So this extra bit of flesh makes the bra very uncomfortable, almost painful in some cases! You can see the strain on the hooks and eyes. I don't consider this model "fat" but her bra back is clearly not quite wide enough and it cannot be comfortable for her.
Perhaps she is just a woman with a back a bit wider than her front. In other words, the front of the bra fits just fine, but the back is overly tight.
Perhaps she might find this as a "solution". You can buy these bra extenders almost anywhere (We sell them at Bra-makers Supply) and as I said in my rant " I hate 'em, but I sell 'em".
Why? They push the shoulder straps our too far on the shoulders, and unless you have wide square shoulders, the straps will fall off. Imagine this lady with a bra extender...the poor woman would never keep those straps up!
You need to have some length added to the bra back between the strap attachment points and the cups of the bra as shown here.
I finished off my rant with this paragraph...
" If you can sew, lengthening the back band to add some width without having the straps fall off your shoulders is not a difficult task."
A little while later, a reader commented two times on that post
"...does this mean that you would add extra width outside the straps when sewing? " and
"...does this mean those with narrow shoulders would add extra width outside the bra straps? A diagram would be helpful, please."
It dawned on me that not everyone understood what adjustment I was talking about or how to make that adjustment to the pattern. So here is the alteration without further delay:
The alteration affects the back band piece only. It doesn't matter if your band is a short piece that will attach to the front frame piece, or a longer band that attaches directly to the cup, the alteration is done the same way. Here are two different back pattern pieces - yours may look a little different.
Split the back band vertically, between the top edge of the bra (blue line) and the bottom edge (green line).
It doesn't matter whether you split the pattern piece in two near the front toward the frame (the purple line) or the back strap scoop (the yellow marks the back strap scoop)
Cut the back pattern piece anywhere between the purple and yellow lines, but where it splits is up to you. It really doesn't matter, but the cut line must be at right angles to the DOGS line (Direction Of Greatest Stretch) that should be marked on your pattern piece.
How much width do you need to add? Whatever you think you need for a total increase, you will be adding half of that to the back pattern piece (there will be two backs, a left and a right so you will end up with twice as much as what you are adding to the one pattern piece) If you think you need an extra 1" (25 mm) to make the bra back more comfortable, add 1/2" (12 mm).
On a piece of paper, draw a horizontal line at least that distance apart. At right angles to it, draw a line a few inches long. Exactly the distance you need (1/2" or 12 mm) away from the first vertical line, draw a second vertical line parallel to the the first.
Tape one side of the back to the paper matching the vertical line with the cut you made, and the horizontal line with the DOGS line. Tape the other side of the pattern piece to the other vertical line.
By drawing the lines first and taping the pattern pieces to them, we avoid having the pieces shift as we are trying to line them up by eye.
Have you noticed that when you finish taping the pieces down, the points at A and/or B, are no longer even with each other? Don't worry, we'll fix that in the next step.
Join one side to the other by blending the lines. Start at the strap scoop at A and draw either a straight line or a gentle curve over to B. Draw a gently curved line from C to D. Your goal is to keep the lines as close as possible to the original.
Once the pattern has been altered, you can sew the bra as usual!