 6 minutes
Many people wonder, “What should I do if I want to lose weight?” The most popular answer is usually, “Consume fewer calories and do more endurance sports.” However, fitness expert and personal trainer Jörn Giersberg recommends a different approach.
When it comes to losing weight, there are essentially two key factors: calorie intake and exercise. If you consume fewer calories than your body uses, you start tapping into your body’s fat reserves. This can be significantly enhanced by increasing daily activity and engaging in sports. Typically, endurance sports are recommended to boost fat burning, such as running, swimming, cycling, or the particularly effective incline walking, as FITBOOK reported in an earlier article. However, sports scientist and personal trainer Jörn Giersberg advises his clients to opt for a different type of training if they want to lose weight.
Overview
What Strategy Burns Body Fat Best?
To be clear from the start: There are many paths to weight loss. Everyone is different and has different preferences. Some find it easy to eat less but are reluctant to exercise. Others prefer not to starve and instead engage in a lot of sports. In any case, discipline and perseverance are needed, as healthy weight loss is a lengthy process that can take months or even years. The path to the goal can vary greatly for each person.
We wanted to know from experienced personal trainer and sports scientist Jörn Giersberg what training he recommends to his clients for weight loss. “In general, I would not track calorie consumption and fat burning during running, walking, or cycling,” says the fitness expert. “I know many people do this because they like to know, but it must be said clearly that not as many calories and fat are mobilized during cardio training as one might think,” explains Jörn Giersberg. This can be rather disappointing.
This Training Leads to Sustainable Weight Loss
Therefore, the personal trainer recommends a different approach to his clients: “I focus more on muscle mass, even for women.” He emphasizes building muscles with dumbbells and heavy weights. Only in this way is the metabolism sustainably accelerated, increasing calorie consumption even while sitting or sleeping.
According to Giersberg, during cardio training, such as running, walking, or cycling, energy consumption is mainly boosted during the activity. And this is not as much as most people assume.
It’s different with muscle building. Here, energy is needed during the workout and afterward for the regeneration of damaged muscle fibers and muscle growth. The more muscles you build, the more calories are burned even at rest. “Muscles are like small power plants, and the energy turnover is significantly higher. Above all, it remains consistently higher, even when I’m doing nothing, like sleeping or sitting in front of the TV,” explains the expert.
The more muscles, the higher the so-called basal metabolic rate. These are the calories burned over 24 hours to maintain all vital body functions. An exact calculation is quite complicated because, ideally, not only do age, gender, weight, and height play a role, but also muscle mass.
“Effort-Benefit Ratio Is Higher with Strength Training”
“Focusing on muscles is much more efficient, even in the effort-benefit ratio through strength training,” emphasizes the personal trainer. As with most of Jörn Giersberg’s clients, time is a limiting factor today. Few people have the time and discipline to train four or five times a week. Most want to achieve success with just one or two workouts a week. “In my experience, you have to focus on muscles,” says Giersberg. Also important: Muscles can beautifully shape the body and make it look firm. Those who only lose weight without building muscle often end up with sagging, flabby tissue. Therefore, according to Giersberg, the priority should always be on strength training.
If desired, it can be combined with a cardio workout to further accelerate fat loss. “But you have to coordinate it very cleverly. Strength training for muscles and cardio are two opposing forms of stress that do not go well together,” explains the fitness expert. It would be counterproductive to combine them randomly. Therefore, it is important to do the cardio workout only as a supplement and not too much. The focus should be on muscle training.
What Weight Loss Training Looks Like
Jörn Giersberg recommends only 20 to 40 minutes of cardio training. “Anything beyond that automatically prevents muscle mass formation.” He would adjust the pace according to heart rate. He recommends the following rule: 220 minus age, and then 65 to 85 percent of that. At the age of 40, you would do cardio with a heart rate of about 115 to 150. This particularly stimulates fat burning in the so-called Zone 2, as FITBOOK has already reported.
For this, the expert recommends a wrist heart rate monitor or, even better, in combination with a chest strap to determine the exact heart rate during training. In his experience, beginners who run by feel are usually too fast.
And when is the best time to do cardio training? “If I do strength training twice a week, I wouldn’t do any cardio in the first 14 days to give the muscles the stimulus to build up.” Giersberg then recommends doing cardio once a week, ideally separately on an extra day. Those who want and have the time can also do cardio twice a week alongside twice-weekly strength training.
For those who don’t have time to do endurance training on an extra day, he recommends doing a short cardio session after strength training—but never before strength training.
The following combinations within a week would be possible, for example:
- 2 x strength training + 1 x cardio
- 2 x strength training + 2 x cardio
- 1 x strength training + 1 x strength training with cardio afterward
It is also important to vary the training. In strength training, this means performing different exercises to stimulate as many muscle groups as possible. In cardio, you can change the duration, pace, and type of sport (e.g., running, cycling, walking, stepper, etc.).
And, of course, training should be combined with a balanced and protein-rich diet.
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Don’t Neglect the Fun in Exercise
Finally, the expert has an important piece of advice: “Training should be fun, that’s crucial.” It’s no use choosing the most effective activity if you have to force yourself to do it every time. “Whether it’s cycling, running, swimming, etc., choose something that you enjoy and suits you,” says Jörn Giersberg. The right conditions (e.g., a running track, a cycling route, a gym nearby, etc.) must be in place. Only in this way can the motivation for regular training and thus for weight loss be maintained.