I use the simple system of part time fitness fanatic, full time eating machine. I need a lot of fuel and have often stated that I have one meal a day with breaks for training and sleep. My numerous requests for tips on eating in my sleep have gone unanswered, which has been disappointing if I am honest.
I do find the low carb diets strange and no carb version are literally dangerous, in some cases they have been deadly. Some people are less tolerant to a lot of carb rich foods and that is fair enough but avoiding all of them is lunacy.

Everyone is different but there are a few fundamental clues as to what the body needs in our basic anatomy, something ignored by just about every dietician I have encountered.
The mouth. We have small canines, relatively weak bite force, medium sized molars and incisors with very amylase rich saliva. This means we are designed for a diet with some meat, proportionately little, high quality vegetation that requires little chewing and grinding. The amylase level is a sign that we are ready for a diet high in complex carbs, and the key word there is complex, amylase breaks starch down into glucose, the end result for every energy food we burn, it doesn’t act on sugars so if we were supposed to eat a lot of this we wouldn’t produce as much.
Digestive system. Small stomach, long small intestine and efficient large intestine. The stomach is more for killing any potential infections etc. than digesting food, this doesn’t mean it isn’t aiding digestion but animals eating high quality vegetation general end up eating some pests too, so yes we are designed to be able to kill food based parasites by nature, cleansing or food has reduced this ability. Long small intestine makes us remarkably good at absorbing the nutrients from our food, one of the best complex organisms for doing so in fact. Very little of a good diet will pass through, in fact our waste is mostly cellulose and dead cells from our gut lining, the amount of undigested food is minimal. Calorie wise there is far more from the dead cells than food in our waste, something unusual in the animal kingdom.
Storage, the omnivores defence. We are great at converting excess food to fat and storing it, meaning we survive in uncertain times. Proteins get converted to lipoproteins, carbs to fat and fat has a head start. Without this ability we wouldn’t be here, so much as a bit of unsightly fat is frowned upon when we want to be wearing string bikinis (maybe that’s just me) etc. it is there for our survival. There are good reasons for the minimum ideal percentage body fat levels, take note of them and unless you are genetically very slim stay above them.

Agricultural changes. We have been eating food that we have cultivated for a few million years. Jeny is dairy intolerant, something that would have been fatal at one point in history and was a form of artificial selection when humans started keeping cattle. Milk is something adult mammals cannot digest with almost no exceptions, the digestive system changes after weaning to make it more efficient at dealing with food at the expense of no longer being able to process milk. This is a form of efficiency, after all why waste energy maintaining the ability to absorb nutrients you won’t get again. Human beings found this was a way of getting through lean times. Cattle could produce milk from grass, we could drink the milk so getting goodness indirectly from grass. When this trend first started it didn’t go well, most people were lactose intolerant to the extent they threw up after drinking it. We have forced ourselves to consume something nature never intended, he says enjoying some of the excess milk work has asked us to finish off.

So our systems are a mix of adaptations that have gone on for many millions of years and some that are comparatively recent. The number of people with dietary intolerances to things we cultivate is a sign of how recent this is for us and how long we take to adapt. It is also why we are having such major issues with dietary problems now. We are hard wired to desire things that are hard to find in the wild, rare treats that are sweet, fat rich or salty. The starchy foods we are built for are considered bland because our taste buds largely ignore this knowing it should always be there.
Processed foods aren’t new, salt and sugar pillars have been sold for centuries but now they have become a staple for the majority of the population, and that is dangerous.
Food manufacturers aren’t stupid they know what we are wired to enjoy, so they can get away with feeding us cheap low grade food as long as they add a bit of appropriate flavouring to conceal it. Take one chicken leg, inject with salted water to bulk it out, this alone will taste dreadful and fool no-one into thinking its worth eating. Now fry the chicken coat it in a spiced mix with a bit of sugar and more salt, suddenly you have something people will not only eat but keep coming back for. The recipe is horrifically simple, take low grade junk, add stuff we desire but should avoid, instant processed food hit.

As Jeny said enjoy food where you can. But keep in mind what it’s for, if you really enjoy eating marshmallows and don’t want to look and feel like one keep them as an occasional treat.
I work on a simple system, eat what I need, then what I like. So I have a rice steamer beside me with rice, a bit of soy sauce and some eggs whisked up in it. This is far from cordon bleu cuisine, but it is easy to keep shovelling in during the day. In the evening I will have varied meals and at the end of the day I chill out with a small rich treat while I am relaxing and able to fully enjoy it.
Bad food tastes good, that is an inescapable truth. If you try to make your diet totally pure, I will admire the attempt but know how unlikely it is to succeed. Like cake have some, crisps, wine etc. same thing. The key as Jeny says and I have said so often it should be tattooed on my head is balance. Eat 95%+ of good stuff and allow yourself a bit of indulgence, you will enjoy it all the more.

One area I disagree in is cost. You can eat well cheaper than many eat badly. Marks and Spencer will sell you a ready meal costing more by far than you can buy the ingredients to make it better for a small family. Shop around too, I like Costco because the food is good enough for me in volumes I need and prices I like. I have bought stuff there in a 10kg bag, gone to a farm shop with friends a few months later seen one of these bags in their store room and packs of 0.5 kg of the same stuff at a quarter the price. There are instances where the higher price is due to something being processed by hand instead of a machine, this doesn’t make the ingredients better.
There are definitely a number of occasions when you have to pay more to get better quality and my wife and I made a promise to ourselves 13 or 14 years ago that unless we were full on broke we would never cheap out on food quality. Something meaning our son looks at a lot of food with embarrassing disgust when we visit people and they serve up kiddie meals, but it has been worth it.