Nothing. There is no scientific method. Mostly because it's not really needed. You don't need to count anything anywhere. "I need to lose 2 kg" is a bad goal. Feeling good and being able to live a longer and healthier life is a much more adequate goal.
Just lead a normal life (not even a healthy lifestyle). Reconsider your diet in favor of healthier and healthier food, minimize the number of unhealthy habits such as smoking or regular excessive drinking, exercise, but without much fanaticism. And after a month or two, you will notice improvements in well-being that you don't want to lose. And over time, after such a lifestyle becomes the norm for you, you will see that your body takes on a healthy and attractive shape (if you are not burdened with any diseases that can prevent this, of course) - this figure will be the best for you.
When the "ideal" figure is an end in itself, the lost or gained pounds usually then quickly return, and the process of achieving this goal does not bring much joy. Health should be the goal. And maintaining it is a systematic process, and not achieving a momentary goal like "lose weight / pump up for a date" or "lose 3 kilos, because that's what the calculator on the site says perfect-figure-dot-ru".
Actually, it's super easy. Just calculate your parameters on any detailed online weight calculator. There you will be given both the height-weight ratio, and BMI, and recommendations for losing weight / thickening, and a bunch of useful (and not so) information.
The body mass index (BMI) is considered to be a generally accepted indicator of healthy weight and shape. This is an average value that shows how much the body weight of an adult corresponds to his height. The World Health Organization interprets BMI values as follows:
16 or less - Severe underweight.
16-18.5 - Underweight.
18 , 5-24.99 - Normal, healthy body weight.
25-30 - Preobesity.
30 or more - Obesity.
To find out BMI, Divide your weight in kilograms by the square of your height in meters. Pick a value within a healthy range and aim for it. It is important to understand that BMI is incorrect in a number of cases: for short people, for tall people, and for athletes. A person of average height with a normal BMI may suffer from latent obesity.
Therefore, you need to focus on several indicators at once, which is hard to do manually. Picooc smart scales will calculate everything for you. The device detects body composition and its app displays 12 body metrics, including body fat, muscle, water, weight and BMI. Separately, you can see if each indicator is in a healthy range for you personally. Picooc evaluates body condition on a ten-point scale, and also provides textual analysis of changes in the body and recommendations for further action.
With the Picooc scale, you will always know how many kilograms you need to gain or lose.
For a man, getting in shape roughly means that you need to add muscle mass and minimize the amount of fat (for women, in principle, the same thing, but with an emphasis on the muscles of the lower body). But to what extent - it's up to you personally. Judging by the formula weight = height-100, then, for example, with a height of 180 cm, you need to weigh no more than 80 kg. But these 80kg, even with the same height, can differ significantly from person to person.
Therefore, it is best to focus on the% of body fat. For men, no more than 15-20%, for women 20-25%. But since it is difficult to determine it by eye, it is easier to focus on various formulas such as BMI.
But remember the main thing that you should never be guided by body weight. Focus on the reflection in the mirror! You can lose 10kg of them 5kg with muscles and 5kg with fat, or you can gain 5km of muscle and lose 5kg of fat, but there will be no changes on the scales, however, visually the picture will change dramatically, compared to the first option.
I would say that if you can pull up 15-20 times, push up on the uneven bars 20-30 times, and at the same time you can see at least 2-4 abs cubes, then you are in good physical shape and have diseases of the cardiovascular system, as well as type 2 diabetes (and a bunch of others) will bypass you, but subject to constant maintenance of this form with training (at least 1-2 times a week) and proper nutrition.