It is too bad your wife feels insecure...Mary is right. A "warning" sign is a major lifestyle change, which is what you are doing. There are so many reasons to lose weight. Health is a major one. Let her know appearance isn't the only reason you wanted the weight off. Given your job, I would think being healthier, feeling terrific and being in better shape would make things less stressful for you at work. Explain that to her, too. Does she have a weight problem? That could be the root cause of her attitude if she does.