Here's an article that takes a different view about dieting than most trainers (although it has some support from the likes of Brad Pilon & his "eat stop eat" ideas). Basically the theory here seems to be you are more active when you are hungry, therefore by allowing hunger to build between feeds you'll burn more calories, by being more active. The basic problem with this idea is he appears to have used animals, not humans to actually test his theory. Basically you could very easily recruit humans for this type of study if you wanted & you could see see how it affects them. Also it does seem to be aimed at those who don't train. We usually have set training times, it may possibly be the case that a sedentary person may become more active eating less, but for those who train (& anyone who trains I call an athlete) not eating enough to fuel training will actually make exercise less effective. There are many studies out there that show this, you need to fuel before, then refuel afterwards if you want to get maximum results.
Obviously there is some tailoring needed. I used to say EVERYONE needs 6 meals a day if they are in training. That is until I started to sort out a diet for this tiny girl who needed very little calories & came to realise that having 3 or 4 feeds a day will work as well for some...depending on your goals.
A big strength guy (or very muscular lady) will certainly need 6+ feeds a day, no doubt if you're trying to gain you'll need to ram in the calories. If you're after holding onto size or losing some fat then you can try some variations. I don't think intermittent fasting doesn't work, I don't think 3 meals a day doesn't work. Some people with hectic lifestyles might find that eating only 3 meals or just not being so careful with their diets but fasting for 1 day a week is the best option for them. It may not be the "Best possible way", if they could get pre-prepared food, find the places to eat, had time to sort out a different plan, but it may be "The best they can manage" & if it gets the results they want then it could well be considered the 'best method', even if it's not what is more commonly advocated.
So with that in mind would 3 meals a day work for someone trying to lose fat...well it could, you'd eat less calories, it depends how it effects your training & metabolic rate overall. If you save 300 calories by eating just 3 meals a day, but by doing that your training isn't so intense & you burn 250 calories less, & because of eating less & the less intense training your metabolism slows so you burn 75 calories less...well you'll see that 'saving' 300 calories actually cost you MORE calories in terms of calories burnt, so it's all relative to total calories in to total calories out not just a simple matter of calories consumed in a 24 hour period.
Generally, unless you're really small you'll need to eat more than 3 times a day if you wish to add muscular size, to loss fat again most people who train tend to do better on more frequent, smaller feeds than less frequent, but bigger 'gut busters'.
I know you're going to ask so here's my basic plan (the guide starts with someone who has zero healthy food) :
1/ My first step is to 'tidy up' someone's diet, so it might be as simple as adding in a wholesome breakfast rather than sugary cereal or white toast. It could be porridge, whole grain toast whatever. Just to get them started on the way to healthy eating.
2/ While they start on the one above I have them order a cook book that contains a selection of healthy eating choices. Once they are comfortable with step 1. I get them to pick 1 or 2 evenings a week & try out a recipe, write down every one you like
3/ Once you have found a few meals you like you can begin to add them into. Now I'm assuming if you've started from zero healthy meals that you eat out as fast food places or make bad food choices when you eat out, so now we need to use the net & the local paper to dig up some places that serve decent food, or if you have no option where to eat learning to pick the best options at the place you have to eat at, so going for the bean salad instead of the burger, or the steamed veggies instead of the fries are what we have to start thinking about. Ideally we'll be searching for local whole food cafés or healthier eating places, by avoiding the obvious junk food places there's less temptation to stray back to your old ways of eating.
4/ Now you should have a decent breakfast every day, a selection of meals you can cook at home & places to eat out around your home & near where you work, so now we start to include more of the meals (& continue trying out a new recipe once or twice a week - let's build up a big list of healthy options). With this you'll also be doing exercise, so now we've got you eating right we can see what tweaks (if any ) you need to lower the fat or add to the muscle mass.
5/ Assuming you're after fat loss & all the changes in diet & exercise aren't getting results then we need to tweak your eating a bit. The first basic idea would be to slightly lower your intake of starchy carbs by a little, losing a few grams of starchy carbs & replacing that with more green veggies will shrink your calories a bit as well as increase your intake of micro nutrients.
6/ We wait for 4-6 weeks to see what results we're getting. Assuming no changes we'll then try lowering portion size once again, this time by keeping the ratio of foods the same but cutting equally from every portion on the plate (take a little off everything).
7/ during points 5 & 6 where we are cutting calories it is important for every athlete to know something about refeeds. Planned refeeds are an important part of a dieting plan once you start cutting calories & can even be used in a general healthy eating plan to allow for structured eating of 'junk' food. A refeed does not have to be junk food, having a huge whole grain pasta meal followed by a healthy high calorie dessert can be a refeed meal. Some people advocate refeed days & they 'can' have there place in a diet, but as a rule I like to stick to refeed meals. Looking at it from a realistic perspective, it's harder to over eat in one meal, than in one day. Suppose I have a night out planned, so I pencil in my refeed meal for that evening. I could go out, have a meal, a glass of wine & a dessert, yep that's going to be a bigger than normal calorific intake, but if I get up have fake cream muffins & custard for breakfast, then later that day warm coconut fat poured over a full sized vegan pizza & fake ice cream for afters for a snack, then a few hours later a packet of biscuits dunked in fake cream, then in the afternoon a full roast dinner with all the (vegan) trimmings followed by a stupidly high calorie afters..oh yea & snacks inbetween (as it's a refeed day) of crisps & other high cal stuff. Then I can see you hitting a whopping calorific intake, whereas one meal...even a gut buster is kind of self limiting, you can only eat so much in one sitting however much you'd like to eat more, so there is a built in 'damage limitation' . So, I do say it's worth having 'structured refeeds', by structured refeeds I mean planned, if you don't plan the meal, you just say "I'll do it when I feel like it", you will tend to slip & one weekly refeeed will soon become 2, then 3 etc. Also by planning your refeed you can have what you really want, say you love pizza, well ok, you're planning to go out on Thursday, so you can eat that pizza with your friends, even have a dessert if you like (wow you can get that new vegan ice cream you wanted to try out). You're not mesing up your diet, it's part of the plan! Also if you know you are going to have it on Thursday, when you get that urge on Monday, you can say "OK I won't have that pizza today, but come Thursday YOU ARE MINE!". Why have a refeed at all you might be asking, wouldn't you lose more by not having a refeed? We'll lucky you asked, as it happens when you eat below maintenance several things happen to your body after a few days, the thyroid decreases output, so your metabolism slows, you tend to become more efficient at using calories as well, this double whammy means that you end up feeling like you have less energy while at the same time you use less calories. A refeed sends a message to brain "No worries, plenty of food available let's start burning!", the thyroid boosts production & the body feels it can afford to burn a few extra calories. So you can actually lose fat by adding in a refeed once (or at most twice) a week (I tend to start on 1 a week & rarely need to put people on 2). A refeed meal is one meal, not an evening of binging, plan it, don't just go crazy from 6pm to 2am having a beer & junk fest. As I said earlier it doesn't have to be junk, it can be just a big helping of a high calorie meal, the secret is it MUST be higher calorie feed. Having an extra spoon on legumes on your bean salad isn't a refeed it has to send a message to your body to loosen those controls, boost that thyroid & slacken off on being so efficient with those calories, so you need to eat a decent amount of calories in that meal. Junk is ok, high calorie health food is ok. A couple of things to avoid hydrogenated fats shouldn't be eaten as a refeed, they are poison, don't eat them at all if you can avoid it, heated oils that are high in EFA's shouldn't be eaten as they become carcinogenic so stick to fats that are mainly monounsaturated or even something like a coconut oil which is high calorie but heat stable - it's a refeed so high fat is not your enemy today!
8/ Beyond this if the fat still isn't coming off then we'd have to start tailoring your diet with ideas like no starchy carbs in the evening, carb cycling (assuming you are are carb sensitive type), a fat sensitive type will do better having fat cycling days. I've never heard, nor come across a protein sensitive type (someone who stores fat easily with higher protein intakes) they may exist, but I know no one who has found one. Most people who need to lose fat are either fat-sensitive, carb-sensitive or a combination. That is carbs tend to make the carb-sensitive person fat more easily, while fat makes the fat-sensitive person fat more easily. These both need different approaches to diet & VERY different diets. Most people will not be one extreme or the other, but if you tend to be more one than the other knowing will help you with any changes you need to make if the weight just isn't coming off. Bear in mind that most people will achieve their results without the extremes of carb cycling etc, for most just eating a balanced wholefood diet will be enough to get them into shape once they start training, if you need to go further than that I would suggest you find some help (this can be a nutritionist or even a book if the cost of a health adviser is too much).
9/ Final points. I would try & keep a food dairy starting a week or 2 before you start making changes. Get an idea of what you are eating. Yes it's a pain & yes sometimes if you eat out you have to guess at a calorific intake, but it gives you a baseline. This is what you are eating now. After that I would work out the amounts of the new foods you are introducing, then keep a rough track (detailed is ok too, but most people don't have time to track every calorie in detail everyday), if you get to stage 8 & the fat still isn't coming off then it's time to REALLY use the food diary & start working out totals & working out how to cut those calories. This is where a food expert can come in handy, they can do the hard work for you, they can swap round your foods & suggest things you may not have thought of. I would keep in that structured refeed or loses will not happen so easily, but a tweak here & there can be all it needs to get things moving again. You can do this yourself, it takes time, a pen & paper & a calculator but you can do everything you need with a basic book on dietary needs (in the case of most vegans that be be to include a vitamin B12 source, an omega 3 Essential Fatty Acid source & if you live in a cooler climate a vitamin D during the colder months as minimums all seem to be common things that most vegans need to address).
That's as far as I'd like to go a general dietary plan. If you're starting out right now today, then get a food diary & do a bit of weight & measuring, keep tabs & move slowly towards a wholefood diet & away from refined foods. That along with some exercise will be enough for many of you to get into fine shape & never have to even worry about calories or dieting.