I wear my bodybugg to bed, yes, I know it's obsessive and a little crazy, but I burn about as many calories sleeping as I do sitting at this computer all day; it really doesn't matter. It's a matter of calories in and calories out.
Your husband's co-worker is probably eating more frequently. If you wolf down your entire calorie allowance for the day in one sitting (and it's MUCH easier than on may think. Eat a number 1 from McD's and you're pretty darned close) your body is going to store the extra calories as fat. It can only handle so much at a time. This is why people are bewildered as to why they're not losing weight.
So, in my opinion, when it comes to fad diets it's pretty much a way of disguising calorie restriction. You could live on Twinkies while laying in the bed if you wanted to and still lose weight, just as long you don't go over your BMR, which is what your body needs to operate. You also need a caloric deficit to lose weight. You have reduce your calorie in take passed your BMR by 500 to lose a pound, approximately 3500 calories, in one week.
Metabolic disorder (OMG! I have a slow metabolism...no, not really. You're just skinny fat and lost all your muscle mass, which burns calories) is rare. The glycemic index is crucial if you're diabetic, not if you're a garden variety individual who wants to lose weight. Weight loss is also 80% diet and 20% exercise. Also remember men lose weight faster than women. We need extra fat for growing them babies, and your body isn't keen on losing it. Men also have more muscle mass, hence faster weight loss. Muscle is alive and needs energy, fat just lays there taking up space. If you’re a heavy person to begin with your body will lose fat fast as opposed to a person who is close to their goal weight. Would you give away your last dollar?
OK. This is long enough. I can go on and on about this. You are right. It's calories in and calories out. Can it be tweaked, yes, but not by much.