Finally coming back to post. I knew I was going to want to say a lot and I also knew this was going to have to be when I had some hours to spare.
First off, the disclaimer. I am not a medical professional. I am also not a fitness trainer. I'm just a smart guy with a lot of info. If you see me flubbing something, then fer gods' sake call me on it before someone gets hurt. Also I will learn more. Now, on to the story...
The previous posters are absolutely correct. Your weight/BMI, while a useful tool, is not the One True Metric that you should use as your basis of success/failure. You hear me? Throw it out. Check it every couple of weeks to make sure you haven't varied a dangerous amount, but otherwise just ignore it completely. Plotting your daily weight on some kind of chart is like peeking under the Band-Aid to see how your wounds are healing. Just like with burns and pavement rash, the way you feel is a much better indication of your progress than how it looks.
And as far as calorie counting goes, everybody is right, for the most part. Calorie counting is important, but it's not the sort of thing you need to obsess over and document and chart unless you need to lose weight for medical reasons. See, your body needs energy to do stuff, and it gets that energy by burning fuel that you have eaten. This fuel comes from one of three places: From carbs/sugars (stuff you just ate), from fats (stuff you ate a while ago), and from proteins (stuff you thought you were done with). Let me give you a couple of analogies as to how this works:
[Analogy 1: FIRE]
You want to maintain sufficient fire for your needs. At the same time, you want to make sure you are not amassing a huge pile of leftover wood to clutter up the place. Keep in mind that you can manage this fire through the addition of different types of fuel, so if you know you're going to need more fire, you can send down more fuel against your expected future needs. But here's the catch...you don't actually load the firebox. The only thing you can control is how much fuel you send down, and what kind, and if you send down more than you actually need, the excess gets pressed into bricks for later use and left lying around.
Now, if all you send down is branches, newspaper, kerosene, and pine needles, your system is going to get a little crazy. See, the guy feeding the firebox is always going to prefer to toss in the easy stuff first because it's the most convenient, but because the level of fire is going to vary so much because this stuff burns so quickly, you're going to get refueling demands which also vary wildly in their urgency, ie your appetite will be all over the place. If your diet is more fat-heavy, then it's more like you're sending down nothing but logs, which is great for overnight or long-term steady state but which is lousy if you really need a quick burst of energy. And if you ever get to the point where you're burning your own protein for energy? Well, that's a bit like breaking up the furniture for fuel...it's not a long-term solution, and you want to avoid it if possible.
You can see why eating multiple small meals throughout the day makes more sense. If you keep the flow steady, you have a much better chance of staying on top of demand. Snack wisely for JIT delivery of energy and your body will be less likely to panic and try to throttle you back so it can lay in a full Winter's supply of fuel "just in case."
[Analogy 2: FINANCE]
(For this analogy, imagine that your ultimate goal is to stimulate the economy as much as possible instead of saving for your own retirement. Just go with me, here...)
You are trying to make ends meet. You have earnings and you have bills to pay. When possible, you try to pay them all out of your paycheck/cash (carbs/sugars), because doing so is much more fluid. When you can't, you reach into your savings/retirement (fat reserves) when it's going to be a while until your next paycheck. When things get really dire, however, then you have to mortgage your own stuff (burn protein) in order to keep up with demand. This is a bit counterproductive, since you will eventually want to put that stuff back.
Again, you can see why eating several small meals is a benefit. It's more like getting paid every week instead of bi-weekly or even monthly.
Furthermore, there are finer points to consider. Carbs come in quite a variety. Sugars are generally metabolized very quickly, which means they are good for ENERGY NOW DAMMIT situations, but they don't last for very long. Additionally, too much sugar can spike your insulin, which will lead to that "crash," or even possibly diabetes if it happens too often. Your body prefers to get its sugars in about equal amounts, which is why sucrose (table sugar) is so good. Internally, sucrose breaks down into glucose and fructose, and both go on their merry way through your system. The problem with sodas full of HFCS is that it is mostly fructose, which upsets that balance. Glucose can be used pretty much wherever it is needed, but fructose has to be metabolized in the liver, so if your diet is disproportionately composed of fructose, then you are making your liver do a lot more work than it needs to, as well as forcing your cells to wait around for your liver to get done processing their energy supply.
More complex carbs (starches, minimally refined pasta, whole grains, oats) take longer for your body to metabolize, which is why having oatmeal with maple syrup or fruit for breakfast works so well. Your body seizes the sugars and puts them to work immediately, but because it has to work a little harder to unlock the energy in the starches, that energy isn't made available until just about the time the energy from the sugars is wearing off, which stretches out the time until your brain gets sent the "Time to refuel!" message.
Fats come in two main varieties: Saturated and Unsaturated. Saturated fats are usually stiffer (higher melting point) than their unsaturated counterparts. Unsaturated fats are "better" for you because they have room for loose hydrogen to latch on, thereby keeping it from rampaging through your body, oxidizing as it goes. Hydrogenation is the process by which extra hydrogen is forced to join with unsaturated fats, usually to raise the melting point (to make it more solid at room temperature) but this also ruins the hydrogen-scavenging benefits those unsaturated fats had in the first place. Also, hydrogenation converts a lot of the fat into trans-fats, which will then shoot your triglyceride levels through the roof (you don't want this).
Proteins can be burned as energy, but really they (or their component amino acids) should be eaten with the idea of building/maintaining the actual structure of your body rather than as an energy source. The US RDA for protein is about 50g/day, but really this is one stat which should be adjusted based on your body weight. If you are doing strength training then you are going to want to increase your protein intake beyond the maintenance level so that your body has enough to rebuild more than you are destroying. Usually you will be able to tell...if your muscle soreness from workouts gets worse or doesn't subside after a few days, then you probably want to increase your protein intake, split your protein intake up into more snacks per day, or possibly pursue a more bio-available form. Meat (especially fish) is a great source of protein, but it is not the only source. Legumes, nuts, whole grains (including the germ), brewer's yeast, eggs, and dairy (cheese, whey, etc) are all great non-meat sources. You'll be a lot better off mixing up your sources rather than depending on any single source of protein. Actually, you should mix up all your food categories. You don't ever want to lock yourself into any single fruit, vegetable, nut, or whatever. Keep your system on its toes. Rotating your sources will also help you minimize exposure to things that would pile up if you went mono-source (such as mercury in fish, pesticides with legumes, or antibiotics/hormones in dairy/beef, etc).
Needless to say, the quality of the food you eat will have a huge bearing on how good it really is for you. Meat from a grass-fed cow which led an active life free of hormones will be much better for you than that from a grain-fed cow which led a stress-filled life full of antibiotics. The difference with Omega fatty acids is staggering. The same is true of produce (vine-ripened v. boxcar-ripened, etc) but it's especially important with meats since all the stuff that applies to produce also applies to meats since it determined the quality of the feed that went into those meats. We won't even get into the GMO issue until more testing has been done and more results are in.
Switching your diet over to nutrient-dense food should have the benefit of satisfying your nutritional needs with less intake of food, but in case your body rebels at how much emptier your stomach is, remember that you can always make yourself feel fuller by eating foods with lower calorie/high fiber content (green peppers and other produce, fruits such as apples, eating the entire interior of an orange instead of just the juicy bits) or by drinking more water to fill up space (which you should probably be doing anyway) until your stomach gets used to the multiple-feedings-per-day schedule and shrinks in response (which it will, guaranteed). A smaller stomach feels full faster, which reduces the temptation to snack when you don't really need one.
One more thing about eating before you go to bed. From what I've heard/read, it's actually a good idea (assuming you are not afflicted with GERD/bad reflux) to have yourself a little high-carb snack before hitting the sack. Pick something with a high ratio of complex carbs with maybe a little bit of simple sugary garnish (a banana dipped in molasses, a small bowl of cereal/oatmeal with a bit of fruit, or celery with a bit of peanut butter) before you brush your teeth for the evening. The activation of your digestion machinery and the feeling of satisfaction will help you sleep better. The same sort of thing is good for after a meal. Having a bit of sweet at the end of your meal helps tell your body/brain that the meal is over, and gives a cue for closure.
I could go into a lot more food-related topics (vitamin absorption v. mineral absorption, fermented/raw foods, etc) but I believe the above should be plenty informative and be a good start for anyone who hadn't heard all of this before. Now, on to activity.
Simply put, more activity is better. I don't necessarily mean that more intense activity is better, just that more activity is better. You want to convince your body to turn up its thermostat, and you do that by increasing the amount of sustained activity(-ies) you experience throughout the day. Three flights of stairs too much? Just take one set of stairs, but do it slooower. Stuck at your desk? Bounce your leg. Stretch more often. Press your feet together sideways behind the privacy panel. Lift yourself up in your chair by tensing your buttocks and keep it there a minute. Hold your coffee cup at arm's length while you're on hold. Turn your knees 90° to your torso and then go the other way (good for your back). You're going to want to do this kind of stuff to avoid DVT anyway. Starting in the parking lot, hold your briefcase in front of your sternum rather than at your side, and hold it there all the way in. There is absolutely no need to limit your workout only to activities which punish your joints, make you sweat/stink, jangle your organs all over the place, make you ache, or which involve yelling/grunting/screaming. It should be relatively easy to modify your daily routine to make it harder and get your breathing/heart rates up, but not so much that you break out in a sweat or possibly injure yourself.
Whatever activities you choose for your workout, make sure you include at least one activity which involves sustained use of your upper leg muscles. Biking, running, yoga, power walking, stairs, rowing, something. While you use the large muscles of your legs, the constant tense/relax cycle causes the muscles themselves to squeeze blood through your system, supplementing the action of your heart. If your legs share the load, that means your heart doesn't have to work as hard, which is better for your heart.
Last year, I joined a fitness challenge at my job. The idea was to run and keep track of your progress using the Nike+ app. Well, I hate running, so I decided to walk it, instead. Over the course of about 5-6 weeks, I put in just over 250 miles. Walking. And about 32 miles of that was over the last 2 days because I put some of it off (this resulted in me getting plantar fasciitis, which is only now starting to go away. Moral of the story...get good shoes before your feet start hurting). While I was doing this, I noticed something. Whenever I went out walking, from a fitness standpoint, the first hour might as well have not even existed. Every time I went out, it always took at least 45 minutes before my body basically said, "Waitaminit. You're serious about this, aren't you?" So all I'm saying is that if you are going out for cardio or circuit training, make sure to budget at least an hour's worth of time for it to actually "sink in," and also make sure that your level of exertion is one you are going to be able to sustain for that full hour. Don't push so hard that you run out in 25 minutes, no matter how manly it makes you feel or how many reps you did. Stay toasty warm for 60 minutes rather than hot for 20.
Lastly (it's getting late and I need to go bed), I want to touch on something that gets frequently ignored by the vocal fitness crowd, and that's mental fitness and health. I know I shouldn't need to go into a lengthy explanation about how much harm your brain can do to your body if you aren't happy with yourself. We already have entire threads devoted to serving as examples of this. Time and time again, study after study confirms what really should be obvious, that our mental state directly influences our physical state. I'm sure this brings to mind any number of New Age connotations, but try to remember this distilled bit of wisdom: if all you do is stress about how little you're doing, how many workouts you miss, how little progress you're making, how few pounds you've lost, how tired you are, how much life sucks, how floppy your hooties are, etc, etc, you are actually going to initiate biochemical processes within your body which will make it harder for you to succeed. If, instead, you pay all the minutiae no mind BUT you stick with it dependably (on Faith, so to speak) for at least a month, then at the end of that month...how will you not see progress? I would almost be willing to bet that you could skip all your workouts, not change your diet or other habits at all, and so long as you maintained a genuinely positive outlook on your life and managed to sidestep the stresses, you would probably find you had lost either 5-10 pounds or an inch from someplace unimportant yet noticeable.
Keep us posted. You may yet serve as an inspiration to others, or more of one to some.
--Patrick