Ooh my 2 cents' time.
Muscle doesn't really weigh more than fat, that's one of those fallacy type things. If you have the same sized amount of muscle and fat side by side, the muscle will weigh more, because 1lb of muscle is smaller than 1lb of fat.
If your husband wants to lose his excess fat and tone up his lean muscle tissue then gym combined with Slimming World would be great. Protein shakes are a bit of a gym-goer's lazy way of gaining weight that they can turn into muscle, and a man who's overweight shouldn't really be drinking them (in my humble opinion).
Some fat burning cardio combined with some toning and a good sensible diet will do your husband wonders, and if when he reaches his target weight, he wishes to go onto protein shakes to help him bulk up and be muscley, then speak to a nutritionist and see what they think and recommend.
But after a workout, nowt so energising as a banana, a cereal bar and a bottle of water. To the people who drink those energy drinks (like Powerade) that claim that they 'replace what you have lost through exercise' - unless you're an Olympic athlete, you don't really need them. Ditto protein shakes, unless you're already lean and fit and need bulk to turn into muscle.