Some of the coolest women I know are seriously overweight. I say, if you're stuck with it, embrace it. It builds character.
Back to the OP, I can see the small, home based made-to-order dress shop as a possible business opportunity for a person with some good sewing skills. It wouldn't make the owner rich, but would provide an additional income. If it were me, I might work mostly off a few basic tunic and skirt, or tunic and pant patterns, keep swatches of suitable fabrics on hand, and order the yardage as soon as the customer placed an order. If the customer's deposit covers the fabric cost, there is not much risk or overhead for the seamstress. I wouldn't keep stock, except for some sample pieces in different sizes that the customer could try on and from there, we could discuss individual preferences for the customer's order.