Just In Time For Christmas
First of all, shop regularly and systematically in thrift stores and don't let yourself be discouraged that so few Big and Tall clothes show up there. When they do, they will be gems. Be content to find one or two pieces that look good and are in good shape on the good days, and take the bad days as they come. Be persistent and shop the same stores regularly, for you are looking to catch things before anyone else rotund has seen them.
Second, buy your dress shirt collars a little large. Snug fitting here means a very bad set to the collar which gives you a sea-turtle look. It takes a larger collar to lie properly on a thick neck, with the proper knot style in the tie, so you can set the collar to best effect, As a bonus, the larger collar will be more comfortable and your constant discomfort will not ruin your good looks. Avoid collar styles that are too exaggeratedly narrow or too wide.
In addition, wear three-piece dress ensembles, preferably with two button coat styles and longer lapels, though these last are optional. Don't be buffaloed by the fact that you see them on no one else--you will look better in them, for you should wear an open suitcoat for its freedom of movement and its better drape over your heft. If you can't find three-piece suits, buy deep v-neck sweater vests (try the thrift stores here) or button cardigan sweater vests (button all the buttons if you do).
Do not buy sleeved sweaters, buy cotton exclusively, and buy them about a size smaller than normal (XL if your shirts are 2X, ect.). Cotton stretches and will look sloppy in your usual size, and wool or acrylic will be too warm indoors, even with the coat off. Always be willing to shed your coat if you have a good sweater vest and can hang the coat up neatly--uncovered shirt sleeves lengthen your figure. Wear French cuffs with discreet but rich links, if you like. They go well with a jacketless silhouette indoors, but avoid white cuffs and collars on colored shirts.
As a general rule, always remember that you already have an extra layer of insulation and choose your fabrics accordingly. So both knitted cotton sweater vests and tropical weight wool suiting, made for summer wear, will serve you far deeper into the late fall or the early spring than they do for your thinner brethren. I am only a 2x in shirt size at a height of 5' 7", and the mercury has to be near 0F degrees for me to feel at all comfortable in knitted wool winter sweaters.
Wear suspenders underneath the vest and avoid belts. Make the effort to have your cleaners add brace buttons to the trousers. Or, if you can always conceal them with a vest, go to hardware stores (Sears is excellent!) and buy the heavy-duty clip suspenders made for skilled tradesmen. Trousers always drape better with suspenders than they do with belts, and will, again, be more comfortable in the bargain. A further tip: if possible, attach suspender clips exactly over belt loops for a more secure hold.
Write this rule out in large letters and place it on the mirror in which you look while you are dressing: never, never, never, for any reason whatever, expose the belt line of a shirt which is tucked inside your pants. The size of your waist is the biggest thing about you and a horizontal line drawn exactly across your waist makes it look far bigger. Not to mention the fact that, if you are wearing a belt, you are probably slopping over the belt as you walk.
Your vest gives you the freedom to tie Windsor and Half-Windsor knots in your ties and to wear the tip of them a little short. Take advantage of this, because both of these knots will give you better control of the set of your shirt collar than a four-in-hand knot. Wear a concealed tie clip, hooking the rear dangle of the tie to your shirt button placket just above the tie keeping label. This will help prevent natural movement from badly disarranging the set of your tie as it rubs against the resistant textured cotton of your sweater vest. New tie clips are hard to come by, so look for them regularly in thrift stores and yard sales.
Choose your colors and patterns of suiting carefully and eschew exaggerated contrasts of tone, pattern, or hue; avoid chalk stripes, or plain solids, in suits and jackets; and seek out very subtle thread color patternings in all your dress wear. Understated herringbones, tick tweeds, delicate glen plaids, and mixed color weaves are usually excellent. What the Brits call a very slightly "country" look to the suiting will almost always flatter you best.
Also, avoid strong shirt patterns, such as exaggerated stripes or white cuffs and collars on colored shirts. Most tie patterns, even quite bold ones, will suit you, but use this rule of thumb: the more of the tie that you show, the less bold the tie pattern should be. With a good vest and Windsor or Half-Windsor knots you can play the tie up as bold as you like or play it down as much as you need.
Unless you can afford a really expensive version, avoid the current fashion for black or near black suiting. Nothing looks cheaper than a cheap black suit. If you wear black, the dye should be so black that you cannot discern the surface texture of the fabric at any distance further away than that of a standing conversation. This means the most expensive black fabrics and nothing less.
Look for contrasting textural interest between your sweater vests, your shirts, and your suiting. Pair a satiny textured suit with beefy oxford cloth shirting and fine knit sweater fabric. Or a thick knit rope pattern sweater with a smooth and crisp Egyptian cotton broadcloth shirt and a matte textured suit with a subtle glen plaid. You will, of necessity, be displaying a large amount of fabric, so it should look as expensive, substantial, and touch friendly as possible. Think of a lady friend who can't resist running her soft smooth hands down the lapel of your suitcoat and you will have it about right.
Heavier men have a harder time achieving the proper "break" of the trouser cuff over the top of the shoe and the exact one-half inch of shirt cuff showing below the jacket cuff. Wear pleated trousers always, don't be afraid to buy shirt sleeves a little long, and have jacket sleeves and trouser lengths carefully altered, if need be, to achieve this. Also, consider "half-boot" slip-on shoe styles and cuffless trousers for a more forgiving treatment at the ankles, and care for your dress shoes (with regular mink oil and horsehair brushing if they are not suede) religiously.
I have gone into great detail about dress wear for a very specific reason. Once you have a truly comfortable wardrobe of dress clothing, you should always wear it wherever appropriate, even if dress clothing is optional at the particular event.
An important stereotype about those of us who are obese is that we are sloppy and do not take care of our appearance. There can be a certain amount of truth to this. The deck is so stacked against us dressing well that it is very easy to simply get discouraged and lose enough self-esteem that we no longer try to look our best.
You break that stereotype by dressing up, dressing comfortably, and dressing well. You should dress as if you mean it. Do this and you will notice very rapidly that you are far more widely respected than you were before you started doing it.
There are also ways for obese men to dress casually without appearing sloppy or ridiculous. For casual tops that give three season wear choose the following: long sleeved Rugby shirts, short sleeved polo shirts, and cotton fatigue sweaters, all worn outside the beltline.
All of these are usually cut better than average in the bigger sizes, and Rugby shirts, particularly, are designed for big men to both look good and move freely in them. Their patterns are usually flattering and they are also among the easiest styles to find in thrift stores.
Once again, wear suspenders under your tops and over your t-shirts (preferably deep v-neck once again), buy pleated twill pants for maximum comfort, always cover your beltline, and choose discreet patterns and colors which flatter your complexion. A girlfriend or wife's eye, if she dresses smartly, is helpful with this--colors and patterns are harder to choose in sports wear than they are in dress wear. Do not buy any sports wear that binds you in any direction when you move. You may need to be quite choosy to achieve this, but take the time and make the effort.
In the summer, break training and switch to all cotton button fronted shirts with straight hems, bought a little large, and worn untucked, over elastic-waisted trousers. Take this season to indulge a little in brighter patterns or colors in the shirting. Crinkled cotton seersucker, if you can find it, is an excellent texture for these. Remember that you will probably feel the heat more than your thinner peers, so use rayon sparingly, mostly for evening wear when the saturated richness of the colors will show to best advantage. Otherwise, choose thin and breathable all cotton.
Thus the sartorial advice of Joe Claus. Finally, if at all possible, don't buy clothes on your own. Always take someone with you whom you trust to be both discerning and honest. The stigma of "be thin to win" makes good judgment when we shop much harder, as well as giving us far fewer choices.