Howdy,
Many people would like to know the right answer but there is no way to answer it 100% correctly (when it comes to food) because everyone is “different”. I can give you just basic suggestions about what sounds logical to me, and you need to experiment what fits/works best to your body and taste. Be patient – because it could take a time. I will be talking about general population mainly.
Let’s make some small changes at the beginning and then progress step by step. Some small changes can make a big difference very often! For example, if you start to drink pure water only and include more vegetables in your meals you can see some good both physical and mental benefits. After that, by including fruits and avoiding unhealthy snacks (potato chips and similar) benefits are increasing. Let’s start with some advices intended for general population mainly…

Fruits and vegetables (eat multicolor because of various valuable minerals and vitamins)
First and foremost, I would suggest people not to count calories because it’s so stressful and almost useless (you can do it just in the beginning until you gain some habits and your brain realizes what’s the best amount of food; thanks to technology you can just ask your iPhone about how many calories you just ate, or you can use “My Net Diary” app or similar for example – it’s not only great for counting cals but also for tracking macros and so forth, so give it a try… just be sure to calculate your BMR first + calories burned a day based on your activity level, then eat up to 500 calories a day less than that number to gradually/safely burn your fat stores over time). You need to experiment what fits your body most because there is no “one type of food fits all” rule (I am not sure yet, but sometimes I believe that everyone should eat similar food; there is healthy basics everyone should eat and then you need to adjust details). By eating the whole real foods (organic clean eating) and drinking water you make more benefits to whole your body than any mathematics – especially when you have a habit of eating crap.
If you like counting cals, I will tell you one a bit easier trick. You understand that you need to establish your calorie intake first. You can get your first estimate (not necessarily final – you will figure out during the process) by multiplying your body weight (in pounds) x12. This is good if you are already lean/fit (women <22% BF, men <17% BF). But if you are overweight, you would do well to multiply by a lower number (10 is a good starting point) and adjusting cals from there after few weeks.
Important thing you should take after reading this text is that (if you are from general population who want to lose weight/excessive fat) you should be eating 3 meals per day. But it always depends on your schedule. I suggest 5-6 small meals only for athletes because they need more constant energy during the day, all day – every day. If your goal is burning fat cells I suggest 3 good meals a day (more effective option for fat loss). Otherwise, it’s easier to prepare 3 meals if you have busy schedule than 5-6 meals. But be aware that this works the best only when you exercise. Sometimes calories really matter if you like some highly caloric food and in that case I suggest drinking 1 protein shake just BEFORE meal – on that way you will eat less (this fills you up a bit).
Breakfast: First thing you should do before breakfast (but after brushing teeth and cleaning linguae) is 1-2 glasses (start with one) of plain water on empty stomach and then after 15-20 mins you can take breakfast (I suggest drinking water of 6-12 °C because it works best when it comes to overall health; Japanese love to drink hot water and it’s not bad as well). Breakfast is the MOST IMPORTANT MEAL and the only meal where you can combine carbs and proteins (bread with butter, cheese and boiled eggs – or eggs in any shape; bread with coconut spread and peanut butter – or almond butter – or walnut butter). It will give you a bunch of energy. Bread-butter-jam is also a good mix for breakfast. Of course, bread and other groceries should be organic (whole wheat when it comes to bread). You can eat cereals for breakfast also, with banana and apple inside for example…
You can even eat pizza but ONLY for breakfast. So, never skip breakfast! Remember, for breakfast you can literally eat almost whatever you want (but avoid processed food in general) because our body would kill for energy in the morning – let him get it! There is a need for some serious amount of energy for “long/exhaustible” day (of course, I mean on people who went to bed until 12-1am at the latest previous night, and people who don’t eat a ton of food late at the night).
Any processing (frying, roasting, boiling…) kills good nutrients and enzymes inside food which is not good… Of course, roasting and short boiling is a bit better (as well as frying with the right oil) but still… That food is “dead”.
If you are busy, it’s always good to make sandwich by using things mentioned above. Also, protein smoothies are good to make if you are busy (but I always prefer whole foods). But when I think twice, maybe smoothies are better for snacks, if you take it like a main meal you can be hungry very fast after because it’s already shredded fluid which passes very fast through your guts. Like any else, it depends on person. As I suggested before, if your goal is eating less calories per meal try drinking 1 protein shake just BEFORE meal. Proteins have the highest thermic effect of food (the thermic effect of food is the caloric cost of digesting and processing different macronutrients in your diet).
Lunch: You should avoid mixing carbs with proteins. Bad combinations are: meat and bread; meat and potatoes; fish and potatoes – and bread… I mean, maybe it doesn’t bother your guts but…
If you struggle with gases, indigestion, heartburn, and other gut issues, you may want to give food combination a try. Eating certain foods together and keeping certain foods separate will help you digest food better and will also help you absorb nutrients more effectively. Among other things, never eat protein and starches together. Digesting protein and starch requires different enzymes and other chemicals. To digest each most effectively, they need to be eaten separately. Eat fruits separately and on empty stomach if you don’t want to feel an awful stomach pain like me when I mixed it (apples mostly) a few years ago with nuts 🙂 …
Good combinations are: meat with salad (you should eat salad whatever you eat for lunch because it’s neutral), rice with veggies and a bit chicken or better if it’s only with veggies, fish with salad, beans… If you eat potatoes mix it only with salad – not with meat and bread. Always take a bunch of salad (veggies in general). Rice and chicken is not bad mix but don’t mix it very often. Rice with broccoli and veggies in general is perfect mix.
Dinner: Dinner should be reserved for LIGHT proteins: salad with eggs, salad with chicken, fish-salad… If you don’t eat meat, salad with tofu is good option – or with seitan (it’s the “wheat meat” made from wheat gluten – the main protein of wheat). Salad with tempeh is pretty good choice also. Tempeh is traditional soy product originating from Indonesia. Tofu and tempeh have a lot of proteins!
You should never eat classic pizza by night because there is a lot of bad carbs mixed with proteins. Pizza is only for morning if you like it.
Snack: Snack is also good (if you like it between meals) but depends what you eat. Be careful, it should pass at least 3 hours between meal and snack, and 4-5 hours between 2 main meals. It means your stomach should be fully empty before meal. Handful of nuts is always a perfect choice (almonds, walnuts, peanuts, pistachios, various seeds…). I am always more for RAW organic nuts and food in general. Fruits is also a good option (fruit juice is not fruit – more sugar/calories and no fibers). Try not to mix fruits and nuts because many people have stomach ache when mix it – some substances from nuts could interfere some substances from fruits (not compatible when it comes to utilization – antagonism). Raw nuts aren’t so tasty like baked/fried and salted but trust me after a while you gain habit and it starts to be sooooo delicious! I found that soaked (a few hours before) are the best because you can save your teeth 🙂 , and taste is also better. Remember, anything you take for snack is better than some common “drug” – salted potato chips and similar… Taking 1-2 small snacks per day is more than enough.
When it comes to anything sweet (fruits, black chocolate, ice cream, smoothies…) many nutritionists suggest that you need to eat that only between 5-7pm because it’s the best hormonal response for sweet at that time. You shouldn’t eat fruits immediately after meal because you can make the “bomb” inside your stomach (only at empty stomach because digestion is a way faster than some another type of carbs, fats and proteins).
When it comes to timing, everything depends on what is your rhythm. The hormonal response for breakfast is the best when you take it before noon. Then, after waiting around 5 hours at least (because you eat a looot for breakfast), you should take a lunch (or 1 hour before lunch you can take some small snack). Between lunch and dinner rules are the same like between breakfast and lunch. By theory, you should be avoiding taking dinner after 8-9 pm because hormonal response is bad for digestion – the whole organism is naturally preparing for sleeping by decreasing metabolism, increasing secretion of melatonin and some another hormonal responses etc… Some nutritionists say that it doesn’t matter if you eat a lot for dinner because the total caloric intake counts only but I think it matters because of hormonal responses. You shouldn’t fall asleep immediately after dinner also because it will slower down metabolism even more and food could be incomplete utilized (digestion) in the morning… you are probably familiar with like-a-shit feeling when you get up. You should wait around 2 hours before going to bed.
When it comes to drinking, try not to drink anything except water (and coffee sometimes if your goal is burning fat). Avoid sodas (soda, sweetened juices…) because they are full of sugar and this is the number one contributing reason why people are fat (of course, corn syrup is maybe even greater problem). Some teas are not bad option but plain water first and foremost.
Try not to drink water immediately after meal(s) because it will interfere digestion and utilization of food and it will dilute gastric acid which will make digestion slower and incomplete. It means that you should be trying to drink water ONLY on an empty stomach. The rules are same when it comes to drinking water before meal (it takes 15-20 mins for water to pass through the stomach). Also, if you think you are hungry try to drink 2 glasses of water and that will prolong satiety very often (maybe you were only thirsty).
You have probably heard that we should drink around 8 glasses of water a day. It’s ridiculous because water from food counts also (and there is a lot – take a look at the pic/coincidence below). Of course, everything depends on daily activities and weather occasions.
One more advice, try to exercise when you are hungry (around 3-4 hours after you eat) because on that way your organism will be able to burn more calories from fat cells – which is the main goal for most people! Of course, you can drink some pure protein beverage within that time, for example, because it will not spike up insulin too much. You can read more about this HERE.
One of the best nutritionists said: “Being comfortable with hunger is essential for fat loss”, so among other things, that’s why is the best not to eat anything at least 4-5 hours between meals…
If you live in North America, nice stores are: “Whole foods”, “Fry’s”, “Natural grocers”, “Trader Joe’s”, “Sprouts market”.
Many nutritionists agree that everything we should eat is: FRUITS, VEGETABLES, WHOLE GRAINS, NUTS, SEEDS and BEANS. Of course, healthier meat (avoid red meats) and dairy products are not so bad from time to time mainly because the quality and utilization of their proteins are higher comparing with plants (the eternal question remains whether we are carnivores or herbivores… or mixed, more on this below). The basis of our diet should be basic, not acidic. But of course, everything depends on goals (someone who would like to gain some serious muscle mass shouldn’t eat plants only, or can but with a ton of supplements – I don’t recommend most of them; most athletes likewise).

FRUITS, VEGETABLES, WHOLE GRAINS, NUTS, SEEDS and BEANS
I can’t claim yet, but it seems that the teeth configuration and shape tell us we are herbivores (we have only a few teeth similar to carnivores (animals who feed on meat of other animals) which probably means we can eat meat from time to time. Our teeth and jaw are for grinding fruits and not for tearing meat (the jaw in the herbivore moves up and down and left-right – ideal for grinding while chewing food, in the carnivorous only up and down – ideal for tearing, and swallowing meat). Also, the length of our bowels is much more significant compared with any carnivore (cat for example) and our stomach/gastric acid is much milder compared with carnivores (probably because they swallow an entire animal very often but…). Meat needs “strong” gastric acid and because we have the milder one it requires prolonged digestion and it can start rotting in our LONG intestines. We do not have claws for catching prey, we do have gentle hands for picking up (collecting) fruits. If you don’t believe in the Human Evolution and in that we have lost the most of carnivore lines/traits because we have the most developed brain in the animal world and consequently we don’t need them, you probably agree that we are not anatomically and physiologically adapted to eat other animals. But on the other side, as I mentioned above, an utilization of animal proteins is higher/better comparing with plants so think about it… We know how important proteins are!
All of this is still unclear but one thing is certain, whole your body (especially stomach) and mind mostly feels better when you eat plants almost exclusively. It has even been proven that nutrition by herbs improves endurance, but athletes are another huge topic (I don’t agree that they need to eat plants only). Herbivores are more durable but carnivores are faster and more explosive in most cases. The whole muscular system is made up of high quality proteins dominantly… So, moderation wins again 🙂 .
At the end, one important fact about such an important essential nutrients – proteins. It’s always better to eat around 30 grams of proteins during every meal (30 grams per each of 3 meals) than all 90 grams for one whatever meal. Protein UTILIZATION is better on this way. Proteins are very important and it’s not truth that they damage kidneys and liver if we are “healthy” and do not eat them in enormous quantities. “Any unused protein is burned for energy or stored as fat, and this process can stress the kidneys or liver and may pull calcium out of bones.” – Gabe Mirkin
Thanks for reading and all the best,
Luka