I get a lot of questions about nutrition, so I'm going to put my answers in one place.
Let's start with a disclaimer. I am not a dietitian. My education has largely been in training, and nutrition has always been supplemental to that. That being said, I have accumulated some experience and knowledge on the issue, and I have made a good faith effort to keep up with the research on the topic. And we cannot forget to mention that this article is for informational purposes only, and does not constitute medical or legal advice. Always defer to "experts" for legal reasons.
We should next address context. I am a martial artist, and a teacher of martial arts. None of this information is designed to get you stage ready for a bodybuilding show or photoshoot. Nor is it geared to get you ready for elite performance on the platform. Our primary concern is maintaining a healthy body composition that allows you to train and perform your sport in a way that is not impeded by weight-related problems. Keep in mind that longevity and optimal performance are often at odds, and so you must prioritize your goals and methods.
If you are interested in "higher performance" nutrition, I will naturally defer to organizations like Renaissance Periodization and 3D Muscle Journey which are run by PhD researchers, teachers, coaches, and competitive strength athletes.
I have already covered some basics on strength and conditioning goals HERE. In it, we covered why being too small or too large are not good. We've even discussed the nebulous concept of body type HERE. So now we can get into the meat of it.
Let's start by addressing "diets". Diet, as a word, just means what you consume. That's it. So when special diets come along, what they are saying is that there is a specific way you should be doing it. The current concept based on the available evidence is sometimes called "Flexible Dieting". And all that really means is that you have a plan to eat purposefully for your goals, but also leave room in the margins to allow for special circumstances (with the implication that you get back on diet ASAP). It takes most of the stress away from eating and allows you to trek forward toward your goals. Of course, the more advanced you get, the more specific your goals are, the tighter those margins become, but then you are not advanced if you're not ready or willing to tighten those margins. And, again, we are not addressing this to the advanced athlete. They are assumed to already understand this, or have a coach helping them through this.
Other types of diets attempt to restrict certain types of food, or seek to control the timing of food. There can be some value in these approaches, but they are never shown to be uniquely beneficial when it comes to body composition. This means that they are not special, not that they don't work. The heavier the restriction, the more stress it can add to daily eating, and especially social eating. This stress is often counterproductive to the goal, as stress modifies things like appetite and hormone production. Dr. Mike Israetel has an older video series talking about nutritional priorities, and how some of the key points of these specialty diets may have merit, but they contribute very little to the big picture compared to calories and macros; HERE.
As an anecdote, I personally like a lower carbohydrate diet combined with intermittent fasting. The fasting creates a better compliance mechanism by training you not to listen to hunger (or false-hunger cravings). It trains you to not mindlessly eat during part of the day. But it doesn't actually contribute to weightloss very well unless you just can't fit the calories into a smaller feeding window (makes it harder to overeat). And that certainly makes it much harder to gain weight. But growing up as a grazer, it was a good move for me to retrain my mind. I have much better food discipline now. Going lower carb, and specifically gluten free, has done something similar. I am not, to my knowledge, gluten sensitive. For some it may be the FODMAPS, as true gluten sensitivity seems very rare. But what it has done for me is it has drawn a line in the sand away from very high reward foods. Foods that create a psychological reward are quite dangerous to your nutrition habits as they promote eating more. Very similar to how drinking too much alcohol makes you tend to drink more alcohol. There are reward mechanisms in the body that tell you to consume more. This is the beginnings of addictive behavior, which is unquestionably harmful. However, NOT EVERYBODY is susceptible to these reward mechanisms the same way, or across the board. And if you can remain in control, there is no need for a restriction. On top of that, these restrictions do not have a universal benefit, and many of the reasons for restriction can create a nocebo effect that will literally create symptoms from phantom stresses.
This is a good place for an aside about vegetarians and vegans. Plant based diets are not uniquely beneficial for longevity, health, or performance. And it is not actually more ethical, as it is harmful to the ecosystem in its own way. So the only reason to go plant based is if you don't like animal products (personal preference) or for religious reasons (which I might not agree with, but you have the right to believe in. For instance, plants are living beings too, and give off distress signals when damaged, thus you're still killing to eat.)
OK, so let's sum up what we have so far: We're after general health and performance, flexible dieting is the standard, and restriction based diets may be useful, but are neither unique nor universal in their benefits. AND YOU DO NOT IMPOSE RESTRICTIONS ON EVERYBODY JUST BECAUSE YOU CAN'T ABIDE SOMETHING.
I guess this means we can get into some simple numbers.
I will largely be using numbers from this Barbell Medicine article as a baseline for our discussion.