This is nothing revolutionary, but it is enough for many to have long-term success. Actually … I love this term … we should only focus on the terms import and consumption.
When importing, we have to consider two additional points … I hesitate to start with no-go’s, but it is necessary.

For example, alcohol is a no-go. I like to have a drink or two myself, but then that’s it. You decide for yourself what you want, but alcohol is empty energy. It has no benefits for your body, other than it increases your appetite and pushes your metabolism to an unfortunate NAD+/NADH ratio, which builds up fat.
Refined carbohydrates are also a no-go. They increase your appetite and you effectively take in much more energy more quickly than you can burn it. Stay especially clear of sugary foods and drinks.
Fats are a conditional no-go. By ”fats” I mean the unpopular saturated fatty acids, although these are just as necessary as unsaturated ones. Fatty acids, or esterified fats, are generally not a problem, but an absolute condition. (One only has to look at the structure of the cell membrane or certain signal substances) … It’s simply a question of consumption in excess, which can cause those unwanted tires. My tip: simply avoid them wherever you come across them.

Second preliminary note … stick to the macronutrient diet or the “60/20/20 rule”:
Carbohydrates: 50–65%
Fat: 15–30%
Protein: 15–30%

A look at the biochemistry of the three most important metabolic cycles, the citric acid cycle, glycolysis and beta oxidation, says it all.
I don’t want to say that low carb and the like don’t work, but as Central Europeans we have a certain enzymatic genetic make-up that has prevailed according to the Darwinian principle. In some studies, it has been shown that this mainly leads to an above-average reduction in lean body mass.
So have your carbohydrates … but – and no negation here – be picky about which ones!

Protein is a good subject. Just having a lot of it does not help much. Always take them with carbohydrates. Use your body’s own insulin as a natural anabolic steroid. Insufficient protein intake is not the sole reason for bone problems. It is metabolized and deaminated, and the problem lies in the negative impact it has on your body with nitrogen compounds. This is not necessarily a problem for healthy individuals, nevertheless, a thumbs-up for protein!

And you don’t necessarily consume proteins, fats and carbohydrates, but rather steaks, oils and bread … just as your body doesn’t actually use these either … so let’s leave anabolism aside for a moment and only look at energy metabolism, but even there: what you consume won’t necessarily be integrated into your system, it’ll actually be built up, then broken down, and then destroyed again, and then … no, I’ll stop right there. The process is simply too complex to fit in this blog. So back to energy metabolism: The only currency your body uses is … well … Adenosine triphosphate (ATP). Creatine phosphate also plays a certain role, but that would be another topic as it’s too complicated to get into now. ATP is the US dollar in your energy metabolism. And it’s only enough for a few seconds. Not more. And then it has to be procured again from the glycogen and fat stores, and sometimes even muscle protein must be used. Two interesting directions can be derived from this. Firstly: the reduction of, or depending on the goal, the increase in, stores. And secondly: the consumption of ATP. It is an acceptable simplification of the problem to be limited to carbohydrates, fats and proteins; it is practical. Practical, in a sense, as these substances are on most food labels and therefore easy to find. If you can’t find them, then my advice would be to stay clear of such products. I won’t go into water, electrolytes and micronutrients. These topics alone fill entire books.
Now for the real thing: balance. I want to briefly explain why this is so important to me. At least just as important like as the “material equilibrium”.

Firstly I would like to summarize what I have mentioned above with regard to energy and anabolism.

Someone who wants to build muscle mass, even if they stick to the above facts, is unlikely to succeed with a negative energy balance. The other way round, if you want to lose weight, those pounds won’t melt away with just a positive energy balance, no matter how healthy it is – obviously! So here, too, it is a matter of individual balance. That is perhaps the most general statement I can make here. Biometric data plays a somewhat unexpected role, as do age, gender and illnesses.

It is important when, and after which strenuous activity, what and how much to take. Your body is a very sensitive regulatory system that reacts in a circadian manner, and under stress. It’s a lot smarter than you think and can almost never be tricked. That is what my philosophy is based on.